Removal of Bisphenol A and 17β-Estradiol by Single-Walled Carbon Nanotubes in Aqueous Solution: Adsorption and Molecular Modeling

Single-walled carbon nanotubes, both before (SWNTs) and after treatment (t-SWNTs) with acidified ammonium persulfate, were successfully used to adsorb bisphenol A (BPA) and 17??-estradiol (E2) from aqueous systems. The surface characteristics of the SWNTs and t-SWNTs were analyzed by measuring their surface charge and by imaging their morphological properties through transmission electron microscopy. The extent of defects on the SWNT scaffold generated through acid etching was analyzed by Raman spectroscopy. A total of 19.4, 15.4, and 14.3?mg/g of BPA was adsorbed on SWNTs, while a total of 8.0, 6.4, and 5.1?mg/g was adsorbed on t-SWNTs with a 72-h contact time at 280, 295, and 315?K, respectively. A significantly high fraction of E2 (27.2?mg/g) was absorbed by both SWNTs and t-SWNTs, as compared to BPA. The adsorption kinetics was analyzed using a pseudo-second-order model. Sorption experiments showed that t-SWNTs adsorbed less than half as much BPA as SWNTs, but their E2 adsorption was similar. The sorption mechanism was investigated by performing molecular-level calculations. Adsorption energies calculated using density functional theory show preferential sorption of E2 to SWNTs and graphene (?26.2?kcal/mol on SWNT and ?34.1?kcal/mol on graphene) compared to BPA (?17.1?kcal/mol on SWNT and ?22.5?kcal/mol on graphene), which were consistent with the experimental findings. Thus, ab initio calculations can mechanistically explain the adsorption differences of BPA and E2 on SWNTs.     

Effects of temperature changes on the endogenous rhythm of oxygen consumption in the Japanese flounder <Emphasis Type="Italic">paralichthys olivaceus</Emphasis>

ABSTRACT:   The effects of temperature changes on the endogenous rhythm of oxygen consumption in the Japanese flounder Paralichthys olivaceus which were acclimated to 3, 14 or 20°C in advance were investigated. The oxygen consumption rate (OCR) of individuals (total length >28 cm) that were acclimated to 3°C, maintained a relatively low value of 6.9 ± 2.3 mL (mean ± SD) O₂/kg ww (wet weight)/h till 5.8°C, which is considered a 'minimum' rate. Thereafter, the OCR gradually increased up to 18.7 mL O₂/kg ww/h at the temperature of 10.6°C. The OCR of individuals acclimated to 14°C stabilized with 124.2 ± 24.1 mL O₂/kg ww/h, when tested at the relatively constant temperature of 14.4 ± 0.17°C. Maximum entropy spectral analysis revealed that the peak OCR occurred at 23.9 h intervals, which could be a circadian rhythm. The mean OCR showed a peak at 06.00–08.00 hours. For the temperature above 25°C in which the fish were acclimated to 20°C, the rhythmic patterns of OCR were observed until the experimental temperature reached 26.4°C. For the temperature above 28.4°C, the metabolic activity rhythm of the OCR was dampened and then the OCR abruptly rose again. It is assumed that the oscillator of the endogenous rhythm lost the governing of normal metabolic activity in Japanese flounders above 28.4°C. These results suggest that the temperatures of around 5.8, 26.4 and 28.4°C are the 'lower limit temperature', 'upper incipient lethal temperature', and the 'critical thermal maximum', respectively, for the endogenous rhythm of oxygen consumption in the Japanese flounder.     

Topical application of epidermal growth factor accelerates wound healing by myofibroblast proliferation and collagen synthesis in rat

Recombinant human epidermal growth factor (rhEGF) stimulates the proliferation and migration of epithelial cells in human cell culture systems and animal models of partial-thickness skin wounds. This study investigated the effect of a topical rhEGF ointment on the rate of wound healing and skin re-epithelialization in a rat full thickness wound model, and verified whether or not the rhEGF treatment affected both myofibroblast proliferation and collagen synthesis in the dermis. When rhEGF (10 µg/g ointment) was applied topically twice a day for 14 days, there was significantly enhanced wound closure from the 5th to the 12th day compared with the control (ointment base treatment) group. A histological examination at the postoperative 7th day revealed that the rhEGF treatment increased the number of proliferating nuclear antigen immunoreactive cells in the epidermis layer. In addition, the immunoreactive area of alpha-smooth muscle actin and the expression of prolyl 4-hydroxylase were significantly higher than those of the control group. Overall, a topical treatment of rhEGF ointment promotes wound healing by increasing the rate of epidermal proliferation and accelerating the level of wound contraction related to myofibroblast proliferation and collagen deposition.