A large-scale, thin wall duplex stainless steel impeller with complex geometry was deformed severely and unpredictably during casting and heat treatment processes resulted in dimensional failure for the final part. In...A large-scale, thin wall duplex stainless steel impeller with complex geometry was deformed severely and unpredictably during casting and heat treatment processes resulted in dimensional failure for the final part. In this paper, the distortion of the impeller during casting and heat treatment was calculated. A commercial software, Experto-ViewCast, was used to simulate the transient heat transfer, solidification and mechanical behaviors during the casting and the heat treatment process. The coupled set of governing differential equations for mass, energy and mechanical balance were solved by finite control volume and finite element method. A thermoelastic-visco-plastic rheological model was used to compute the constrained shrinkage of the casting. At each time increment, a coupling of the heat transfer and mechanics was performed. Comparison of the experimental measurements with the model predictions showed good agreement. From the calculated displacements of key points of the blade, the proper inverse displacements were determined to provide an optimum casting pattern and to achieve a uniform and reasonable machining allowance for both faces of the blade.展开更多
Objective To evaluate the combined subchronic toxicity of bisphenol A（BPA） and dibutyl phthalate（DBP） in male Sprague Dawley（SD） rats.Methods Forty 4‐week‐old male rats weighing 115‐125 g were randomly divide...Objective To evaluate the combined subchronic toxicity of bisphenol A（BPA） and dibutyl phthalate（DBP） in male Sprague Dawley（SD） rats.Methods Forty 4‐week‐old male rats weighing 115‐125 g were randomly divided into BPA‐treated,DBP‐treated group,BPA＋DBP‐treated and control groups and fed with a soy‐ and alfalfa‐free diet containing 285.4 ppm BPA,285.4 ppm DBP,285.4 ppm BPA plus 285.4 ppm DBP,and a control diet,respectively,for 90 consecutive days.At the end of the study,the animals were sacrificed by exsanguination via the carotid artery under diethyl etherane aesthesia and weighed.Organs,including liver,kidneys,spleen,thymus,heart,brain,and testis underwent pathological examination.The androgen receptor（AR）,gonadotropin‐releasing hormone receptor（GNRHR）,and progesterone hormone receptor（PR） genes from the hypothalamus were detected by real‐time PCR.The biomedical parameters were analyzed.Results No significant difference was found in food intake,body weight,tissue weight,organ/brain weight ratio,and biomedical parameters among the four groups（P〉0.05）.However,BPA and DBP up‐regulated AR,PR and GNRHR expression levels in rats and showed a synergistic or an additive effect in the BPA＋DBP group.Conclusion The combined subchronic toxicity of BPA and DBP is synergistic or additive in male SD rats.展开更多
Objective To evaluate the androgenic and anti-androgenic effects of GH （growth hormone） transgenic carp in male rats.Methods Hershberger assay was carried out in castrated male SD rats aged 4-5 weeks.Testosterone pr...Objective To evaluate the androgenic and anti-androgenic effects of GH （growth hormone） transgenic carp in male rats.Methods Hershberger assay was carried out in castrated male SD rats aged 4-5 weeks.Testosterone propionate （TP） （0.4 mg/kg BW） was administrated for a positive control,GH transgenic carp （3.0 g/kg BW）＋TP （0.4 mg/kg BW）,parental carp （3.0 g/kg BW） ＋ TP （0.4 mg/kg BW）,and flutamide （Flu） （3.0 g/kg BW） were used for negative controls,and vehicle was administered orally for a blank control.All groups were administrated for 10 consecutive days.At the end of the test,animals were anesthetized,then weights of accessory sex organ were measured.Serum testosterone （T）,luteinizing hormone （LH）,and Follicle-Stimulating Hormone （FSH） levels were detected.Results The weights ratios of the accessory sex organs and body weights showed no significant differences between the solvent control and the GH transgenic carp-treated groups.Serum concentrations of FSH,LH,and T of the rats treated with GH transgenic carp ＋ TP showed no significant changes,compared with those treated with TP only.Conclusion GH transgenic carp does not have any androgenic agonist or antagonist properties in vivo screening tests.展开更多
Advantame,with the chemical name N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-α-aspartyl]L-phenylalanine 1-methyl ester,monohydrate,is an artificial sweetener made by a chemical reaction between vanillin and aspartame,...Advantame,with the chemical name N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-α-aspartyl]L-phenylalanine 1-methyl ester,monohydrate,is an artificial sweetener made by a chemical reaction between vanillin and aspartame,which are both permitted as flavoring and food additives by the China National Food Safety Standard-Standards for Use of Food Additives(GB 2760).As an intense sweetener,advantame is approximately 90-120times sweeter than aspartame and approximately14,000-48,000 times sweeter than saccharose.展开更多
The method has been developed to accurately identify the magnitude of health risks and provide scientific evidence for implementation of risk management in food safety.It combines two parameters including consequence ...The method has been developed to accurately identify the magnitude of health risks and provide scientific evidence for implementation of risk management in food safety.It combines two parameters including consequence and likelihood of adverse effects based on risk matrix.Score definitions and classification for the consequence and the likelihood of adverse effects are proposed.The risk score identifies the intersection of consequence and likelihood in risk matrix represents its health risk level with different colors：‘low＇,‘medium＇,‘high＇.Its use in an actual case is shown.展开更多
文摘A large-scale, thin wall duplex stainless steel impeller with complex geometry was deformed severely and unpredictably during casting and heat treatment processes resulted in dimensional failure for the final part. In this paper, the distortion of the impeller during casting and heat treatment was calculated. A commercial software, Experto-ViewCast, was used to simulate the transient heat transfer, solidification and mechanical behaviors during the casting and the heat treatment process. The coupled set of governing differential equations for mass, energy and mechanical balance were solved by finite control volume and finite element method. A thermoelastic-visco-plastic rheological model was used to compute the constrained shrinkage of the casting. At each time increment, a coupling of the heat transfer and mechanics was performed. Comparison of the experimental measurements with the model predictions showed good agreement. From the calculated displacements of key points of the blade, the proper inverse displacements were determined to provide an optimum casting pattern and to achieve a uniform and reasonable machining allowance for both faces of the blade.
基金supported by the National Key Technology R&D Program(No.2012BAK01B00)
文摘Objective To evaluate the combined subchronic toxicity of bisphenol A（BPA） and dibutyl phthalate（DBP） in male Sprague Dawley（SD） rats.Methods Forty 4‐week‐old male rats weighing 115‐125 g were randomly divided into BPA‐treated,DBP‐treated group,BPA＋DBP‐treated and control groups and fed with a soy‐ and alfalfa‐free diet containing 285.4 ppm BPA,285.4 ppm DBP,285.4 ppm BPA plus 285.4 ppm DBP,and a control diet,respectively,for 90 consecutive days.At the end of the study,the animals were sacrificed by exsanguination via the carotid artery under diethyl etherane aesthesia and weighed.Organs,including liver,kidneys,spleen,thymus,heart,brain,and testis underwent pathological examination.The androgen receptor（AR）,gonadotropin‐releasing hormone receptor（GNRHR）,and progesterone hormone receptor（PR） genes from the hypothalamus were detected by real‐time PCR.The biomedical parameters were analyzed.Results No significant difference was found in food intake,body weight,tissue weight,organ/brain weight ratio,and biomedical parameters among the four groups（P〉0.05）.However,BPA and DBP up‐regulated AR,PR and GNRHR expression levels in rats and showed a synergistic or an additive effect in the BPA＋DBP group.Conclusion The combined subchronic toxicity of BPA and DBP is synergistic or additive in male SD rats.
基金supported by a grant from the Major State Basic Research Development Program of China (973 Program) (2007CB109207)
文摘Objective To evaluate the androgenic and anti-androgenic effects of GH （growth hormone） transgenic carp in male rats.Methods Hershberger assay was carried out in castrated male SD rats aged 4-5 weeks.Testosterone propionate （TP） （0.4 mg/kg BW） was administrated for a positive control,GH transgenic carp （3.0 g/kg BW）＋TP （0.4 mg/kg BW）,parental carp （3.0 g/kg BW） ＋ TP （0.4 mg/kg BW）,and flutamide （Flu） （3.0 g/kg BW） were used for negative controls,and vehicle was administered orally for a blank control.All groups were administrated for 10 consecutive days.At the end of the test,animals were anesthetized,then weights of accessory sex organ were measured.Serum testosterone （T）,luteinizing hormone （LH）,and Follicle-Stimulating Hormone （FSH） levels were detected.Results The weights ratios of the accessory sex organs and body weights showed no significant differences between the solvent control and the GH transgenic carp-treated groups.Serum concentrations of FSH,LH,and T of the rats treated with GH transgenic carp ＋ TP showed no significant changes,compared with those treated with TP only.Conclusion GH transgenic carp does not have any androgenic agonist or antagonist properties in vivo screening tests.
基金supported by the National Key Research and Development Program [No.2018YFC1603300]the Beijing Key Laboratory for Quality Evaluation Technology of Hygiene and Safety of Plastics(Beijing Technology and Business University)Open Fund Project [No.QETHSP2018002]
文摘Advantame,with the chemical name N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-α-aspartyl]L-phenylalanine 1-methyl ester,monohydrate,is an artificial sweetener made by a chemical reaction between vanillin and aspartame,which are both permitted as flavoring and food additives by the China National Food Safety Standard-Standards for Use of Food Additives(GB 2760).As an intense sweetener,advantame is approximately 90-120times sweeter than aspartame and approximately14,000-48,000 times sweeter than saccharose.
基金supported by the Health and Family Planning Commission&National Major Scientific and Technological Special Project(2014ZX09304307)
文摘The method has been developed to accurately identify the magnitude of health risks and provide scientific evidence for implementation of risk management in food safety.It combines two parameters including consequence and likelihood of adverse effects based on risk matrix.Score definitions and classification for the consequence and the likelihood of adverse effects are proposed.The risk score identifies the intersection of consequence and likelihood in risk matrix represents its health risk level with different colors：‘low＇,‘medium＇,‘high＇.Its use in an actual case is shown.
