The authors describe a zinc(II) benzenetricarboxylate (Zn-BTC) based metal-organic framework (MOF) with chrysanthemum-like structure, and its application to the adsorption of pesticides from real water samples. The Zn-BTC MOF was characterized by XRD, TGA, SEM, nitrogen adsorption-desorption analysis and FT-IR spectroscopy. The MOF was used in dispersive solid-phase extraction of six aromatic pesticides from various wastewater samples prior to their quantification by HPLC. Extraction times, extraction temperature, amount of adsorbent, and oscillation rate were optimized. Under the optimal conditions, the method has relative standard deviations (RSDs) of 6.1–10.1%, and good linearity (correlation coefficients higher than 0.9974). The LODs and LOQs for seven pesticides are found to be 0.20–1.60 μg·L?1 and 0.66–5.28 μg·L?1, respectively. The RSDs of within batch extraction are 1.6–9.5% and 3.9–12%.
Graphical abstract Schematic of a zinc-benzenetricarboxylate (Zn-BTC) based metal-organic framework (MOF) for use as an adsorbent of dispersive solid phase extraction (DSPE) of pesticides prior to their determination by HPLC.
One step synthesis of the natural product indirubin by reductive coupling of isatin with KBH4 is described and a possible mechanism for the reaction is proposed. Eleven indirubin derivatives were obtained easily from the corresponding substituted isatin. 相似文献
Acid-mediated domino reaction of ortho-carbonylated alkynyl-substituted arylaldehydes with phenols is described. The implement of this reaction can provide directly a variety of tetracyclic indeno[2,1-c]chromen-7-one products in good yields. The mechanism was proposed to be a domino indanone ring formation/ortho-alkylation of phenols/dehydrated cyclization for the formation of polycyclic skeleton. In addition, several interesting dimeric products containing a pentacyclic scaffold were also afforded stereoselectively albeit in moderate yields. The present transformations feature the use of simple acid catalyst, short reaction time and good substrate scope. 相似文献
Mechanical properties of hybrid PMMA composites reinforced with UHMWPE fiber and nano‐titanium dioxide (2, 4, 6, and 8 wt%) was investigated. In this work, the effect of UHMWPE fiber surface treatment on tensile, flexural, and impact properties of PMMA composites was studied. The fiber loadings were varied from 0% to 20%. The addition of UHMWPE fiber had caused a decline in the tensile strength of the PMMA composite. Results revealed that the presence of titanium dioxide on the surface treated UHMWPE fiber has further enhanced the efficiency of stress transfer from the matrix to the fiber thus improved the interfacial adhesion between the UHMWPE fiber and PMMA matrix. 相似文献
In this paper, the wear performance of an ultra‐high molecular weight polyethylene composites filled with wood fiber were studied using a pin‐on‐disc method. The effects of surface treatment of wood fiber and sliding load and on the friction and wear of the wood fiber/UHMWPE composite are reported. The test results showed that the sliding load is an important controlling factor; its effect is diminished when the wood fiber is modified. 相似文献
An atmospheric microplasma jet system powered by an commercial transformer is developed for investigating the sterilizing efficiency of Escherichia coli in different conditions. The device can be hand-held and operated in the open air. The effect of carrier gas, gas flow rate, distance and treatment time of inactivation is studied. According to the experiment, plasma jet is able to inactivate all the bacteria on the surface in 20 s when the air flow rate is 5 L/min and the distance is 2.0 cm. Besides, the sterilization efficacy with different carrier gas follows an order as bellow: N2 > air > O2 > Ar. The measurements of malondialdehyde content, protein leakage quantity and Mg content are performed as well. In addition, the SEM after plasma treatment reveals that the integrity of E. coli cells is damaged and intracellular particles are excreted into the extracellular space. With discussions upon the mechanisms of surface sterilization, it is found that during the treatment of microplasma, it is mainly the etching actions of electrons and ions on the bacilli that kill the E. coli. Chemical effects rather than physical ones that are responsible for inactivation. Furthermore, the experiment results suggest that there may be better sterilization effect with gas mixture as carrier gas. 相似文献
A novel class of nematic liquid crystalline organic semiconducting oligomers incorporating N-heterocyclic carbazole moieties has been synthesised using simple and highly efficient reaction pathways. The electroluminescent colour of these novel oligomers can be varied in a controlled manner by molecular design. The values of the ionisation potential and the electron affinity of these electroluminescent oligomers can also be matched by structural design to the Highest Occupied Molecular Orbital (HOMO) energy level of the electron-blocking layer and the Lowest Unoccupied Molecular Orbital (LUMO) energy level of electron-transporting layer in the Organic light emitting diodes to create low charge-injection barriers for electrons and holes, respectively leading to electroluminescence with an efficacy up to 4.1 cd A?1. 相似文献