Loading two organic acids of known molecular structures onto a black carbon was conducted to study the influence of pH and dissolved organic matter on the adsorption of pesticides. Tannic acid at the loading rates of 100 and 300 micromol/g reduced the surface area of black carbon by 18 and 63%, respectively. This was due principally to the blockage of micropores, as verified by measured pore volumes and pore-size distributions. With a comparatively much smaller molecular structure, gallic acid did not apparently influence these properties. The intrinsic acidities of the two acids increased the surface acidity from 1.88 mmol/g of black carbon to 1.93-2.02 mmol/g after DOM loading, resulting in a reduction in isoelectric point pH from 1.93 to 1.66-1.82. The adsorption of propanil, 2,4-D and prometon by black carbon free and loaded of DOM was dependent on pH because major adsorptive forces were the interactions between neutral pesticide molecules and uncharged carbon surfaces. The adsorption was diminished considerably by the deprotonation of 2,4-D and protonation of prometon, as well as the surface charge change of black carbon. Tannic acid of 100 and 300 micromol/g on black carbon reduced the pesticide adsorption at the equilibrium concentration of 10 mg/L by an average of 46 and 81%, respectively, consistent with the reductions of 42 and 81% in micropore volume. At the equilibrium concentration of 30 mg/L, the mesopore surface became the additional adsorptive domain for propanil. Loading tannic acid made the mesopore surface less accessible, due presumably to the enhanced obstruction by tannic acid.

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Abstract. Hepatocellular carcinoma (HCC) remains one of the most common types of malignancy with high mortality and morbidity rates. Previous studies have suggested that microRNAs (miRs) serve pivotal functions in various types of tumor. The aim of the present study was to assess the association between miR-34a expression and HCC cell migration and invasion, and the potential underlying mechanisms. The miR-34a overexpression vector or scramble control was transfected into human Hep3B and Huh7 cell lines. Transwell assays, and Matrigel and wound healing assays were used to detect the effects of miR-34a expression on HCC cell invasion and migration, respectively. The expression of miR-34a and the mRNA expression of other associated proteins were detected using quantitative reverse transcription polymerase chain reaction, and protein levels were measured using western blot analysis. Compared with the control, miR-34a expression was significantly downregulated in Hep3B and Huh7 cells, but this was reversed by the transfection with exogenous miR-34a (P<0.01). The number of migrated or invaded cells was significantly reduced by the overexpression of miR-34a in Hep3B or Huh7 cells (P<0.01). The expression of sirtuin 1 was upregulated, while the level of acetylate-p53 was downregulated by overexpression of miR-34a. Taken together, the results of the present study suggested that the overexpression of miR-34a may have suppressed HCC metastasis via inhibited cell migration and invasion.

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