Acetylcholinesterase （ACHE） plays an important role in enzyme-based detection of pesticides in the environment. In this paper, ACHE from the Triton X-100 extract of brain tissues of Oreochromis aurea was purified by...Acetylcholinesterase （ACHE） plays an important role in enzyme-based detection of pesticides in the environment. In this paper, ACHE from the Triton X-100 extract of brain tissues of Oreochromis aurea was purified by （NH4）2SO4 fractional precipitation, Sephadex G-100 gel filtration, and DEAE-cellulose ion exchange chromatography. Certain biochemical characterizations of the purified enzyme and inhibition of pesticides on the enzyme were also studied. The specific activity of this purified enzyme was 20.628 U/mg protein, fold of purification was 139, and recovery was 22.1%. The optimal temperature of this enzyme was between 35-40 ℃, and optimal pH was between 7.5-8.0. The Michaelis constant （Kin） for acetylthiocholine iodide was 0.183 mmol/L. The enzyme activity was inhibited by excess substrate, and optimal substrate concentration was 6 mmol/L. Four pesticides （dichlorvos, phoxim, triazophos, and methomyl） exhibited strong inhibitions on this enzyme with IC50 less than 5 μg/mL. This study suggests that Oreochromis aurea （tilapia） could be a good enzyme source for pesticide monitoring in water environments.展开更多
Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusions from molten aluminum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic...Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusions from molten aluminum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used to produce pulse gas currents for the rotary impeller degassing method. Water simulation results show that the size of gas bubbles can be decreased by 10%20% as compared with the constant gas current mode. By coating ceramic filters or particles with active flux or enamels, composite filters were used to filter the scrap A356 alloy and pure aluminum. Experimental results demonstrate that better filtration efficiency and operation performance can be obtained. Based on numerical calculations, the separation efficiency of inclusions by high frequency magnetic field can be significantly improved by using a hollow cylinder-like separator or utilizing the effects of secondary flow of the melt in a square separator. A multi-stage and multi-media purification platform based on these methods was designed and applied in on-line processing of molten aluminum alloys. Mechanical properties of the processed scrap A356 alloy are greatly improved by the composite purification.展开更多
The effects of non-flux purification techniques on the mechanical properties and microstructure of AZ91 magnesium alloy were investigated by ICP,OM,XRD and SEM.The results show that Ar spraying with high flow rate cou...The effects of non-flux purification techniques on the mechanical properties and microstructure of AZ91 magnesium alloy were investigated by ICP,OM,XRD and SEM.The results show that Ar spraying with high flow rate could remove non-metallic inclusions and improve the mechanical properties of AZ91.The alloy obtains the best properties after argon spraying for 30 min at the melt temperature of 740 °C.The ceramic foam filter(CFF) could effectively improve the ultimate tensile strength and elongation of AZ91 alloy,especially the elongation,which increase with increasing pores per inch(ppi) and the thickness of CFF.Non-flux purification does not change the microstructure of AZ91 alloy.However,filtration has a certain effect on the fracture pattern of AZ91 alloy.To improve the mechanical properties effectively,both filtration and gas spraying should be utilized together.展开更多
There are many patients in the blood purification center who need maintenance hemodialysis to maintain life. Those patients generally havelow resistance and are easily exposed to coronavirus because they go back and f...There are many patients in the blood purification center who need maintenance hemodialysis to maintain life. Those patients generally havelow resistance and are easily exposed to coronavirus because they go back and forth the hospital and residence three times a week andclosely contact with family, caregivers, community personnel, people in various means of transportation, medical staff, and other patientsvisiting hospital. Therefore, the blood purification center has become a high‑risk environment for the spread of COVID-19 infection. In viewof this, our center quickly responded to the formulation and implementation of infection prevention and control measures suitable for thecharacteristics of the blood purification center and continuous renal replacement therapy (CRRT) emergency plan for fever and suspectedpatients. According to these measures, we have a positive effect on preventing and controlling nosocomial infection in the blood purificationcenter.展开更多
Large-scale production of cell culture-based classical swine fever virus(CSFV)vaccine is hampered by the adverse reactions caused by contaminants from host cell and culture medium.Hence,we have developed an efficient ...Large-scale production of cell culture-based classical swine fever virus(CSFV)vaccine is hampered by the adverse reactions caused by contaminants from host cell and culture medium.Hence,we have developed an efficient method for purifying CSFV from cell-culture medium.Pure viral particles were obtained with two steps of tangential-flow filtration(TFF)and size-exclusion chromatography(SEC),and were compared with particles from ultracentrifugation by transmission electron microscopy(TEM),infectivity and recovery test,and real time fluorescent quantitative PCR(FQ-PCR).TFF concentrated the virus particles effectively with a retention rate of 98.5%,and 86.2%of viral particles were obtained from the ultrafiltration retentate through a Sepharose 4 F F column on a biological liquid chromatography system.CSFV purified by TFF-SEC or ultracentrifugation were both biologically active from 1.0×10–4.25 TCID50·mL^(–1) to 3.0×10^(–6.25) TCID50·mL^(–1),but the combination of TFF and SEC produced more pure virus particles than by ultracentrifugation alone.In addition,pure CSFV particles with the expected diameter of 40–60 nm were roughly spherical without any visible contamination.Mice immunized with CSFV purified by TFF-SEC produced higher antibody levels compared with immunization with ultracentrifugation-purified CSFV(P<0.05).The purification procedures in this study are reliable technically and feasible for purification of large volumes of viruses.展开更多
Tangential fiow filtration (TFF) is a purification method commonly used in a multitude of fields,including particle engineering.Currently,there is still a lack of comprehensive understanding of the effects of key TFF ...Tangential fiow filtration (TFF) is a purification method commonly used in a multitude of fields,including particle engineering.Currently,there is still a lack of comprehensive understanding of the effects of key TFF parameters on nanoparticle (NP) characteristics (purification outcomes).The present study aimed to investigate the influence of various factors on the characteristics of TFF-purified NP.The most commonly used NP purification method,centrifugation,was studied as a control.A design of experiment approach was implemented to investigate the influence of transmembrane pressure,flow rate,and initial drug loading on NP characteristics using paclitaxel as a model small molecule.Following the determination of optimized TFF parameters,the two purification methods were assessed using other model small molecules (i.e.tacrolimus and resveratrol).The results indicated that the TFF parameters and initial loading of the drug played important roles in the purified NP outcomes.Compared with the centrifugation method,TFF resulted in smaller NP with higher drug loading.TFF was able to circumvent issues associated with conventional centrifugation,while yielding similar results,and can potentially serve as a suitable large-scale purification method for polymeric NP.展开更多
基金supported by Huizhou Science and Technology Planning Project Foundation (Grant No.2008P60)
文摘Acetylcholinesterase （ACHE） plays an important role in enzyme-based detection of pesticides in the environment. In this paper, ACHE from the Triton X-100 extract of brain tissues of Oreochromis aurea was purified by （NH4）2SO4 fractional precipitation, Sephadex G-100 gel filtration, and DEAE-cellulose ion exchange chromatography. Certain biochemical characterizations of the purified enzyme and inhibition of pesticides on the enzyme were also studied. The specific activity of this purified enzyme was 20.628 U/mg protein, fold of purification was 139, and recovery was 22.1%. The optimal temperature of this enzyme was between 35-40 ℃, and optimal pH was between 7.5-8.0. The Michaelis constant （Kin） for acetylthiocholine iodide was 0.183 mmol/L. The enzyme activity was inhibited by excess substrate, and optimal substrate concentration was 6 mmol/L. Four pesticides （dichlorvos, phoxim, triazophos, and methomyl） exhibited strong inhibitions on this enzyme with IC50 less than 5 μg/mL. This study suggests that Oreochromis aurea （tilapia） could be a good enzyme source for pesticide monitoring in water environments.
文摘Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusions from molten aluminum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used to produce pulse gas currents for the rotary impeller degassing method. Water simulation results show that the size of gas bubbles can be decreased by 10%20% as compared with the constant gas current mode. By coating ceramic filters or particles with active flux or enamels, composite filters were used to filter the scrap A356 alloy and pure aluminum. Experimental results demonstrate that better filtration efficiency and operation performance can be obtained. Based on numerical calculations, the separation efficiency of inclusions by high frequency magnetic field can be significantly improved by using a hollow cylinder-like separator or utilizing the effects of secondary flow of the melt in a square separator. A multi-stage and multi-media purification platform based on these methods was designed and applied in on-line processing of molten aluminum alloys. Mechanical properties of the processed scrap A356 alloy are greatly improved by the composite purification.
基金Project(08XD14020) supported by the Program of Shanghai Subject Chief Scientist,ChinaProject(2007CB613701) supported by the National Basic Research Program of ChinaProject(2009AA033501) supported by the National High-tech Research and Development Program of China
文摘The effects of non-flux purification techniques on the mechanical properties and microstructure of AZ91 magnesium alloy were investigated by ICP,OM,XRD and SEM.The results show that Ar spraying with high flow rate could remove non-metallic inclusions and improve the mechanical properties of AZ91.The alloy obtains the best properties after argon spraying for 30 min at the melt temperature of 740 °C.The ceramic foam filter(CFF) could effectively improve the ultimate tensile strength and elongation of AZ91 alloy,especially the elongation,which increase with increasing pores per inch(ppi) and the thickness of CFF.Non-flux purification does not change the microstructure of AZ91 alloy.However,filtration has a certain effect on the fracture pattern of AZ91 alloy.To improve the mechanical properties effectively,both filtration and gas spraying should be utilized together.
文摘There are many patients in the blood purification center who need maintenance hemodialysis to maintain life. Those patients generally havelow resistance and are easily exposed to coronavirus because they go back and forth the hospital and residence three times a week andclosely contact with family, caregivers, community personnel, people in various means of transportation, medical staff, and other patientsvisiting hospital. Therefore, the blood purification center has become a high‑risk environment for the spread of COVID-19 infection. In viewof this, our center quickly responded to the formulation and implementation of infection prevention and control measures suitable for thecharacteristics of the blood purification center and continuous renal replacement therapy (CRRT) emergency plan for fever and suspectedpatients. According to these measures, we have a positive effect on preventing and controlling nosocomial infection in the blood purificationcenter.
基金the Special Fund for Agro-scientific Research in the Public Interest(201203039)China Agriculture Research System(CARS-36).
文摘Large-scale production of cell culture-based classical swine fever virus(CSFV)vaccine is hampered by the adverse reactions caused by contaminants from host cell and culture medium.Hence,we have developed an efficient method for purifying CSFV from cell-culture medium.Pure viral particles were obtained with two steps of tangential-flow filtration(TFF)and size-exclusion chromatography(SEC),and were compared with particles from ultracentrifugation by transmission electron microscopy(TEM),infectivity and recovery test,and real time fluorescent quantitative PCR(FQ-PCR).TFF concentrated the virus particles effectively with a retention rate of 98.5%,and 86.2%of viral particles were obtained from the ultrafiltration retentate through a Sepharose 4 F F column on a biological liquid chromatography system.CSFV purified by TFF-SEC or ultracentrifugation were both biologically active from 1.0×10–4.25 TCID50·mL^(–1) to 3.0×10^(–6.25) TCID50·mL^(–1),but the combination of TFF and SEC produced more pure virus particles than by ultracentrifugation alone.In addition,pure CSFV particles with the expected diameter of 40–60 nm were roughly spherical without any visible contamination.Mice immunized with CSFV purified by TFF-SEC produced higher antibody levels compared with immunization with ultracentrifugation-purified CSFV(P<0.05).The purification procedures in this study are reliable technically and feasible for purification of large volumes of viruses.
文摘Tangential fiow filtration (TFF) is a purification method commonly used in a multitude of fields,including particle engineering.Currently,there is still a lack of comprehensive understanding of the effects of key TFF parameters on nanoparticle (NP) characteristics (purification outcomes).The present study aimed to investigate the influence of various factors on the characteristics of TFF-purified NP.The most commonly used NP purification method,centrifugation,was studied as a control.A design of experiment approach was implemented to investigate the influence of transmembrane pressure,flow rate,and initial drug loading on NP characteristics using paclitaxel as a model small molecule.Following the determination of optimized TFF parameters,the two purification methods were assessed using other model small molecules (i.e.tacrolimus and resveratrol).The results indicated that the TFF parameters and initial loading of the drug played important roles in the purified NP outcomes.Compared with the centrifugation method,TFF resulted in smaller NP with higher drug loading.TFF was able to circumvent issues associated with conventional centrifugation,while yielding similar results,and can potentially serve as a suitable large-scale purification method for polymeric NP.
