Uniform chitosan fibers (CS/PEO) with diameter of 398±76 nm were prepared by electrospinning with merely 5 wt.% of poly(ethylene oxide) (PEO) loading, and then annealed at elevated temperature without the use of additional crosslinker to improve the thermostability and solvent resistance. Swelling test shows that the CS/PEO composite fibers annealed at 200 oC were stable in 50 wt.% acetic acid aqueous solution. The mechanical strength test shows that the annealing temperature can affect the tensile strength of CS/PEO composite fiber mat. The cross-linked CS/PEO composite fibers provide a useful platform for the immobilization of palladium catalyst to catalyze the Mizoroki-Heck reactions of aromatic halides with olefins. Moreover, these CS/PEO composite fibers could be post modified with special ligands to chelate palladium species efficiently to further improve the catalytic activity and stability. 相似文献
The reproductive characteristics of Gymnocypris firmispinatus were determined from 582 individuals collected in the Anning River, China. The sex ratio (male: female) was 1:1 for the overall population but 3.1:1 for the mature group. Females reached a larger total length and total weight (242 mm and 148.17 g) than males (163 mm and 41.58 g). Lengths and ages at maturity were estimated to be 83.4 mm and 2.4 years for males, 130.7 mm and 5.9 years for females, respectively. Based on the analyses of gonad development and the size distribution of oocytes, G. firmispinatus spawned from March to May with high degree of the spawning synchronicity. The opposite tendency between gonado-somatic index and hepato-somatic index from January to March in females indicated that the energy requirement for the oocytes growth may be derived from the liver. In addition, the estimated mean fecundity and mean relative fecundity were 1227 and 29.7 eggs per g total weight. The fecundity of G. firmispinatus increased linearly with increasing of total length, total weight and ovary weight. This study provides details about the reproduction suggesting that G. firmispinatus might be especially vulnerable to exploitation in the Anning River. 相似文献
A lower molecular weight and molar substitution formulation (130/0.4) of hydroxyethyl starch solution has been shown to have a more sustained effect on COP and similar hemodynamic effects as a higher molecular weight and molar substitution formulation (600/0.75) in healthy horses. In humans, these pharmacodynamic characteristics are coupled with more rapid clearance and decreased adverse coagulation effects and accumulation. The objective of this study was to determine and compare the pharmacokinetics of these two formulations in horses. Eight healthy horses were given a 10 mL/kg bolus of each formulation (600/0.75 and 130/0.4) of hydroxyethyl starch solution in a randomized crossover design. Blood was collected, and plasma was harvested for plasma levels over 24 h. Pharmacokinetic parameters for each horse were estimated from a noncompartmental analysis. Treatment with 600/0.75 resulted in a higher initial plasma concentration (C0), systemic half‐life (t1/2), and overall drug exposure (AUC0–inf) in addition to decreased elimination rate (β), volume of distribution (Vd), and clearance (CL), compared to treatment with 130/0.4 (P < 0.001). The pharmacokinetic findings combined with previous pharmacodynamics findings suggest that 130/0.4 can provide similar benefits to 600/0.75 with a lower risk of accumulation in the circulation. 相似文献
Magnetic removal techniques using functionalized magnetic nanoparticles as adsorbents have been frequently tested for use in the removal of heavy metals in aqueous solution, but seldom in farmland soil. Here, a novel magnetic microparticle solid chelator (MSC) was employed as the adsorbent for magnetic removal and/or immobilization of Cd and Zn in a paddy soil (PS), an upland soil (US), and a paddy–upland rotation soil (RS) with different degrees of pollution.
Materials and methods
MSC was applied to 14 kg air-dried soil samples (PS, US, and RS) at the dosage of 1% (w/w), and then watered, and intermittently stirred. Finally, the MSC–metal complexes were retrieved using a magnetic device (MCR treatment) or not (MC treatment), and the removal efficiency of soil Cd and Zn in MCR treatment was evaluated. After magnetic separation of MSC–metal complexes, pot experiments were performed to investigate the impacts of the magnetic remediation process on rice growth, the phytoavailability of soil Cd and Zn, and the accumulation of Cd and Zn in rice plants.
Results and discussion
The MCR treatment exhibited recovery rates of 55.4%, 49.6%, and 19.0% for MSC–metal complexes in PS, US, and RS, respectively, which brought about removal efficiencies of 2.2–12.2% for Cd and 1.9–4.6% for Zn. The MC and MCR treatments substantially decreased the availability of soil Cd, but not soil Zn; this effect was more remarkable when using CaCl2 instead of DTPA as the extractant for determination of bioavailable metals. Furthermore, the CaCl2-extractable Cd and Zn had a more significant relationship with Cd and Zn concentrations in rice roots. The MC and MCR treatments led to dramatic reductions in rice grain Cd of 23.9–72.1% and 37.3–63.9%, respectively, in the three soils relative to the respective controls. The MC and MCR treatments also exhibited an inhibitory effects on rice grain Zn accumulation in US (10.6% and 4.3% decreases, respectively) and RS (9.3% and 19.5% decreases, respectively), but not in PS. Moreover, the grain yield was unaffected under the MCR treatment in the three soils, and significantly increased by 29.8% under the MC treatment in US.
Conclusions
Our study suggests that MSC-based magnetic remediation technique can effectively immobilize and/or remove Cd and Zn in farmland soils, decreasing their uptake by rice plants, with no adverse effects on grain yield.
Non-infectious prenatal mortality severely affects the porcine industry, with pathological placentation as a likely key reason. Previous studies have demonstrated that peroxisome proliferator-activated receptor gamma (PPARγ) deficiency causes defects in the uteroplacental vasculature and induces embryonic losses in mice. However, its role in porcine placental angiogenesis remains unclear. In the present study, PPARγ expression was investigated in porcine uteroplacental tissues at gestational day (GD) 25, GD40 and GD70 via quantitative polymerase chain reaction (qPCR), Western blot and immunohistochemistry (IHC). Moreover, the roles of PPARγ in porcine placental angiogenesis were investigated using a cell model of porcine umbilical vein endothelial cells (PUVECs) to conduct proliferation, migration and tube formation assays in vitro and a mouse xenograft model to assess capillary formation in vivo. The results showed that PPARγ was mainly located in the glandular epithelium, trophoblast, amniotic chorion epithelium and vascular endothelium, as indicated by the higher expression levels at GD25 and GD40 than at GD70 in endometrium and by higher expression levels at GD40 and GD70 than at GD25 in placenta. Moreover, PPARγ expression was significantly downregulated in placenta with dead foetus. In PUVECs, knocking out PPARγ significantly inhibited proliferation, migration and tube formation in vitro and inhibited capillary formation in mouse xenografts in vivo by blocking S-phase, promoting apoptosis and downregulating the angiogenic factors of VEGF and its receptors. Overall, the spatiotemporal heterogeneity of PPARγ expression in porcine uteroplacental tissue suggests its vital role in endometrial remodelling and placental angiogenesis, and PPARγ regulates placental angiogenesis through VEGF-mediated signalling. 相似文献