The Mg-6Al-4Zn alloy was fabricated by mechanical alloying(MA)and hot pressing to serve as biodegradable metal implant.The influence of addition of 1%Si(mass fraction)on the microstructure,mechanical properties and bi...The Mg-6Al-4Zn alloy was fabricated by mechanical alloying(MA)and hot pressing to serve as biodegradable metal implant.The influence of addition of 1%Si(mass fraction)on the microstructure,mechanical properties and bio-corrosion behavior of Mg-6Al-1Zn alloy was studied using X-ray diffractometry,transmission electron microscopy,compression test,as well as immersion,electrochemical test and MTT assay.The results showed that the addition of 1%Si to Mg-6Al-1Zn alloy led to the formation of fine Mg2Si phase with polygonal shape,and increased compressive strength,elongation and improved corrosion resistance.Furthermore,the cell viability of Saos-2 cells has been improved by addition of 1%Si to Mg-6Al-1Zn alloy.According to the results,the magnesium ions released in the methylthiazol tetrazolium(MTT)test have not shown any cell toxicity.All these indicated that the addition of 1%Si improved the properties of Mg-6Al-4Zn alloy for using as a biodegradable implant.展开更多
Identification and development of sustainable land management is urgently required because of widespread resource degradation from poor land use practices.In addition,the world will need to increase food production to...Identification and development of sustainable land management is urgently required because of widespread resource degradation from poor land use practices.In addition,the world will need to increase food production to meet the nutritional needs of a growing global population without major environmental degradation.Ongoing climate change and its impacts on the environment is an additional factor to consider in identifying and developing sustainable land use practices.The objectives of this paper are to:(1)provide a background to the need for sustainable land management,(2)identify some of its major components,and(3)discuss some examples of sustainable land management systems that are being practiced around the world.Some common components of this type of management are:(1)understanding the ecology of land management,(2)maintenance or enhancement of land productivity,(3)maintenance of soil quality,(4)increased diversity for higher stability and resilience,(5)provision of economic and ecosystem service benefits for communities,and(6)social acceptability.Several examples of sustainable land management systems are discussed to illustrate the wide range of systems that have been developed around the world including agroforestry,conservation agriculture,and precision agricultural systems.Improved technology,allowing for geater environmental measurement and for improved access and sharing of information,provides opportunities to identify and develop more sustainable land management practices and systems for the future.展开更多
Objective:To compare the seropositivity of Toxoplasma gondii in a group of peritoneal dialysis patients with hemodialysis patients and a general local population as a control group in Tabriz,Northwest Iran.Methods:A t...Objective:To compare the seropositivity of Toxoplasma gondii in a group of peritoneal dialysis patients with hemodialysis patients and a general local population as a control group in Tabriz,Northwest Iran.Methods:A total of 176 individuals were participated in the present study.Among them,42 were peritoneal dialysis patients,84 were hemodialysis patients and 50 were healthy volunteers.Anti-Toxoplasma immunoglobulin G and immunoglobulin M serologic study was administered on the collected serums and then the obtained data were analyzed using statistical methods.Results:In the present research,70.2%of hemodialysis patients,66.6%of peritoneal dialysis patients and 68%of control group had positive results for anti-Toxoplasma immunoglobulin G antibody.All individuals of the groups had negative serologic results for anti-Toxoplasma immunoglobulin M antibody.There was no significant difference between Toxoplasma gondii seropositivity in hemodialysis patients and peritoneal dialysis patients and general population(P>0.05).Conclusions:The findings showed that either peritoneal dialysis or hemodialysis doesn’t increase the risk of Toxoplasma seropositivity in our region(Northwest Iran).It could be explained by the fact that the present research is carried out in a high seroprevalent area scale in which the majority of normal population had previous exposure to this parasitical infection.展开更多
Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this wo...Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this work. Calculations were performed using the ORNL （Oak Ridge national laboratory） human phantom and Monte Carlo N-particle transport code MCNP-4C according to ICRPI03 recommendations. Optimum dimensions of each source were determined considering the incident photon energy. Then, these dimensions were employed in the MCNP code input for calculation of conversion factors which relate the effective dose rate and activity. The obtained factors of the 238U series, 232Th series and the 4~K in soil are 0.383, 0.314 and 0.019 nSv h-~ per Bq kg~, respectively. These results were compared with other studies and revealed that there is a good agreement exists between two sets of data. The estimation of the effective dose rates and the annual effective dose for the adult population has been derived in different regions of Iran, considering the natural radioactivity distribution in soil samples from these regions. Finally, the obtained results in this study were compared with UNSCEAR （United Nations Scientific Committee on the Effects of Atomic Radiation） 2008 report.展开更多
Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not bee...Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration.展开更多
文摘The Mg-6Al-4Zn alloy was fabricated by mechanical alloying(MA)and hot pressing to serve as biodegradable metal implant.The influence of addition of 1%Si(mass fraction)on the microstructure,mechanical properties and bio-corrosion behavior of Mg-6Al-1Zn alloy was studied using X-ray diffractometry,transmission electron microscopy,compression test,as well as immersion,electrochemical test and MTT assay.The results showed that the addition of 1%Si to Mg-6Al-1Zn alloy led to the formation of fine Mg2Si phase with polygonal shape,and increased compressive strength,elongation and improved corrosion resistance.Furthermore,the cell viability of Saos-2 cells has been improved by addition of 1%Si to Mg-6Al-1Zn alloy.According to the results,the magnesium ions released in the methylthiazol tetrazolium(MTT)test have not shown any cell toxicity.All these indicated that the addition of 1%Si improved the properties of Mg-6Al-4Zn alloy for using as a biodegradable implant.
文摘Identification and development of sustainable land management is urgently required because of widespread resource degradation from poor land use practices.In addition,the world will need to increase food production to meet the nutritional needs of a growing global population without major environmental degradation.Ongoing climate change and its impacts on the environment is an additional factor to consider in identifying and developing sustainable land use practices.The objectives of this paper are to:(1)provide a background to the need for sustainable land management,(2)identify some of its major components,and(3)discuss some examples of sustainable land management systems that are being practiced around the world.Some common components of this type of management are:(1)understanding the ecology of land management,(2)maintenance or enhancement of land productivity,(3)maintenance of soil quality,(4)increased diversity for higher stability and resilience,(5)provision of economic and ecosystem service benefits for communities,and(6)social acceptability.Several examples of sustainable land management systems are discussed to illustrate the wide range of systems that have been developed around the world including agroforestry,conservation agriculture,and precision agricultural systems.Improved technology,allowing for geater environmental measurement and for improved access and sharing of information,provides opportunities to identify and develop more sustainable land management practices and systems for the future.
基金Supported by Student’s Research Committee of Tabriz University of Medical Sciences(Project No.92-11-45).
文摘Objective:To compare the seropositivity of Toxoplasma gondii in a group of peritoneal dialysis patients with hemodialysis patients and a general local population as a control group in Tabriz,Northwest Iran.Methods:A total of 176 individuals were participated in the present study.Among them,42 were peritoneal dialysis patients,84 were hemodialysis patients and 50 were healthy volunteers.Anti-Toxoplasma immunoglobulin G and immunoglobulin M serologic study was administered on the collected serums and then the obtained data were analyzed using statistical methods.Results:In the present research,70.2%of hemodialysis patients,66.6%of peritoneal dialysis patients and 68%of control group had positive results for anti-Toxoplasma immunoglobulin G antibody.All individuals of the groups had negative serologic results for anti-Toxoplasma immunoglobulin M antibody.There was no significant difference between Toxoplasma gondii seropositivity in hemodialysis patients and peritoneal dialysis patients and general population(P>0.05).Conclusions:The findings showed that either peritoneal dialysis or hemodialysis doesn’t increase the risk of Toxoplasma seropositivity in our region(Northwest Iran).It could be explained by the fact that the present research is carried out in a high seroprevalent area scale in which the majority of normal population had previous exposure to this parasitical infection.
文摘Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this work. Calculations were performed using the ORNL （Oak Ridge national laboratory） human phantom and Monte Carlo N-particle transport code MCNP-4C according to ICRPI03 recommendations. Optimum dimensions of each source were determined considering the incident photon energy. Then, these dimensions were employed in the MCNP code input for calculation of conversion factors which relate the effective dose rate and activity. The obtained factors of the 238U series, 232Th series and the 4~K in soil are 0.383, 0.314 and 0.019 nSv h-~ per Bq kg~, respectively. These results were compared with other studies and revealed that there is a good agreement exists between two sets of data. The estimation of the effective dose rates and the annual effective dose for the adult population has been derived in different regions of Iran, considering the natural radioactivity distribution in soil samples from these regions. Finally, the obtained results in this study were compared with UNSCEAR （United Nations Scientific Committee on the Effects of Atomic Radiation） 2008 report.
文摘Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration.
