PubMed Health⌕ Search

Biomedical subjects

Yi Qian

Publications and source records attributed to Yi Qian.

At least 37 records · Page 2Linked to original sources
PubMed2005

Effect of nitrogen concentration in culture mediums on growth and enzyme production of Phanerochaete chrysosporium.

Effect of different nitrogen concentration in the mediums on growth and enzyme production of Phanerochaete chrysosporium was studied when glucose concentration was 10 g/L. The results showed that the medium contained 0.8 g/L ammonium tartrate is the best. It not only supply abundant nutrients for the growth of Phanerochaete chrysosporium, which make mycelia the best grow compared with the other medium, but also produce higher manganese-dependent peroxidase (Mnp) and laccase (Lac) activity. In addition, it is observed that the variation of mycelia surface is related to ligninolytic enzyme secreted by Phanerochaete chrysosporium. When the surface of mycelium pellets appeared burs, it predicts secondary metabolism begin. This experimentation demonstrated that when the ratio of carbon and nitrogen in nitrogen limited medium is equal to 100:8, growth and enzyme production of Phanerochaete chrysosporium is the best, it could achieve the maximum Mnp and Lac activity.

Biomass↗
PubMed2005

[Effect of environment and nutrient factors on the content of nitrogen and phosphorus in two duckweeds species: Spirodela polyrrhiza and Lemna aequinoctialis].

Effects of temperature, light density, nitrogen level and phosphorus level of medium to the content of two species Spirodela polyrrhiza and Lemna aequinoctialis were researched. The results showed that the content of nitrogen in two species kept constant when the concentration of nitrogen was higher than 3 mg x L(-1) and temperature higher than 25 degrees C. It decreased under lower concentrations of nitrogen and lower temperature. Photon flux density had no effect on it. But weak photon flux density and low temperature led to reduce the content of phosphorus of duckweed. The content of phosphorus in two duckweed species kept constant when photon flux density was higher than 8 000 1x and temperature higher than 25 degrees C. The relationship between the content of phosphorus and concentrations of phosphorus in medium could be described by Monod model. The saturated phosphorus content of Spirodela polyrrhiza was higher than Lemna aequinoctialis.

Araceae↗
PubMed2005

[Effect of pH on suppressing the growth of other bacteria and fungi in culturing Phanerochaete chrysosporium in liquid medium].

Effect of different pH value on suppressing the growth of other bacteria and fungi in culturing Phanerochaete chrysosporium in liquid medium under non-sterile were investigated in agitated Erlenmeyer flasks. Results showed that nitrogen-limited liquid medium with pH3.6 and pH4.4 were contaminated only by yeast fungi when the Phanerochaete chrysosporium was incubated with spore inoculation under non-sterile condition for one day; however, nitrogen-limited liquid medium with pH5.6 was contaminated not only by yeast, but also by bacteria. These contaminated yeast and bacteria reduced the dye decolorizing ability of Phanerochaete chrysosporium . If after the Phanerochaete chrysosporium was incubated under sterile condition for 5 days, it can decolorize over 70% of the reactive brilliant red K-2BP within 45 hours under non-sterile condition, and this removal rate was close to or even higher than that under sterile condition. Phanerochaete chrysosporium cultured in the liquid medium with pH4.4 have the best decolorizing effect under non-sterile condition, and can decolorize up to 80% of the reactive brilliant red K-2BP in 24 hours. In additions, it was observed that by using the Phanerochaete chrysosporium incubated in above nitrogen-limited liquid medium with different pH under sterile condition for 5 days, the system were also contaminated by the other bacteria and yeast during decolorizing reactive brilliant red K-2BP under non-sterile condition, but the amount of these bacteria and yeast in liquid medium were too little to influence the Phanerochaete chrysosporium decolorizing reactive brilliant red K-2BP. So that, when Phanerochaete chrysosporium was used to decolorize reactive dyes under non-sterile condition, the incubation of Phanerochaete chrysosporium must be operated under sterile condition in order to achieve the higher decolorization.

Bacteria↗
PubMed2004

Enhancement of 2,4-dichlorophenol degradation in conventional activated sludge systems bioaugmented with mixed special culture.

Efficient and reliable removal of recalcitrant compounds, which are present in wastewater intermittently, is critically important to prevent toxicity discharge and system upset, especially for those biotreatment systems with poor anti-shock loading capacity such as conventional activated sludge (CAS) systems. In this study, 2,4-dichlorophenol (2,4-DCP) was chosen as a model recalcitrant substance. 2,4-DCP degrading mixed culture was bioaugmented to a CAS system in terms of enhancing 2,4-DCP removal and maintaining system stability under shock loading conditions. The effects of bioaugmentation on the performance of CAS systems after single inoculation were investigated under long-term continuous operation, during which four times shock loading occurred. Results showed that the two bioaugmented CAS systems, which were inoculated with 5% and 15% 2,4-DCP degrading mixed culture, respectively, demonstrated and maintained stronger ability to degrade 2,4-DCP than the non-supplemented control one during the first three shock loading periods within the first month after the first inoculation. For the fourth 2,4-DCP shock loading which occurred 100 days after inoculation, the advantages demonstrated by the bioaugmented systems were greatly reduced compared to those of the previous three runs. In addition, ribosomal intergenic spacer analysis method was used to track the supplemented special culture and assay the effect of bioaugmentation on the changes of microbial community structure.

Anthelmintics↗
PubMed2004

Experimental determination of dynamic characteristics of the VentrAssist implantable rotary blood pump.

The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump consists of a shaftless impeller, which also acts as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, which result from the small clearances between the outside surfaces of the impeller and the pump cavity. These small clearances range from approximately 50 microm to 230 microm in size in the version of pump reported here. This article presents experimental investigation into the dynamic characteristics of the impeller-bearing-pump housing system of the rotary blood pump for increasing pump speeds at different flow rates. The pump was mounted on a suspension system consisting of a platform and springs, where the natural frequency and damping ratio for the suspension system were determined. Real-time measurements of the impeller's displacement were performed using Hall effect sensors. A vertical disturbance force was exerted onto the pump housing, causing the impeller to be displaced in vertical direction from its dynamic equilibrium position within the pump cavity. The impeller displacement was represented by a decaying sine wave, which indicated the impeller restoring to its equilibrium position. From the decaying sine wave the natural frequency and stiffness coefficient of the system were determined. Furthermore, the logarithmic decrement method was used to determine the damping ratio and eventually the damping coefficient of the system. Results indicate that stiffness and damping coefficients increased as flow rate and pump speed increased, representing an increase in stability with these changing conditions. However, pump speed had a greater influence on the stiffness and damping coefficients than flow rate did, which was evident through dynamic analysis. Overall the experimental method presented in this article was successful in determining the dynamic characteristics of the system.

Blood Flow Velocity↗
PubMed2004

Using a zeolite medium biofilter to remove organic pollutant and ammonia simultaneously.

A pilot scale zeolite medium biological aerated filter(ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand(COD), ammonia-N and turbidity to satisfied degree at a hydraulic retention time(HRT) of 0.95 h. Their average removal efficiencies were 73.9%, 88.4% and 96.2% with the corresponding average effluent concentrations of 43.4 mg/L, 3.5 mg/L and 3.7 NTU, respectively. These effluent items met with the water quality standard of the treated water reused for cooling water. The COD removal volumetric loading rate increased proportionally with its applied volumetric loading rate with its maximum of 7.1 kg/(m3 x d). Ammonia-N removal loading rate also increased proportionally with its applied loading rate at HRT of longer than 0.95 h and the feasible maximum removal loading rate was 0.9 kg/(m3 x d). The COD loading rate did not affect the ammonia-N removal efficiency significantly when it was lower than 5.5 kg/(m3 x d). ZBAF has good application prospect for its low cost and high removal efficiency in the future.

Ammonia↗
PubMed2004

[Inhibition of aromatics on ammonia-oxidizing activity of sediment].

The inhibition of 24 aromatics on ammonia-oxidizing activity of nitrifying bacteria in sediment was measured. The effects of the kind, number and position of substituted groups on ammonia-oxidizing activity of nitrifying bacteria were discussed. The inhibition of mono-substituted benzenes on ammonia-oxidizing activity of nitrifying bacteria were in order of -OH > -NO2 > -NH2 > -Cl > -CH3 > -H. The position of substituted groups of di-substituted benzenes also affected the inhibition, and the inhibitions of dimethylbenzenes(xylene) were in order of meta-> ortho-> para-. The increase in number of substituted group on benzene-ring enhanced the inhibition of aromatics studied in this study on nitrifying bacteria. There was a linear relationship between inhibition (IC50, mumol.L-1) of aromatics on ammonia-oxidizing activity and total electronegativity (sigma E) of aromatics: lgIC50 = 14.72 - 0.91 sigma E.

Ammonia↗
PubMed2004

[Movement and transformation of nitrate in soil by non-uniform electrokinetics].

Movement and accumulation of nitrate in soil and groundwater has become a serious threat in many cities and agricultural areas. At the same time, application of nitrate as bacterial nitrogenous nutrient in the in-situ bioremediation of some organics-polluted sites is often required. Laboratory experiments were conducted to examine the feasibility of using non-uniform electrokinetics (NUEK) to control the movement of nitrate in unsaturated soil-water system. A natural soil taken from woodland was used as experimental soil. Three electrokinetic processes were tested in bench-scale cells at a constant potential gradient of 1.0 V/cm: unidirectional NUEK, NUEK with periodic polarity-reversal, and conventional uniform electrokinetic (UEK). The tests showed that NUEK drove NO3- through the experimental soil at a rate of 13.5-20 cm/d depending upon the concentration of NO3- and the distribution of electric field density. Compared with UEK, NUEK process more effectively concentrated and retained NO3- close to the anode. Moreover, NUEK process maintained soil characteristics and consumed much less electric energy. Reversal the polarity of NUEK weakened the concentration of NO3- to electrodes, but it stimulated the transformation of NO3- to NO2- and further lowered the electric energy consumption.

Electricity↗
PubMed2004

[Joint inhibition of benzene and monosubstituted benzenes on ammonia-oxidizing activity of sediment].

The joint inhibitions of benzene and three kinds of monosubstituted benzenes (aniline, phenol and nitrobenzene) on ammonia-oxidizing activity of sediment was investigated in order to study the effects of combined pollutants on nitrification process in the nitrogen cycle. The results showed that the joint inhibiton of 11 different kinds of mixtures, including binary or multi-equitoxic mixtures among benzene, aniline, phenol and nitrobenzene, exhibited different effects on ammonia-oxidizing activity of sediment, among which seven were addictive effect, three were synergistic, and only the mixture of benzene and phenol was antagonism. A conclusion could be made that the addition of nitrobenze to a mixture usually exhibited addictive effect. There was a relationship between the half joint inhibition concentrations (IC50, micromol x L(-1)) of benzene and monosubstituted benzenes on ammonia-oxidizing activity of sediment and the mixed electronegativities (MEs): lgIC50 = 2.197 - 0.236ME. With the increase of mixed electronegativities (MEs), the joint inhibitions of mixtures increased.

Ammonia↗
PubMed2004

Bioremediation of quinoline-contaminated soil using bioaugmentation in slurry-phase reactor.

OBJECTIVE: To investigate the possibility of using bioaugmentation as a strategy for remediating quinoline-contaminated soil. METHODS: Microorganisms were introduced to the soil to assess the feasibility of enhancing the removal of quinoline from quinoline-contaminated soil. Slurry-phase reactor was used to investigate the bioremediation of quinoline-contaminated soil. HPLC (Hewlett-Packard model 5050 with an UV detector) was used for analysis of quinoline concentration. RESULTS: The biodegradation rate of quinoline was increased through the introduction of Burkholderia pickettii. Quinoline, at a concentration of 1 mg/g soil, could be removed completely within 6 and 8 hours with and without combined effect of indigenous microbes, respectively. Although the indigenous microbes alone had no quinoline-degrading ability, they cooperated with the introduced quinoline-degrader to remove quinoline more quickly than the introduced microbes alone. Bioaugmentaion process was accelerated by the increase of inoculum size and bio-stimulation. The ratio of water to soil in slurry had no significant impact on bioremediation results. CONCLUSION: Bioaugmetation is an effective way for bioremediation of quinoline-contaminated soil.

Biodegradation, Environmental↗
PubMed2004

[Enhancing resistance of a conventional activated sludge system against shock loading of 2,4-DCP through bioaugmentation with special culture].

In this study, conventional activated sludge (CAS) systems, which were generally used to treat municipal wastewater, were modeled to receive intermittent 2,4-dichlorophenol (2,4-DCP) shock loadings. The response and stability of the CAS system augmented with special culture and the non-bioaugmented control CAS system under shock loading conditions were compared. The capability of the bioaugmented CAS systems to degrade 2,4-DCP under long-term continuous operation was investigated. Results showed that for the CAS systems with 5% and 15% special culture addition, their degradation of the target pollutants and resistance against shock loadings was enhanced significantly. When 2,4-DCP shock loading occurred within the first 30 days after single inoculation, the bioaugmented CAS systems maintained high degradation ability to the target pollutants. After 70 days continuous operation without 2,4-DCP in feed, when the CAS systems challenged 2,4-DCP again, the effect of bioaugmentation was greatly reduced and the CAS system failed to remove the pollutants and maintain the system stability effectively. Therefore, re-supplementation was needed for further treatment of 2,4-DCP.

Bacteria, Anaerobic↗
PubMed2004

[Cultivation of aerobic granular sludge in SBR by seeding anaerobic granular sludge].

Anaerobic granular sludge was inoculated to an aerobic SBR, where CH3COONa was used as the carbon source. Observations on the change of granules' shape and structure revealed that the granules experienced a shape-keeping and component-replacing process. The sludge concentration increased at first 4 weeks and then decreased to reach a constant of 5g/L at 35d with its SVI of 30 - 40mL/g. Granular sludge dominated in the reactor and suspended sludge concentration was less than 0.5g/L during the end of the process. Anaerobic granular sludge, in which spheral bacteria was the main microorganism, was successfully developed to aerobic granular sludge in which filamentous and bacillius bacteria were the dominant microorganism.

Bacteria, Aerobic↗
PubMed2004

Succession of aquatic microbial communities as a result of the water quality variations in continuous water.

The changes of structural and functional parameters of aquatic microbial communities in continuous water on campus of Tsinghua University, China are investigated, by polyurethane foam unit (PFU) method. The measured compositions of the communities include alga, protozoa, and some metazoa (such as rotifers). The measured indicators of water quality include water temperature, pH value, dissolved oxygen (DO), potassium permanganate index (COD(Mn)), total nitrogen (TN), total phosphorus (TP) and chlorophyll-a (Chla). The trophic level, expressed by the trophic level indices (TLIc), is assessed with analytic hierarchy process and principal component analysis (AHP-PCA) method. The changing trends of the structural and functional parameters of aquatic microbial communities, such as Margalef index of diversity (D), Shannon-weaver index of diversity (H), Heterotropy index (HI), number of species when the colonization gets equilibrium (S(eq)), colonizing speed constant (G) and time spent when 90 percent of S(eq) colonized in PFU (T(80%)), are also analyzed. The experimental results showed the succession of aquatic microbial communities along the water flow is consistent with the water quality changes, so the parameters of microbial community can reflect the changes of water quality from the ecological view.

Animals↗
PubMed2004

[Growth feature of biomass of Lemna aequinoctialis and Spirodela polyrrhiza in medium with nutrient character of wastewater].

Duckweeds have an important potential in nutrient recovery from wastewater because of their rapid multiplication and high protein content in biomass. The growth rate of duckweed biomass has a direct relationship with nutrient removal and recovery. With laboratory experiments of batch culture and continuous culture, the growth curves of two duckweed species, Lemna aequinoctialis and Spirodela polyrrhiza, cultivated in different media were gotten and fitted by Logistic model. The effect of nitrogen on growth of duckweed was evaluated. Experimental results indicated that the growth curve had characteristic of sigmoidal shape and the growth rate had density-dependent characteristic. Results of statistical analysis demonstrated that Logistic model is suitable to describe the growth of single duckweed specie. The maximal growth rate from regression in medium with ammonia nitrogen was lower than those in medium with nitrate nitrogen. The maximal growth rate of Lemna aequinoctialis was higher than Spirodela polyrrhiza The paper also discussed the application of Logistic model in harvesting of duckweed biomass from wastewater.

Araceae↗
PubMed2003

Biodegradation of 2,4-dichlorophenol in sequencing batch reactors augmented with immobilized mixed culture.

2,4-Dichlorophenol (2,4-DCP) degrading mixed culture was immobilized in polyvinyl alcohol jel beads and supplemented to sequencing batch reactors (SBR) to treat 2,4-DCP containing wastewater. Impacts of bioaugmentation level on the performance of bioaugmented systems were studied. Results show that inoculum size affected the start-up time of the SBR systems. For the non-augmented SBR system, nine days was needed for the system to start-up, whereas it only took six, four, three and two days for the SBRs with 1.9%, 3.7%, 5.6% and 9.3% immobilized culture, respectively. In addition, bioaugmented SBR systems demonstrated stronger capacity to cope with high 2,4-DCP shock loading than the control system. The control SBR failed to treat 2,4-DCP at 166 mg/l in influent, while the SBR with 1.9% inoculation could successfully cope with 2,4-DCP at 166 mg/l, but failed at 250 mg/l, and the SBR with 3.7%, 5.6% and 9.3% immobilized culture could successfully degrade 250 mg/l 2,4-DCP in feed. Furthermore, the contributions to the removal of 2,4-DCP by the introduced and indigenous culture in an augmented SBR system at various operation stages were investigated. It was found that augmented culture played the primary role in degrading 2,4-DCP at the beginning of system start-up, but after one-month operation, both the indigenous and the introduced culture posed strong ability to degrade 2,4-DCP.

Anthelmintics↗
PubMed2003

[Effects of phenol presence on the biodegradation of 2,4-dichlorophenol in a bioaugmented system].

Special culture for 2,4-Dichlorophenol(2,4-DCP) degradation were supplemented to an activated sludge system and the effects of the presence of phenol at various concentration on the removal of 2,4-DCP were studied. In addition, the changes of the removal rate of 2,4-DCP and phenol under the long existence of phenol was investigated in semicontinuous test. Results show than the presence of phenol at the concentration of 10 mg/L, 50 mg/L, 100 mg/L and 300 mg/L inhibit the biodegradation of 2,4-DCP and the inhibition increased with increasing of phenol concentration. 2, 4-DCP biodegradation rate declined with the run of semi-continuous test, while the biodegradation rate of phenol was much faster than the first run.

Bacteria↗
PubMed2003

[Study on ability of nitrification in a subsurface constructed wetland system treating sewage].

The nitrification ability of different layers in a subsurface constructed wetland treating sewage was measured. The experiment results showed that the ability of nitrification was decreased along the direction of water flow in the subsurface wetland. The constants of ammonia oxidation rate and nitrite oxidation rate in the slag layer on the bottom were 1.99-6.89 mg.(h.kg)-1 and 1.14-5.22 mg.(h.kg)-1 respectively, but in the soil layer on the top were 0.53-0.89 mg.(h.kg)-1 and 0.96-1.39 mg.(h.kg)-1 respectively. So the ability of nitrification in the layer of slag was better than the layer of soil obviously, and it showed that the nitrification was mainly happened in the slag layer.

Ammonia↗