A method has been developed for the simultaneous determination of seven low molecular weight organic acids such as tartaric acid,methanoic acid,acetic acid,lactic acid,butanedioic acid,malic acid and citric acid in several beverages by high performance liquid chromatography(HPLC) coupled with liquid phase microextraction(LPME).Effects of extraction solvent,stirring rate,effect of salts,extraction time,temperature,pH of the acceptor phase and given phase on microextraction efficiency were investigated.The optimum experimental conditions were as follows:tributyl phosphate(TBP) as organic solven,stirring rate:1 000 r/min,extraction time:35 min,pH value of donor phase:2.5,pH value of acceptor phase:12.0.The results showed that the proposed method provided a wide linear range with correlation coefficients more than 0.993 6.The detection limits(S/N=3) ranged from 10.4 to 54.2 μg/L,and the RSDs were less than 4.8%.The enrichment folds of seven organic acids were in the range of 13.3-51.4,and their recoveries ranged from 85% to 103%.The method showed the advantages of simplicity,sensitivity,fastness and green for the use of very small amounts of organic solvent.It could be used for the determination of low molecular weight organic acids not only in samples such as juices and tea drinks,but also in milk drinks with complex matrixes.The study provides a useful method for the analysis of samples with complex matrixes.
The distribution law of fluoride ions in groundwater in Daqing City, Lindian County,is discussed.The hydrochemical statistical analysis method and hydrochemical simulation model were used to reveal the generation mechanism.The results were as follows:(1) The groundwater with high fluoride concentration was mostly alkalescent water of TDS,and main water chemistry type is the Na-Mg or Na-Ca type.Fluoride content had a certain correlation with the proportions of the main ions in the groundwater.(2) The accumulation of fluorin ions in the groundwater of the unconfined aquifer was mainly due to the cation exchange and evaporation,but the main formation mechanism of the fluorin ions in the confined aquifer was fluorin mineral dissolution.
In this paper, the color reaction of cadmium with o-nitrophenylflurone (o-NPF) in microemulsion has been studied. In the buffer medium of Borax-NaOH at 10.40, cadmium (Ⅱ) reacts with o-NPF to form a stable 1: 3 complex. Its apparent molar absorptivity is 1.23×10~5 L·mol~(-1)·cm~(-1) at 620 nm. Beer's law is obeyed in the range of 0～0.76μg.mL~(-1). The detection limit is 9.2×10~(-5) μg·mL~(-1). The coexistent metal ions can be separated and cadmium can be enriched by sulfhydryl dextrane gel (SDG), thus, the selectivity and sensibility of system could be improved greatly. The method characterizes with high sensitivity as well as high selectivity and can be used to determine trace amount of cadmium in water and sludge samples successfully.
Generalist predators are characterized as sentinel species because they are conspicuous, occupy top trophic positions of the food chain, and have life history traits that make their trophic information sensitive to ecosystem state alteration. Here, we test if changes in the trophic information of a generalist predator along an eutrophication gradient can be used to determine the regime shift of lake ecosystems between clear and turbid states and provide reliable estimates of their resilience. We find that redfin culter (Chanodichthys erythropterus) trophic information responded differently to eutrophication than traditional indicators. Trophic tipping points, reached at 14.90% coverage of macrophyte, appeared earlier than those of traditional indicators. Further, the hysteresis associated to the predator’s state characterized by prey reliance on benthic fishes of low trophic signature was found to be greater than that of the ‘macrophyte-poor’ turbid state. Conclusively, generalist predators can not only serve as sentinels of the ecosystem, but also be the last barrier to be broken through in restoring the ecosystem.
Objective
To investigate the efficacy and application of bronchoalveolar lavage in children with severe pneumonia undergoing mechanical ventilation.
Methods
Using a prospective randomized controlled clinical study, 202 children with severe pneumonia received mechanical ventilation in Hunan Children′s Hospital from January 2016 to January 2018 were selected as the subjects.According to the digital method, all cases were divided into treatment group (101 cases) and control group (101 cases) randomly.The patients in the control group were given conventional treatment (anti-infection and symptomatic therapy). The treatment group was treated with bronchoalveolar lavage on the basis of conventional treatment.The basic situation, the respiratory function before and after the treatment, the inflammation index, the curative effect and the prognosis of two groups were analyzed.
Results
There were no significant differences between the two groups in gender, age, course pre-admission, pediatric critical illness score, respiratory function and inflammation index (P>0.05). The respiratory function indexes of the treatment group were obviously improved 2 hours after the treatment and the PaO2, PaO2/FiO2 and SaO2 were significantly higher than those of the control group[PaO2: (82.4±6.4) mmHg(1 mmHg=0.133 kPa) vs.(74.0±5.5) mmHg, PaO2/FiO2: (360.2±21.3) mmHg vs.(332.6±23.5) mmHg, SaO2: (94.9±8.2)% vs.(88.6±10.3)%], while the PaCO2 were significantly lower than the control group[(37.3±10.3) mmHg vs.(45.8±5.5) mmHg], and the differences were statistically significant (P 0.05].
Conclusion
The bronchoalveolar lavage can improve the respiratory function, reduce the inflammatory reaction, shorten mechanical ventilation duration and PICU stay in children with severe pneumonia undergoing mechanical ventilation obviously.It is worth popularizing in the PICU because of the improvement of curative effect in these children.
Key words:
Mechanical ventilation; Bronchoalveolar lavage with fiberoptic bronchoscopy; Inflammatory biomarker; Severe pneumonia; Children
Both pyrene and benzo(a)pyrene as experiment materials,multi-genotype indigenous junzhu and introduced strains were simultaneously screened in our lab.The experiment results showed that the introduced strains of after-domestication were capable of degrading ability towards pyrene and benzo(a)pyrene,respectively.The degradation rates were in a range between 30% and 80%.According to our variation analysis by SPSS software,it inferred that the introduced strains B61,B67,M-B and yeast Y219,Y220,M-Y,respectively,were immobilized strains.Degradation rates of indigenous strains to pyrene and benzo(a)pyrene were in a range between 40% and 95%,after screening,while indigenous strains B02,B07,B09 and fungi F02,F05,F06 were immobilized strains.It was also found that the growth curve of the above strains for the period of logarithm growth of bacteria was 8～20 h,and that of fungi was 5～55 h,making it possible to provide precondition of immobilized microorganisms.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
