MicroRNAs (miRNAs) play critical roles in many biological processes and are vital biomarkers for disease diagnostics. Hence, it is of significance to develop miRNA biosensors with fast responses, ...high sensitivity, and excellent reliability in living cells. As one kind of DNA molecular machine, DNA amplifiers are very promising for intracellular miRNA imaging due to their nonenzymatic, isothermal working principle and excellent signal-amplification ability. However, the practical application of current DNA amplifiers is still an issue because of their slow kinetics, unsatisfactory efficiency, and false-positive signals. Herein, taking advantage of the spatial-confinement effect on a three-dimensional (3D) finite DNA nanostructure, a FRET-based localized hairpin-DNA cascade amplifier (termed as localized-HDCA) is developed for the rapid, efficient, and reliable imaging of intracellular tumor-related miRNA. The localized-HDCA system consists of two metastable hairpin DNAs (H1 and H2) localized on a DNA nanocube. Benefiting from the spatial-confinement effect in the confined space of DNA nanocubes, not only was the speed of the miRNA-triggered HDCA reaction significantly accelerated (7 times faster), but also the reaction efficiency was greatly improved (2.6 times higher). In addition, the FRET-based 3D finite DNA nanocubes provide this localized-HDCA with improved cell permeability and better nuclease resistance as well as the ability to avoid false-positive signals, which guarantee reliable miRNA imaging in living cells. With these advantages, this strategy is expected to be widely applied to the development of more efficient and robust DNA molecular machines for biomedical research and clinical diagnosis.
Object detection and recognition is widely used in various fields and have become key technologies in computer vision. The distribution of objects in natural images can be roughly divided into ...densely stacked objects and scattered objects. Due to the incomplete attributes or features of some objects in densely stacked distributions, some object detectors have missed local area details or low detection accuracy. In this paper, we propose Cross-splitNet, a novel cross-split method for dense object detection and recognition based on candidate box generation. First, an adaptive feature extraction network is constructed. Different datasets are input into convolutional neural networks with various depths, the generalization of the model. Then, the proposed cross-split algorithm is introduced to guide the different deep networks to learn features of images with various densities, according to intermediate object density classification results. Finally, we adopt a feature pyramid network (FPN) subnet to perform multi-scale feature extraction while retaining lower-layer object information and physical characteristics. The model was trained on the COCO 17, VOC 12, and VOC 07 datasets, which contain a large number of object categories. Our network was compared with several two-stage detectors, and the results show that our model achieved an average precision (AP) of 0.819 at 22.9 frames per second (FPS) on the VOC 07+12 dataset. The mean average precision (mAP) of the object detection model with R50+R2-101 backbones on the COCO dataset was increased by 1.9%.
Under the catalysis of Rh2(OAc)4 (10 mol%) and (±)‐Me‐Pybox (20 mol%) in 1,2‐DCE at 80 °C, the homocoupling/4+1 cycloaddition cascade of diazobarbiturates with diazopyrazolones proceeded readily and ...provided spirobarbiturates in 32–88% chemical yields. The chemical structure of the obtained spirobarbiturates was identified by X‐ray diffraction analysis.
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•Deterministic modeling of cationic ROP of ε-CL based on the method of moment.•Revealing the effect of transesterification reaction on molar mass averages of PCL.•Applying the ...developed model to metal free ROP system catalyzed by TrBF4.•Playing with process conditions to increase the industrial sustainability of PCL synthesis.
Ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) is an efficient way to produce a widely used biodegradable polymer, i.e., poly(ε-caprolactone) (PCL). Compared to coordination ROP, ionic ROP receives great attentions in recent years due to mild reaction conditions and well-defined polymer microstructure. To fully exploit the potential of ionic ROP, in this work, a mathematical kinetic model for activated monomer mechanism (AMM) based cationic ROP of ε-CL was developed based on method of moments (MoM). Using the developed model, we estimated the values of the kinetic coefficients of monomer activation and monomeric units’ protonation reactions. The simulated results are found to be in good agreement with experimental data, as well as the benchmark by kinetic equation. Moreover, the simulations reveal the crucial role of transesterification reaction in molar mass distribution broadening and how the concentrations of acid and alcohol affect the monomer conversion and average molar masses of the polymer. Finally, the model was successfully extended to a newly reported system using trityl tetrafluoroborate (TrBF4) as catalyst, proving the universality of our model. This study provides deeper understanding of the cationic ROP and allows to optimize process conditions to increase the industrial sustainability of PCL-based materials.
The residues from the widely used broad-spectrum environmental herbicide, atrazine (ATR), result in the exposure of nontarget organisms and persist as a global major public health hazard. ATR is ...neurotoxic and may cause adverse health effects in mammals, birds, and fishes. Nevertheless, the molecular mechanism of ATR induced neurotoxicity remains unclear. To assess the molecular mechanisms of ATR-induced cerebral toxicity through potential oxidative damage, quail were treated with ATR by oral gavage administration at doses of 0, 50, 250, and 500 mg/kg body weight daily for 45 days. Markedly, increases in the amount of swelling of neuronal cells, the percentage of mean damaged mitochondria, mitochondrial malformation, and mitochondrial vacuolar degeneration as well as decreases in the mitochondrial cristae and mitochondrial volume density were observed by light and electron microscopy in the cerebrum of quail. ATR induced toxicities in the expression of mitochondrial function-related genes and promoted oxidative damage, as indicated by effects on oxidative stress indices. These results indicated that ATR exposure can cause neurological disorders and cerebral injury. ATR may initiate apoptosis by activating Bcl-2, Bax, and Caspase3 protein expression but failed to induce autophagy (LC3B has not cleaved to LC3BI/II). Furthermore, ATR induced CYP-related enzymes metabolism disorders by activating the nuclear xenobiotic receptors response (NXRs including AHR, CAR, and PXR) and increased expression of several CYP isoforms (including CYP1B1 and CYP2C18) and thereby producing mitochondrial dysfunction. In this study, we observed ATR exposure resulted in oxidative stress and mitochondrial dysfunction by activating the NXR response and interfering the CYP450s homeostasis in quail cerebrum that supported the molecular mechanism of ATR induced cerebrum toxicity. In conclusion, these results provided new evidence on molecular mechanism of ATR induced neurotoxicity.
A stereocontrolled electrophilic amination of α-branched N-tert-butanesulfinyl ketimines was developed to construct α-aminoketone derivatives containing less accessible α-tetrasubstituted ...stereocenters. Stereospecific α-deprotonation of ketimines with potassium tert-butoxide gave stereodefined metalloenamine intermediates that could act as nucleophiles to attack azodicarboxylic derivatives, affording α-aminated products in high yields with excellent stereoselectivities.
EC₅₀and EC₉₅(the effective concentrations to cause inhibitions by 50 and 95%, respectively) are commonly used to express fungicide potency. Different methods are currently employed to calculate ...EC₅₀and EC₉₅values. In this study, EC₅₀and EC₉₅values for fungicide epoxiconazole against 34 isolates of Sclerotinia sclerotiorum were calculated with seven different methods. Results showed that for both EC₅₀and EC₉₅calculations, there was no significant difference among three statistical programs IBM spss®, GraphPad Prism®and dps®(P ≥ 0.066). Methods linear log (linear regression of mycelial growth inhibition vs. logarithmic concentration) and interpolation log (linear interpolation from inhibition and logarithmic concentration data) were not significantly different (P ≥ 0.058) from IBM spss in EC₅₀calculations. These results indicate that among the seven methods, the three statistical programs IBM spss, GraphPad Prism, dps and linear log method are appropriate for EC₅₀calculations. But for EC₉₅calculations, only the three statistical programs are recommended, and GraphPad Prism is likely to give a little higher values than spss and dps.
When a black hole is enclosed in a cavity in asymptotically flat space, an effective volume can be introduced, and an effective pressure can be further defined as its conjugate variable. By this ...means, an extended phase space is constructed in a cavity, which resembles that in the anti‐de Sitter (AdS) space in many aspects. However, there are still some notable dissimilarities simultaneously. In this work, the Joule–Thomson (JT) effect of the black holes, widely discussed in the AdS space as an isenthalpic (constant‐mass) process, is shown to only have cooling region in a cavity. On the contrary, in a constant‐thermal‐energy process (the JT‐like effect), there is only heating region in a cavity. Altogether, different from the AdS case, there is no inversion temperature or inversion curve in a cavity. Our work reveals the subtle discrepancy between the two different extended phase spaces that is sensitive to the specific boundary conditions.
When a black hole is enclosed in a cavity in asymptotically flat space, an effective volume can be introduced, and an effective pressure can be further defined as its conjugate variable. By this means, an extended phase space is constructed in a cavity, which resembles that in the anti‐de Sitter (AdS) space in many aspects. However, there are still some notable dissimilarities simultaneously. In this work, the Joule–Thomson (JT) effect of the black holes, widely discussed in the AdS space as an isenthalpic (constant‐mass) process, is shown to only have cooling region in a cavity. On the contrary, in a constant‐thermal‐energy process (the JT‐like effect), there is only heating region in a cavity. Altogether, different from the AdS case, there is no inversion temperature or inversion curve in a cavity. The work presented here reveals the subtle discrepancy between the two different extended phase spaces that is sensitive to the specific boundary conditions.
•Structural characterization of two polysaccharides from Dendrobium officinale were described.•DOP performed the hypoglycemic activity via stimulating GLP-1 secretion in STZ-induced diabetic rats and ...STC-1 cells.•Ca2+/CaM/CaMKII and MAPK pathways might involve in the intracellular DOP-induced GLP-1 secretion.•The repeated unit of backbone of DOP-1 and DOP-2 might be the effective unit of DOP-induced GLP-1 secretion.
Two polysaccharides, named DOP-1 and DOP-2, with molecular weights of 6.8 kDa and 14.3 kDa, respectively, were isolated and purified from the stems of Dendrobium officinale. Monosaccharide composition, Fourier-transform infrared spectroscopy, methylation, and nuclear magnetic resonance analyses indicated that DOP-1 and DOP-2 may have a backbone consisted of →4)-β-d-Glcp-(1→, →4)-β-d-Manp-(1→, →4)-2-O-acetyl-β-d-Manp-(1→ and →4)-3-O-acetyl-β-d-Manp-(1→. In vivo assays showed that D. officinale polysaccharides (DOPs) exerted significant hypoglycemic effects accompanying increased serum insulin and glucagon-like peptide-1 (GLP-1) levels in streptozotocin-induced diabetic rats. Further in vitro experiments showed that DOP-induced GLP-1 secretion was inhibited by an intracellular calcium chelator, a Ca2+/calmodulin-dependent protein kinase (CaMK) II inhibitor, a specific calcium-sensing receptor antagonist, and a p38-mitogen-activated protein kinases (MAPK) inhibitor. These results indicated that DOPs may decrease fasting blood sugar levels by stimulating GLP-1 secretion and that intracellular DOP-induced GLP-1 secretion involved the Ca2+/calmodulin/CaMKII and MAPK pathways.
The effect of dislocation-RE atoms interactions on the creep behaviour has been studied via creep testing and HAADF-STEM analysis of two extruded alloys; Mg-0.5Ce and Mg-2Gd (wt%). Almost no Ce atoms ...are detected in the Mg matrix due to the low solid solubility and faster diffusion rate in as-extruded condition. However, Gd solute segregations are observed along dislocations and hexagonal dislocation patterns. Such segregations can not only pin the dislocation motion and enhance the creep strengthening via dislocation patterns, but also lead to dynamic precipitation. Thus, combing with the stress exponent values, the transition of creep mechanism between Mg-0.5Ce alloys and Mg-2Gd alloys has been found and dislocation-Gd atoms interactions are determined to be the main factor for superior creep resistance of Mg-2Gd alloys.
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