Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal...Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal fan.Design charts were applied to predict noise reduction and length of a dissipative silencer.Dissipative silencers with various punched duct porosity(14%,30%and 40%)and sound absorbent density(80 Kg/m^(3),120 Kg/m^(3),and 140 Kg/m^(3))were designed and fabricated.According to ISO9612 and ISO11820,noise level was measured before and after installing all nine test silencers at fixed workstations around the discharge side of a centrifugal fan in a manufacturing plant.On average,the noise level at the discharge side of a fan without silencer was measured to be 93.6 dBA,whereas it was significantly mitigated by 67.4 dBA to 70.1 dBA after installing all silencers.Dynamic insertion loss for a dissipative silencer with 100 cm length was predicted to be 27.9 dB,which was in agreement with experimental ones.Although,there was no significant differences between insertion loss of silencers,the one with 30%porosity and 120 Kg/m^(3)rock wool density had the highest insertion loss of 26.2 dBA.Dissipative silencers noticeably reduced centrifugal fan noise exposures.Increasing sound absorbent density and duct porosity up to a certain limit could probably be effective in noise reduction of dissipative silencers.展开更多
In vitro maturation(IVM)is considered a potential assisted reproductive technology that is a safer and simpler alternative to conventional in vitro fertilization.It is primarily used in patients with impaired oocyte m...In vitro maturation(IVM)is considered a potential assisted reproductive technology that is a safer and simpler alternative to conventional in vitro fertilization.It is primarily used in patients with impaired oocyte maturation and for the treatment of infertile women who are at risk of fertility loss.In addition,IVM is currently used mainly in polycystic ovarian syndrome patients with a high ovarian response and is stll considered an experimental option in fertility preservation.Producing highly competent oocytes during IVM is considered a key step in the success of in vitro production(IVP)of embryos.Some factors,such as culture medium conditions and other supplements,have a significant impact on oocyte IVM performance.One of the known disruptors of oocyte developmental competence in IVP is oxidative stress(Os),which is caused by an imbalance between the production and neutralization of reactive oxygen species(ROS).In vitro conditions induce supraphysiological ROS levels due to exposure to an oxidative environment and the isolation of the oocyte from the follicle protective antioxidant milieu.Given the importance of Os in oocyte competence,the establishment of standardized antioxidant IVM systems is critical for improving the overall success of IVP.This review focuses on the main antioxidants tested to protect oocytes against OS in IVM.展开更多
基金the framework of a faculty research project under the code of Ethics Committee of IR.QUMS.REC.1396.163.We also thank Mehrdad Keshavarz Siahposh and Mohammad Soleiman Abady for their technical assistance in all our experimental work.
文摘Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal fan.Design charts were applied to predict noise reduction and length of a dissipative silencer.Dissipative silencers with various punched duct porosity(14%,30%and 40%)and sound absorbent density(80 Kg/m^(3),120 Kg/m^(3),and 140 Kg/m^(3))were designed and fabricated.According to ISO9612 and ISO11820,noise level was measured before and after installing all nine test silencers at fixed workstations around the discharge side of a centrifugal fan in a manufacturing plant.On average,the noise level at the discharge side of a fan without silencer was measured to be 93.6 dBA,whereas it was significantly mitigated by 67.4 dBA to 70.1 dBA after installing all silencers.Dynamic insertion loss for a dissipative silencer with 100 cm length was predicted to be 27.9 dB,which was in agreement with experimental ones.Although,there was no significant differences between insertion loss of silencers,the one with 30%porosity and 120 Kg/m^(3)rock wool density had the highest insertion loss of 26.2 dBA.Dissipative silencers noticeably reduced centrifugal fan noise exposures.Increasing sound absorbent density and duct porosity up to a certain limit could probably be effective in noise reduction of dissipative silencers.
基金financially supported by the Abadan University of Medical Sciences,Abadan,Iran(1401U-1467).
文摘In vitro maturation(IVM)is considered a potential assisted reproductive technology that is a safer and simpler alternative to conventional in vitro fertilization.It is primarily used in patients with impaired oocyte maturation and for the treatment of infertile women who are at risk of fertility loss.In addition,IVM is currently used mainly in polycystic ovarian syndrome patients with a high ovarian response and is stll considered an experimental option in fertility preservation.Producing highly competent oocytes during IVM is considered a key step in the success of in vitro production(IVP)of embryos.Some factors,such as culture medium conditions and other supplements,have a significant impact on oocyte IVM performance.One of the known disruptors of oocyte developmental competence in IVP is oxidative stress(Os),which is caused by an imbalance between the production and neutralization of reactive oxygen species(ROS).In vitro conditions induce supraphysiological ROS levels due to exposure to an oxidative environment and the isolation of the oocyte from the follicle protective antioxidant milieu.Given the importance of Os in oocyte competence,the establishment of standardized antioxidant IVM systems is critical for improving the overall success of IVP.This review focuses on the main antioxidants tested to protect oocytes against OS in IVM.
