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Addressing the core challenges of achieving both high efficiency and precision in UAV tracking is crucial due to limitations in computing resources, battery capacity, and maximum load capacity on UAVs. Discriminative correlation filter (DCF)-based trackers excel in efficiency on a single CPU but lag in precision. In contrast, many lightweight deep learning (DL)-based trackers based on model compression strike a better balance between efficiency and precision. However, higher compression rates can hinder performance by diminishing discriminative representations. Given these challenges, our paper aims to enhance feature representations' discriminative abilities through an innovative feature-learning approach. We specifically emphasize leveraging contrasting instances to achieve more distinct representations for effective UAV tracking. Our method eliminates the need for manual annotations and facilitates the creation and deployment of lightweight models. As far as our knowledge goes, we are the pioneers in exploring the possibilities of contrastive learning in UAV tracking applications. Through extensive experimentation across four UAV benchmarks, namely, UAVDT, DTB70, UAV123@10fps and VisDrone2018, We have shown that our DRCI (discriminative representation with contrastive instances) tracker outperforms current state-of-the-art UAV tracking methods, underscoring its potential to effectively tackle the persistent challenges in this field. [ABSTRACT FROM AUTHOR]

To explore the fracture evolution of thermally damaged sandstone during loading, this paper carried out uniaxial compression tests on sandstone specimens after different temperature treatments and collected acoustic emission signals during loading. Based on the experimental results, the dynamic evolution of the rock fracture mode was analyzed, and the nonlinear characterization parameters were calculated. Finally, the influence of temperature on the rock fracture evolution was discussed. The results show that (1) the rock strength gradually increases with increasing treatment temperature from 25 to 400 ℃, and the failure process shows a “sudden” evolution characteristic; when the temperature exceeds 400 ℃, the rock strength gradually deteriorates, and the bearing process shows a “progressive” damage accumulation process. (2) When the temperature is lower than 400 ℃, tensile failure-induced cracks are significantly dominant during the rock failure process, while at treatment temperatures higher than 600 ℃, the proportion of shear cracks increases significantly, and the dominance of shear failure mode gradually appears with increasing temperature. (3) The nonlinear dynamic evolution process of the thermally damaged rock during loading includes the transformation between disorder and order. However, when approaching destruction, the sandstone undergoes a self-organizing evolutionary process from chaos to order, which is independent of temperature, indicating that the appearance of the macrofracture zone is the final indicator of the orderly development of the cracks. The research results can provide guidance for understanding the process of thermal damage to surrounding rock masses and analyzing their stability characteristics in engineering practice. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials- based nanozyme are regarded as promising wide-spectrum antibacterial nanoagents due to large surface area and excellent photophysical properties. However, the antibacterial efficacies are still restricted by their low catalytic activity and weak attachment with bacteria. Herein, we report a 2D copper-cobalt oxide nanozyme with porous surfaces and rich defects. The defect-rich porous 2D nanozyme provides abundant highly active sites and vacancy defects, thus exhibiting high peroxidase-mimicking activity, which further enhanced by NIR irradiation, as well as leading to synergistic antibacterial performance with 99% of inhibition ratio of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and significantly promoting wound healing. This work provides useful insights on developing porous and defective 2D nanozymes as a priority towards enhanced antibacterial therapy. The 2D copper-cobalt oxide nanozyme with porous surfaces and rich defects is developed, exerting high peroxidase-mimicking activity, which further enhanced by NIR irradiation, leading to synergistic antibacterial performance with 99% of inhibition ratio of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and significantly promoting wound healing. [ABSTRACT FROM AUTHOR]

Piezoelectric materials convert mechanical stress to electrical energy and thus are widely used in energy harvesting and wearable devices. However, in the piezoelectric family, there are two pairs of properties that improving one of them will generally compromises the other, which limits their applications. The first pair is piezoelectric strain and voltage constant, and the second is piezoelectric performance and mechanical softness. Here, we report a molecular bond weakening strategy to mitigate these issues in organic-inorganic hybrid piezoelectrics. By introduction of large-size halide elements, the metal-halide bonds can be effectively weakened, leading to a softening effect on bond strength and reduction in polarization switching barrier. The obtained solid solution C6H5N(CH3)3CdBr2Cl0.75I0.25 exhibits excellent piezoelectric constants (d33 = 367 pm/V, g33 = 3595 × 10−3 Vm/N), energy harvesting property (power density is 11 W/m2), and superior mechanical softness (0.8 GPa), promising this hybrid as high-performance soft piezoelectrics. Improving piezoelectric strain and voltage constant generally compromises piezoelectric performance and mechanical softness. Here, the authors report a bond weakening strategy for organic-inorganic hybrid piezoelectrics and mitigated these issues. [ABSTRACT FROM AUTHOR]

A fully conjugated azacorannulene dimer with a large π-surface (76π system) was successfully synthesized from a fully conjugated bifunctional polycyclic aromatic azomethine ylide. This molecule represents an example of diaza[80]fullerene (C78N2) fragment molecule bearing two internal nitrogen atoms. X-ray crystallography analysis shows its boat-shaped structure with two terminal azacorannulenes bent in the same direction. The molecular shape leads to unique selective association with a dumbbell-shaped C60 dimer (C120) over C60 through shape recognition. Owing to its large π-surface and a narrow HOMO–LUMO gap, the azacorannulene dimer exhibits red fluorescence with a quantum yield of up to 31%. The utilization of the fully conjugated bifunctional azomethine ylide is a powerful method for the bottom-up synthesis of large multiazafullerene fragments, providing a step towards the selective total synthesis of multiazafullerenes. Heterofullerenes are an important synthetic target for organic chemists. Here, the authors demonstrate a fully conjugated azacorannulene dimer starting from a bifunctional polycyclic aromatic azomethine ylide, providing a powerful method for the bottom-up synthesis of large multiazafullerene fragments [ABSTRACT FROM AUTHOR]

A novel ionic liquid-based air-assisted dispersive liquid–liquid microextraction combined with high-performance liquid chromatographic method was developed for the simultaneous analysis of oxytetracycline, tetracycline, demeclocycline, metacycline, chlortetracycline and doxycycline in honey. Tetracyclines in samples were extracted with ethyl acetate-[Bmim]PF6 under acidic condition with the assistance of air. The analytes were separated on a C18 column thermostated at 20 °C under gradient condition with a mobile phase consisted of methanol and oxalic acid. Parameters for the extraction (pH, dilution buffer, ionic strength, volumes of ionic liquid and ethyl acetate, assistance techniques and extraction time) were evaluated. The developed method showed good linearities over the range of 10.0–500 μg/L (R2 > 0.999). The enrichment factors were 16.6–41.2. The detection limits and quantification limits were 0.434–0.919 μg/kg and 1.45–3.06 μg/kg, respectively. The recoveries were 89.5–116%. The intra-day and inter-day RSDs were 0.644–6.44% and 2.35–15.9%, respectively. The developed method is sensitive, accurate, rapid, convenient, and is applicable for the determination of six tetracyclines in honey. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the role of blood biomarkers regarding preoperative inflammation and coagulation in predicting the postoperative in-hospital mortality of patients with type A acute aortic dissection (AAD). A total of 206 patients with type A AAD who had received surgical treatment were enrolled in this study. Patients were divided into two groups: the death group (28 patients who died during hospitalization) and the survival group (178 patients). Peripheral blood samples were collected before anesthesia induction. Preoperative levels of D-dimer, fibrinogen (FIB), platelet (PLT), white blood cells (WBC) and neutrophil (NEU) were compared between the two groups. Univariable and multivariable logistic regression analysis were utilized to identify the independent risk factors for postoperative in-hospital deaths of patients with type A AAD. Receiver operating characteristic (ROC) curve were used to analyze the predictive value of these indices in the postoperative in-hospital mortality of the patients. Univariable logistic regression analysis showed that the P values of the five parameters including D-dimer, FIB, PLT, WBC and NEU were all less than 0.1, which may be risk factors for postoperative in-hospital deaths of patients with type A AAD. Further multivariable logistic regression analysis indicated that higher preoperative D-dimer and WBC levels were independent risk factors for postoperative in-hospital mortality of patients with type A AAD. ROC curve analysis indicated that application of combining FIB and PLT could improve accuracy in prediction of postoperative in-hospital mortality in patients with type A AAD. Both preoperative D-dimer and WBC in patients with type A AAD may be used as independent risk factors for the postoperative in-hospital mortality of such patients. The combination of FIB and PLT may improve the accuracy of clinical prognostic assessment. [ABSTRACT FROM AUTHOR]

Tea is one of the most popular drinks worldwide. In the process of tea planting, for controlling pests, a variety of pesticides are usually applied. Therefore, pesticide residues and their metabolites in tea leaves, as well as their adverse effects on tea drinkers' health, are becoming increasingly concerning. The tea-leaf matrix is very complex because it is rich in organic acids, polyphenols, natural pigments, catechins, flavonols, metallic/non-metallic elements, and other unconfirmed substances. Hence, it is a great challenge to conduct multi-residue analysis of pesticides in tea samples. Researchers worldwide have been devoted to the development of multi-residue analytical methods for pesticide detection in tea and have made great progress in recent years. In this review, the recent advances in the multi-residue analysis of pesticides in tea matrices, especially those regarding matrix effects and their elimination, sample preparation and detection techniques, were reviewed in depth, and future research directions were suggested as well. [ABSTRACT FROM AUTHOR]

Endovascular treatment (EVT) has been accepted as the standard of care for patients with acute ischemic stroke. The aim of the present study was to compare clinical outcomes of patients who received EVT within and beyond 6 h from symptom onset to groin puncture without perfusion software in Guangdong district, China. Between March 2017 and May 2018, acute ischemic stroke patients who received EVT from 6 comprehensive stroke centers, were enrolled into the registry study. In this subgroup study, we included all patients who had acute proximal large vessel occlusion in the anterior circulation. The demographic, clinical and neuroimaging data were collected from each center. A total of 192 patients were included in this subgroup study. They were divided into two groups: group A (n = 125), within 6 h; group B (n = 67), 6–24 h from symptom onset to groin puncture. There were no substantial differences between these two groups in terms of 90 days favorable outcome (modified Rankin scale [mRS] ≤ 2, P = 0.051) and mortality (P = 0.083), and the risk of symptomatic intracranial hemorrhage at 24 h (P = 0.425). The NIHSS (median 16, IQR12-20, group A; median 12, IQR8-18, group B; P = 0.009) and ASPECTS (median 10, IQR8-10, group A; median 9, IQR8-10, group B; P = 0.034) at baseline were higher in group A. The anesthesia method (general anesthesia, 21.3%, group A vs. 1.5% group B, P = 0.001) were also statistically different between the two groups. The NIHSS and ASPECTS were higher, and general anesthesia was also more widely used in group A. Clinical outcomes were not significantly different within 6 h versus 6–24 h from symptom onset to groin puncture in this real world study. [ABSTRACT FROM AUTHOR]

In this work, a novel fluorescent method for the detection of dopamine (DA) was developed based on a fluorescent nanocomposite (Pdots@AMP-Cu) with polyphenol oxidase activity. Pdots@AMP-Cu was first prepared by the composite of fluorescent polymer dots and coordination nanostructures of adenosine monophosphate (AMP) and Cu2+. The Pdots@AMP-Cu exhibited obvious red fluorescence emission (668 nm), as well as polyphenol oxidase activity by catalyzing the substrate 2,4-DP and 4-AP, and resulted in obvious changes of the solution color from colorless to red. A novel detection method for DA was then developed based on Pdots@AMP-Cu. It is observed that DA can be oxidized by Pdots@AMP-Cu to form eumelanin, and at the same time, the fluorescence of Pdots@AMP-Cu is efficiently quenched by eumelanin due to electron transfer. A good linear relationship was observed between the fluorescent intensity and DA concentration from 10 to 400 μM, and the limit of detection for DA was 4 μM. Moreover, the proposed method exhibited high selectivity toward common amino acids, ascorbic acid, uric acid, etc. And it could also be utilized for DA sensing in human serum samples with satisfactory recoveries. [ABSTRACT FROM AUTHOR]

Echinoderms are an exceptional group of bilaterians that develop pentameral adult symmetry from a bilaterally symmetric larva. However, the genetic basis in evolution and development of this unique transformation remains to be clarified. Here we report newly sequenced genomes, developmental transcriptomes, and proteomes of diverse echinoderms including the green sea urchin (L. variegatus), a sea cucumber (A. japonicus), and with particular emphasis on a sister group of the earliest-diverged echinoderms, the feather star (A. japonica). We learned that the last common ancestor of echinoderms retained a well-organized Hox cluster reminiscent of the hemichordate, and had gene sets involved in endoskeleton development. Further, unlike in other animal groups, the most conserved developmental stages were not at the body plan establishing phase, and genes normally involved in bilaterality appear to function in pentameric axis development. These results enhance our understanding of the divergence of protostomes and deuterostomes almost 500 Mya. Li et al. investigate the evolution and genetic basis of the adult pentameral body plan in echinoderms using genomic, transcriptomic, and proteomic data. They determine that the last common ancestor of echinoderms contained an organized Hox cluster and endoskeleton genes, and suggest that cooption of bilateral development genes was involved in evolution of the pentameric body plan. [ABSTRACT FROM AUTHOR]

Artificially improving traits of cultivated alfalfa (Medicago sativa L.), one of the most important forage crops, is challenging due to the lack of a reference genome and an efficient genome editing protocol, which mainly result from its autotetraploidy and self-incompatibility. Here, we generate an allele-aware chromosome-level genome assembly for the cultivated alfalfa consisting of 32 allelic chromosomes by integrating high-fidelity single-molecule sequencing and Hi-C data. We further establish an efficient CRISPR/Cas9-based genome editing protocol on the basis of this genome assembly and precisely introduce tetra-allelic mutations into null mutants that display obvious phenotype changes. The mutated alleles and phenotypes of null mutants can be stably inherited in generations in a transgene-free manner by cross pollination, which may help in bypassing the debate about transgenic plants. The presented genome and CRISPR/Cas9-based transgene-free genome editing protocol provide key foundations for accelerating research and molecular breeding of this important forage crop. Alfalfa is an important forage crop, but genetic improvement is challenging due to the lack of a reference genome and an efficient genome editing protocol. Here, the authors report the chromosome-level assembly of the autotetraploid genome and a CRISPR/Cas9-based transgene-free genome editing protocol. [ABSTRACT FROM AUTHOR]

Wild edible mushrooms can accumulate significantly elevated levels of mercury from the surrounding environment, which could be harmful to consumers' health. Speciation analysis of mercury in wild edible mushrooms aids in understanding the human exposure to these toxic compounds. In this study, we developed a high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method for the simultaneous determination of inorganic mercury (Hg(II)), methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg) in wild edible mushrooms. A rapid separation of four target mercury species was achieved within 11 min by a C8 column without utilizing high proportion of organic phase in HPLC. The parameters affecting the extraction efficiency of mercury in samples have been investigated. The proposed method showed good linearity within 0–50 μg/L with the detection and quantification limits of 0.6–4.5 μg/kg (S/N = 3), and 2.0–15 μg/kg (S/N = 10), respectively. This proposed method was successfully applied to the mercury speciation analysis in 7 varieties (95 samples) of wild edible mushrooms. The results indicated that in most mushroom samples, mercury mainly occurred as inorganic mercury. But there were two Tricholoma matsutakes, one contained 0.14 mg/kg of methylmercury, another contained 1.05 mg/kg of phenylmercury, which were higher than the maximum allowable content of total mercury in edible mushrooms in China. [ABSTRACT FROM AUTHOR]

Monitoring and imaging glutathione (GSH) in living systems is an essential tool to determine the key roles of GSH in biological pathways, but most fluorescent sensors can only be used in vitro because of their potential biotoxicity. Here, a peptide-based fluorescent sensor, FP, has been successfully designed and synthesized based on the biocompatibility of the peptide backbone and low toxicity. The design strategy of FP contains a specific spatial structure of the peptide sequence which selectively binds to Cu2+, triggering fluorescence quenching. Interestingly, the fluorescence of FP can be fully restored by GSH, due to the strong binding between Cu2+ and the GSH sulfhydryl groups. Finally, the sensor is highly sensitive and selective for imaging GSH both in vitro and in vivo with low toxicity. Thus, FP with its strong "on-off-on" fluorescence changes is a powerful way to image GSH both in cells and zebrafish larvae to study the GSH pathway. [ABSTRACT FROM AUTHOR]

A novel carboxyl Fe3O4 magnetic nanoparticle-based solid-phase extraction combined with high-performance liquid chromatography was developed for the analysis of oxytetracycline, tetracycline, demeclocycline, metacycline, chlortetracycline, and doxycycline in water samples. Driven by the electrostatic interaction and the strong chelation between tetracyclines and iron ions, tetracyclines in samples were adsorbed onto the adsorbents. The adsorbed analytes were subsequently eluted with oxalic acid and separated with a C18 column under gradient condition with a mobile phase consisting of methanol, acetonitrile, and oxalic acid at a flow rate of 0.5 mL/min. The detection was performed at variable ultraviolet wavelengths. Under optimized conditions, the developed method gave an enrichment factor of 33.3, linearity ranges of 5.00-1000 μg/L, detection limits of (2.86-5.19) × 10-2 μg/L, quantification limits of (9.54-17.3) × 10-2 μg/L, recoveries of 76.2-98.0%, and intra- and inter-day RSDs of 0.132-15.5% and 2.28-14.5% for these tetracyclines. The established method was successfully applied for the determination of these six tetracyclines in tap water, river water, pond water, and lake water samples.ᅟ [ABSTRACT FROM AUTHOR]

Based on a novel signal amplification strategy by catalytic hairpin assembly and displacement of G-quadruplex DNA, an enzyme-free, non-label fluorescent aptasensing approach was established for sensitive detection of four tetracycline veterinary drugs in milk. The network consisted of a pair of partially complementary DNA hairpins (HP1 and HP2). The DNA aptamer of four tetracycline veterinary drugs was located at the sticky end of the HP1. The ring region of HP1 rich in G and C could form a stable G-quadruplex structure, which could emit specific fluorescence signal after binding with the fluorescent dye and N-methylmesoporphyrin IX (NMM). When presented in the system, the target analytes would be repeatedly used to trigger a recycling procedure between the hairpins, generating numerous HP1-HP2 duplex complexes and displacing G-quadruplex DNA. Thus, the sensitive detection of target analytes was achieved in a wide linear range (0-1000 μg/L) with the detection limit of 4.6 μg/L. Moreover, this proposed method showed high discrimination efficiency towards target analytes against other common mismatched veterinary drugs, and could be successfully applied to the analysis of milk samples.Schematic of target analyte detection based on catalytic hairpin assembly reaction and displacement of G-quadruplex [ABSTRACT FROM AUTHOR]

A fluorescence turn-on assay for alkaline phosphatase (ALP) activity is developed through the controlled release of polyethyleneimine-capped copper nanoclusters (PEI-capped CuNCs) from the MnO nanosheets. In an aqueous solution, the positively charged PEI-capped CuNCs could be adsorbed onto the surface of the negatively charged MnO nanosheets. Such adsorption through favorable electrostatic interactions could efficiently quench the nanocluster fluorescence emission via resonance energy transfer from the PEI-capped CuNCs to the MnO nanosheets. 2-Phospho- l-ascorbic acid (AAP) could be hydrolyzed to l-ascorbic acid (AA) in the presence of ALP. AA could reduce MnO into Mn and trigger the disintegration of the MnO nanosheets. As a result, the CuNCs were released and the quenched fluorescence was recovered efficiently. The detection strategy is simple, inexpensive, sensitive, selective, with low toxicity, and has better biocompatibility. The newly fabricated biosensor for ALP activity will potentially make it a robust candidate for numerous biological and biomedical applications. [ABSTRACT FROM AUTHOR]

A label-free fluorescence turn-on strategy for alkaline phosphatase (ALP) detection was established based on its enzymatic catalyzed hydrolysis of polyphosphoric acid (PPA, an anionic polymer) that had been utilized for aggregation with our homemade positively charged perylene derivative (Probe-1) via noncovalent interactions. The disaggregation caused turn-on fluorescence signal which was recovered by the released Proble-1 molecules whose original strong fluorescence in an aqueous buffer solution had been quenched due to their previous aggregation induced by PPA. Such method presents its great advantages of free labeling, convenience and simplicity, cost effectiveness, high selectivity, and high sensitivity, with a detection limit of 0.5 mU/mL of ALP. [ABSTRACT FROM AUTHOR]

[25] Liu, J. & Feng, X. Bottom-up synthesis of nitrogen-doped polycyclic aromatic hydrocarbons. In this article references 14, 17, 25 and 32 were incorrect and should have been: [14] Chen, Z., Reuther, U., Hirsch, A. & Thiel, W. Theoretical studies on the substitution patterns in heterofullerenes C SB 70-x sb N SB x sb and C SB 70-x sb B SB x sb (x = 2-10). [Extracted from the article]

The manganese-tetrasulfonatophthalocyanine (MnTSPc) catalyzed luminol–hydrogen peroxide chemiluminescence (CL) systems can be quenched in the presence of proteins. A highly sensitive CL quenching method has been developed for the determination of proteins. Under optimum conditions, the linear ranges of the calibration curves were 0.1–20 µg/mL for human serum albumin (HSA), 0.2–20 µg/mL for human γ-IgG, and 0.5–50 µg/mL for the bovine serum albumin (BSA) with the corresponding detection limits were 1.9 ng/mL, 2.7 ng/mL, and 3.4 ng/mL. The method has been applied to the analysis of total proteins in human serum samples and the results were in good agreement with clinical data provided. [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: https://doi.org/10.1038/s42003-021-02005-4 [ABSTRACT FROM AUTHOR]