Spectrum of the doubly heavy tetraquarks, bbq¯q¯, is studied in a constituent quark model. Four-body problem is solved in a variational method where the real scaling technique is used to identify ...resonant states above the fall-apart decay thresholds. In addition to the two bound states that were reported in the previous study we have found several narrow resonant states above the BB⁎ and B⁎B⁎ thresholds. Their structures are studied and are interpreted by the quark dynamics. A narrow resonance with spin-parity JP=1+ is found to be a mixed state of a compact tetraquark and a B⁎B⁎ scattering state. This is driven by a strong color Coulombic attraction between the bb quarks. Negative-parity excited resonances with JP=0−, 1− and 2− form a triplet under the heavy-quark spin symmetry. It turns out that they share a similar structure to the λ-mode of a singly heavy baryon as a result of the strongly attractive correlation for the doubly heavy diquark.
A novel probe was synthesized with a turn-on NIR fluorescent (NIRF)/photoacoustic (PA) response to NADPH, which was successfully applied in both monitoring intracellular NADPH and dual-modal imaging ...of tumor-bearing mice. It exhibits good potential in studying and understanding the tumor energy metabolism and treatment process related to NADPH.
A synthetic DNA machine performs quasi-mechanical movements in response to external intervention, suggesting the promise of constructing sensitive and specific biosensors. Herein, a smart DNA walker ...biosensor for label-free detection of carcinoembryonic antigen (CEA) is developed for the first time by a novel cascade amplification strategy of exonuclease (Exo) III-assisted target recycling amplification (ERA) and DNA walker. ERA as the first stage of amplification generates the walker DNA, while the autonomous traveling of the walker DNA on the substrate-modified silica microspheres as the second stage of amplification produces an ultrasensitive fluorescent signal with the help of N-methylmesoporphyrin IX (NMM). The DNA machine as a biosensor could be applied for transducing and quantifying signals from isothermal molecular amplifications, avoiding the complicated reporter elements and thermal cycling. The present biosensor achieves a detection limit of 1.2 pg·mL–1 within a linear range of 10 pg·mL–1 to 100 ng·mL–1 for CEA, along with a favorable specificity. The practical applicability of the biosensor is demonstrated by the detection of CEA in human serum with satisfactory results; thus, it shows great potential in clinical diagnosis.
Chemical warfare agents (CWAs) are toxic chemicals that have been intentionally developed for targeted and deadly use on humans. Although intended for military targets, the use of CWAs more often ...than not results in mass civilian casualties. To prevent further atrocities from occurring during conflicts, a global ban was implemented through the chemical weapons convention, with the aim of eliminating the development, stockpiling, and use of CWAs. Unfortunately, because of their relatively low cost, ease of manufacture and effectiveness on mass populations, CWAs still exist in today's world. CWAs have been used in several recent terrorist-related incidents and conflicts (
, Syria). Therefore, they continue to remain serious threats to public health and safety and to global peace and stability. Analytical methods that can accurately detect CWAs are essential to global security measures and for forensic analysis. Small molecule fluorescent probes have emerged as attractive chemical tools for CWA detection, due to their simplicity, ease of use, excellent selectivity and high sensitivity, as well as their ability to be translated into handheld devices. This includes the ability to non-invasively image CWA distribution within living systems (
and
) to permit in-depth evaluation of their biological interactions and allow potential identification of therapeutic countermeasures. In this review, we provide an overview of the various reported fluorescent probes that have been designed for the detection of CWAs. The mechanism for CWA detection, change in optical output and application for each fluorescent probe are described in detail. The limitations and challenges of currently developed fluorescent probes are discussed providing insight into the future development of this research area. We hope the information provided in this review will give readers a clear understanding of how to design a fluorescent probe for the detection of a specific CWA. We anticipate that this will advance our security systems and provide new tools for environmental and toxicology monitoring.
Polypropylene (PP), a fossil-based polyolefin plastics widely used worldwide, is non-hydrolyzable and resistant to biodegradation as a major source of plastic pollutants in environment. This study ...focused on feasibility of PP biodegradation in the larvae of two species of darkling beetles (Coleoptera: Tenebrionidae) i.e., yellow mealworms (Tenebrio molitor) and superworms (Zophobas atratus) using PP foam with number-, weight-, and size-average molecular weights (Mn, Mw, and Mz) of 109.8, 356.2, and 765.0 kDa, respectively. The tests were conducted in duplicates with respective larvae (300 T. molitor and 200 Z. atratus each incubator) at 25 °C and 65% humidity for over a 35-day period. The larvae of T. molitor and Z. atratus fed with PP foam as sole diet consumed PP at 1.0 ± 0.4 and 3.1 ± 0.4 mg 100 larvae−1 days−1, respectively; when fed the PP foam plus wheat bran, the consumption rates were enhanced by 68.11% and 39.70%, respectively. Gel permeation chromatography analyses of the frass of T. molitor and Z. atratus larvae fed PP only indicated that Mw was decreased by 20.4 ± 0.8% and 9.0 ± 0.4%; Mn was increased by 12.1 ± 0.4% and 61.5 ± 2.5%; Mz was decreased by 33.8 ± 1.5% and 32.0 ± 1.1%, indicating limited extent depolymerization. Oxidation and biodegradation of PP was confirmed through analysis of the residual PP in frass. Depression of gut microbes with the antibiotic gentamicin inhibited PP depolymerization in both T. molitor and Z. atratus larvae. High throughput 16S rRNA sequencing revealed that Citrobacter sp. and Enterobacter sp. were associated with PP diets in the gut microbiome of Z. atratus larvae while Kluyvera was predominant in the T. molitor larvae. The results indicated that PP can be biodegraded in both T. molitor and Z. atratus larvae via gut microbe-dependent depolymerization with diversified microbiomes.
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•Tenebrio molitor and Zophobas atratus consumed PP foam.•PP was biodegraded via limited extent depolymerization with Mz reduction >32%.•Antibiotic tests indicated gut-microbe dependent biodegradation in both larvae.•Microbiome shifted with distinct dominant species during PP degradation.
•Litter coverage accelerates biocrusts’ decomposition in sandy ecosystems.•Litter-covered biocrusts can further improve topsoil nutrients and microhabitats.•Sandy soil fractal dimension (D) ...significantly increased with litter cover.•Litter cover promotes the transformation of sandy to loamy textures.
Ecological restoration of sandy inland ecosystems is important for achieving global sustainability. In the world’s semi-arid regions, soil crusts play crucial roles in maintaining ecosystem functioning. However, the true extent of soil quality improvement during the development of crusts is an issue not solved. In this study, four development stages of natural soil crusts, i.e., physical crusts (PC), biocrusts (BC), litter covered biocrusts (LBC) and litter crusts (LC) were selected in a semi-arid sandy ecosystem, along with a bare sandy land (BSL) as control area, to evaluate soil physicochemical properties at different soil depths. The coverage of litter (mainly leaves of Populus simonii) increased soil moisture and reduced soil bulk density. Compared with BC, the content of total soil organic matter (SOM) decreased in LBC by 13.83% and increased in LC by 36.57%. In contrast with BC, LC promoted a significant increase in soil nutrients, such as total nitrogen (30.30%), total phosphorus (46.89%) and available potassium (34.40%) in the topsoil layer (0–2 cm). Besides, LC contained higher clay and silt contents (10.47% and 29.81%) and lower sand content (−1.02%) than BC. In the 0–10 cm soil layer, the D (fractal dimension of the soil particle size distribution) of LC was the largest, with a value 5.71%, 6.1%, 2.44% and 0.93% higher than D in BSL, PC, BC and LBC, respectively. These findings reveal that litter covering facilitate the disintegration of BC, which further forms LC, and these processes clearly promote the enhancement of soil quality under sandy semi-arid conditions. Our findings are particularly important for predicting the transformation processes of sandy soil crusts and are of interest in ecological restoration programs.
Aptamers for Ebola virus (EBOV) offer a powerful means for prevention and diagnostics. Unfortunately, few aptamers for EBOV have been discovered yet. Herein, assisted by magnetism-controlled ...selection chips to strictly manipulate selection conditions, a highly efficient aptamer selection platform for EBOV is proposed. With highly stringent selection conditions of rigorous washing, manipulation of minuscule amounts of magnetic beads, and real-time evaluation of the selection effectiveness, the selection performance of the platform was improved significantly. In only three rounds of selection, the high-performance aptamers for EBOV GP and NP proteins were obtained simultaneously, with dissociation constants (K d) in the nanomolar range. The aptamer was further applied to the detection of EBOV successfully, with a detection limit of 4.2 ng/mL. The whole detection process that consisted of sample mixing, separation, and signal acquisition was highly integrated and conducted in a magnetism-controlled detection chip, showing high biosafety and great potential for point-of-care detection. The method may open up new avenues for prevention and control of EBOV.
Simple, rapid, sensitive, and specific detection of cancer cells plays a pivotal role in the diagnosis and prognosis of cancer. A sandwich electrochemical biosensor was developed based on polyadenine ...(polydA)-aptamer modified gold electrode (GE) and polydA-aptamer functionalized gold nanoparticles/graphene oxide (AuNPs/GO) hybrid for the label-free and selective detection of breast cancer cells (MCF-7) via a differential pulse voltammetry (DPV) technique. Due to the intrinsic affinity between multiple consecutive adenines of polydA sequences and gold, polydA modified aptamer instead of thiol terminated aptamer was immobilized on the surface of GE and AuNPs/GO. The label-free MCF-7 cells could be recognized by polydA-aptamer and self-assembled onto the surface of GE. The polydA-aptamer functionalized AuNPs/GO hybrid could further bind to MCF-7 cells to form a sandwich sensing system. Characterization of the surface modified GE was carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using Fe(CN)63-/4- as a redox probe. Under the optimized experimental conditions, a detection limit of 8 cellsmL−1 (3σ/slope) was obtained for MCF-7 cells by the present electrochemical biosensor, along with a linear range of 10–105 cellsmL−1. By virtue of excellent sensitivity, specificity and repeatability, the present electrochemical biosensor provides a potential application in point-of-care cancer diagnosis.
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•A label-free and sandwich electrochemical biosensor was developed for MCF-7 detection.•Aptamer was anchored on the surface of gold electrode by using polyadenine instead of thiol.•The electrochemical biosensor offered high sensitivity and selectivity toward MCF-7 breast cancer cells.
Many resting‐state functional magnetic resonance imaging (rs‐fMRI) studies have explored abnormal regional spontaneous brain activity in migraine. However, these results are inconsistent. To identify ...the consistent regions with abnormal neural activity, we meta‐analyzed these studies. We gathered whole‐brain rs‐fMRI studies measuring differences in the amplitude of low‐frequency fluctuations (ALFF), fractional ALFF (fALFF), or regional homogeneity (ReHo) methods. Then, we performed a voxel‐wise meta‐analysis to identify consistent abnormal neural activity in migraine by anisotropic effect size seed‐based d mapping (AES‐SDM). To confirm the AES‐SDM meta‐analysis results, we conducted two meta‐analyses: activation likelihood estimation (ALE) and multi‐level kernel density analysis (MKDA). We found that migraine showed increased regional neural activities in the bilateral postcentral gyrus (PoCG), left hippocampus (HIP.L), right pons, left superior frontal gyrus (SFG.L), triangular part of right inferior frontal gyrus (IFGtriang.R), right middle frontal gyrus (MFG.R), and left precentral gyrus (PreCG.L) and decreased regional intrinsic brain activities were exhibited in the right angular gyrus (ANG.R), left superior occipital gyrus (SOG.L), right lingual gyrus (LING.R). Moreover, the meta‐analysis of ALE further validated the abnormal neural activities in the PoCG, right pons, ANG.R, and HIP. Meta‐regression demonstrated that headache intensity was positively associated with the abnormal activities in the HIP.L, ANG.R, and LING.R. These findings suggest that migraine is associated with abnormal spontaneous brain activities of some pain‐related regions, which may contribute to a deeper understanding of the neural mechanism of migraine.
Migraine is a common neurologic disorder. We identified consistent regional neural activity alteration in migraine patients using anisotropic effect‐size seed‐based d mapping (AES‐SDM), activation likelihood estimation (ALE), and multi‐level kernel density analysis (MKDA). The findings revealed consistent abnormal brain activities which deepen our understanding of the pathological mechanism of migraine.
Both selenium (Se) and melatonin reduce cadmium (Cd) uptake and mitigate Cd toxicity in plants. However, the relationship between Se and melatonin in Cd detoxification remains unclear. In this study, ...we investigated the influence of three forms of Se (selenocysteine, sodium selenite, and sodium selenate) on the biosynthesis of melatonin and the tolerance against Cd in tomato plants. Pretreatment with different forms of Se significantly induced the biosynthesis of melatonin and its precursors (tryptophan, tryptamine, and serotonin); selenocysteine had the most marked effect on melatonin biosynthesis. Furthermore, Se and melatonin supplements significantly increased plant Cd tolerance as evidenced by decreased growth inhibition, photoinhibition, and electrolyte leakage (EL). Se‐induced Cd tolerance was compromised in melatonin‐deficient plants following tryptophan decarboxylase (TDC) gene silencing. Se treatment increased the levels of glutathione (GSH) and phytochelatins (PCs), as well as the expression of GSH and PC biosynthetic genes in nonsilenced plants, but the effects of Se were compromised in TDC‐silenced plants under Cd stress. In addition, Se and melatonin supplements reduced Cd content in leaves of nonsilenced plants, but Se‐induced reduction in Cd content was compromised in leaves of TDC‐silenced plants. Taken together, our results indicate that melatonin is involved in Se‐induced Cd tolerance via the regulation of Cd detoxification.
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