RESUMO
In this paper, the aluminium-doped carbon dots (Al-CDs) were developed for simultaneous selective detection of five tetracycline antibiotics (TCs), including minocycline (MC), tetracycline (TC), oxytetracycline (OTC), doxycycline (DOC) and chlortetracycline (CTC). With the bright blue fluorescence, Al-CDs displayed excellent stability and showed no obvious fluorescence intensity changes under different ionic strength, acidic or alkaline environment, continuous ultraviolet light illumination, and even longtime storage at room temperature. As adding different antibiotics, the fluorescence of Al-CDs was strongly quenched by five TCs and showed no distinguished changes with the addition of other kinds of antibiotics. The presence of interferential metal ions, anions and small organic molecules imposed no effect on the simultaneous selective detection of five TCs. A good linear relationship was achieved for five TCs in the range of 0-100 µM, and the limit of detection for MC, TC, OTC, DOC, and CTC were 13.91 (0-100 µM), 15.54 (0-100 µM), 14.26 (0-100 µM), 13.48 (0-100 µM) and 13.88 nM (0-100 µM), respectively. Moreover, Al-CDs was successfully used to the detection of five TCs in real samples with recovery ranging from 92.47% to 122.05%, confirming a bright future for the practical applications in the assays of foods, medicines, and environments.
RESUMO
The high adsorption capacity of coal reservoirs poses a challenge to the evaluation of productivity and output profiles for each segment of fractured horizontal wells using tracers. In this study, the microstructure of a coal sample from block B and its absorption character to a micromaterial tracer are analyzed first. Then, an anti-adsorption micromaterial tracer system which is suitable for block B is proposed by evaluating different types of complexing agents and extractant agents. The system comprises micromaterial tracers (200 ppb) + ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na in short) (0.01%) + di(2-ethylhexyl) phosphate (HDEHP in short) (0.001%), and its anti-adsorption character of the system is analyzed. The concentration dynamics of micromaterial tracers are analyzed by the flowback fluid testing of one fracturing well and two adjacent wells. Then, a judging method for productivity and connectivity of each segment of horizontal wells is established. Moreover, the anti-adsorption micromaterial tracer system judgment method is employed to analyze the staged fracturing performance of horizontal well B1 in the coal reservoir of block B. Eight types of micromaterial tracers are utilized to label the fluid in each fracturing segment for assessing the connectivity between well B1 and adjacent wells B1-1 and B1-2. The results show that the anti-adsorption micromaterial tracer system exhibits minimal adsorption loss and can be well applied in segment monitoring in the horizontal fracturing well of coal reservoirs. The main productive segments of well B1 are #1, #4, and #8. Well B1 exhibits good connectivity with adjacent well B1-1 in segments #1, #4, #6, and #8. Conversely, all segments of well B1 exhibit poor connectivity with adjacent well B1-2. The results can provide a dependable reference for optimizing fracturing parameters, well spacing, and productivity evaluation in coal reservoirs. The results obtained in this study are consistent with the results obtained by using the four-dimensional (4D in short) image monitoring technology, which proves the good accuracy and reliability of the micromaterial tracer monitoring method.
RESUMO
To explore novel sources of anti-fatigue drugs and food, the anti-fatigue activity of hemp leaves water extract (HLWE) was investigated through exhaustive swimming tests of mice. The median exhaustion swimming time of mice gavaged with HLWE reached 55.4 min, which was 156.8% and 87.8% longer than that of the control group and Rhodiola group, respectively. Then, several biochemical parameters related to fatigue were determined to explore the possible anti-fatigue reasons. The blood lactic acid concentration of mice in HLWE group was 0.76 mmol/L, which was 24.8% lower than that in the control group. Compared with the control group, the glutathione peroxidases activity of mice in HLWE group increased by 296.2%. Based on the results, HLWE exhibited outstanding anti-fatigue activity through reducing the accumulation of lactic acid and improving the activities of defense antioxidant enzymes. It shows appealing potential for development and utilization as novel anti-fatigue food or drugs.
