A single-species population model with migrations and harvest between the protected patch and the unprotected patch is formulated and investigated in this paper. We study the local stability and the global stability of the equilibria. The research points out, under some suitable conditions, the singlespecies population model admits a unique positive equilibrium, which is globally asymptotically stable. We also derive that the trivial solution is globally asymptotically stable when the harvesting rate exceeds the threshold. Further,we discuss the practical effects of the protection zones and the harvest. The main results indicate that the protective zones indeed eliminate the extinction of the species under some cases, and the theoretical threshold of harvest to the practical management of the endangered species is provided as well. To end this contribution and to check the validity of the main results, numerical simulations are separately carried out to illustrate these results. 相似文献
An amperometric aptasensor is reported for the electrochemical determination of the epithelial cell adhesion molecule (EpCAM). It is based on a combination of EpCAM-driven toehold-mediated DNA recycling amplification, the specific recognition of EpCAM aptamer, and its binding to EpCAM. Hairpin probe 1 (Hp1) with a toehold region was modified with a 5′-thiol group (5’-SH) and self-assembled onto the surface of a gold electrode. Upon addition of EpCAM, the probe A (a 15-mer) is liberated from the aptamer/probe A complex and then hybridizes with the toehold domain of Hp1. This results in the exposure of another toehold for further hybridizing with hairpin probe 2 (Hp2) to displace probe A in the presence of Hp2 that was labeled with the electrochemical probe Methylene Blue (MB). Subsequently, liberated probe A is hybridized again with another Hp1 to start the next round of DNA recycling amplification by reusing probe A. This leads to the formation of plenty of MB-labeled DNA strands on the electrode surface and generates an amplified current. This 1:N probe-response amplification results in ultrasensitive and specific detection of EpCAM, with a 20 pg·mL?1 detection limit. The electrode is highly stable and regenerable. It was successfully applied to the determination of EpCAM in spiked human serum, urine and saliva, and thus provides a promising tool for early clinical diagnosis.
Four new compounds, [Me4N]4H5[(RGe)3(XW9O34−n)2] (R = HOOCCH2CH2, HOOCCH2(m-NO2C6H4)CH, X = P, n = 0; X = Sb, n = 1) have been prepared from trichlorogermanium precursors and lacunary polyoxometallates ([PW9O34]9− and [SbW9O33]9−). The products were characterized by means of elemental analysis, IR spectroscopy, 1H NMR and 183W NMR spectroscopy. 183W NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the XW9 units in water. The organogermanium substituted complexes showed promising activity against two human tumor cell lines (leucocythemia Hela cells and S180 cells) in vitro and [Me4N]4H5[(HOOCCH2CH2Ge)3(SbW9O33)2] exhibited some certain antitumoral activity in vivo and can increase the immune ability of the spleen. 相似文献
Preeclampsia (PE) is a complex and serious condition of pregnancy. Trophoblasts in human placenta can be separated and collected by laser capture micro-dissection (LCM). Protein in trophoblasts have been extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), finally 962 unique proteins are identified by liquid chromatography coupled to mass spectrometry (LC-MS/MS). Comparison of differential expressed proteins in normal and those in PE are investigated. Two-dimensional electrophoresis (2DE) and MS were used to identify differential expressed proteins. 13 differential expressed proteins include signal transduction protein, molecular chaperone, cell skeleton proteins are identified, in which 3 proteins are down-regulated and 10 proteins are up-regulated. They might be correlated with the cause of PE. 相似文献
Here, three Schiff bases 3a-c, differing by the substitutions (–H, –Cl, and –N(CH3)2) on the phenyl ring, have been designed and synthesized via the reaction of ortho-aminophenol with benzaldehyde, 2,4-dichlorobenzaldehyde and para-dimethylamine benzaldehyde in 1:1 molar ratio with favourable yields of 89–92%, respectively. Their structural characterizations were studied by FT-IR, NMR, MALDI-MS and elemental analysis. The fluorescence behaviours of compounds 3a and 3b exhibited a severe aggregation caused quenching (ACQ) effect in EtOH/water system. On the contrary, compound 3c had an obvious J-aggregation induced emission (AIE) feature in EtOH/water mixture (v/v?=?1:1), and exhibited excellent sensitivity and anti-interference towards Cu2+ with the limit of detection (LOD) of 1.35?×?10–8 M. Job’s plot analysis and MS spectroscopic study revealed the 2:1 complexation of probe 3c and Cu2+. In addition, probe 3c was successfully applied to the determination of Cu2+ in real aqueous samples.