Potentiodynamic electrochemical technique was utilized to study the corrosion behavior of magnesium alloys in simulated body fluids(SBFs). The influence of materials,solutions and their temperature on corrosion rate w...Potentiodynamic electrochemical technique was utilized to study the corrosion behavior of magnesium alloys in simulated body fluids(SBFs). The influence of materials,solutions and their temperature on corrosion rate was mainly discussed. The results demonstrate that the free corrosion potential(Ecorr) of AZ31 and AZ91 alloys rises rapidly at initial stage,and then stabilizes at some value. Ecorr of WE43 alloy increases continuously. While Ecorr of AZ91 alloy with macro-arc oxidation(MAO) coating decreases drastically in 3 min,and then fluctuates between -1 607 mV and -1 503 mV. The WE43 alloy has better corrosion resistance in Hank's solution,compared with AZ31 and AZ91 alloys. Corrosion rates of the alloys are sensitive to the chemical composition and temperature of SBFs. A thin MgF2 film slightly improves corrosion resistance. An MAO coating on AZ91 alloy significantly reduces corrosion rate and enhances Ecorr. Pitting corrosion occurs on both AZ31 and WE43 alloys in Hank's solution.展开更多
Thermal drying could lead to the deterioration of substance which affect its nutraceutical and chemical properties. Hence, thermal stability of substance is necessary in course of its drying to acertain the degree of ...Thermal drying could lead to the deterioration of substance which affect its nutraceutical and chemical properties. Hence, thermal stability of substance is necessary in course of its drying to acertain the degree of temperature it will be subjected to. In this research, sclerotium of Pleurotus tuberregium is subjected to thermogravimetric analysis, differential thermal analysis and differential scanning calorimetry. Both thermogravimetric analysis and differential thermal analysis were conducted from ambient temperature to 1000°C at a rate of 20°C/min constant heating rate, while differential scanning calorimetry was conducted from ambient temperature to 400°C at a rate of 10°C/min constant heating rate. Besides, the oxides contents of sclerotium of Pleurotus tuberregium were determined using x-ray fluorescence analysis and the mircostruture was determined with scanning electron microscopy. It was discovered that complete dehydration of the sample ended at about 110.38°C and oxidation reaction occurred between 233.42°C to 373.82°C with release of heat by the sample. Sclerotium of Pleurotus tuber-regium is thermal stable up to 233.42°C with decompostion of steroid which is its second major component at about 400°C to 480°C. The x-ray fluorescence analysis of sclerotium of Pleurotus tuber-regium revealed that Na<sub>2</sub>O, MgO, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, and Fe<sub>2</sub>O<sub>3</sub> are the major compound and SEM analysis showed that it is a solid with amorphous structure having some fibrous skeleton. This study revealed that sclerotium of Pleurotus tuberregium could be dried to minimal moisture content without the deterioration of its nutritional and medinicnal properties.展开更多
基金Project (8655) supported by the Natural Science Foundation of Chongqing Municipal Science and Technology Commission, ChinaProject(50405005) supported by the National Science Foundation of China
文摘Potentiodynamic electrochemical technique was utilized to study the corrosion behavior of magnesium alloys in simulated body fluids(SBFs). The influence of materials,solutions and their temperature on corrosion rate was mainly discussed. The results demonstrate that the free corrosion potential(Ecorr) of AZ31 and AZ91 alloys rises rapidly at initial stage,and then stabilizes at some value. Ecorr of WE43 alloy increases continuously. While Ecorr of AZ91 alloy with macro-arc oxidation(MAO) coating decreases drastically in 3 min,and then fluctuates between -1 607 mV and -1 503 mV. The WE43 alloy has better corrosion resistance in Hank's solution,compared with AZ31 and AZ91 alloys. Corrosion rates of the alloys are sensitive to the chemical composition and temperature of SBFs. A thin MgF2 film slightly improves corrosion resistance. An MAO coating on AZ91 alloy significantly reduces corrosion rate and enhances Ecorr. Pitting corrosion occurs on both AZ31 and WE43 alloys in Hank's solution.
基金Supported by the National Natural Science Foundation of China （No. 10174057 90201011）, the Technology Import Item of Ministry of Education （No. 105148）, the Application Foundation of Sichuan Province （No. 03JY029-048-1 ） and the Science Study Foundation of Southwest Jiaotong University （No. 2001B11）.
文摘Thermal drying could lead to the deterioration of substance which affect its nutraceutical and chemical properties. Hence, thermal stability of substance is necessary in course of its drying to acertain the degree of temperature it will be subjected to. In this research, sclerotium of Pleurotus tuberregium is subjected to thermogravimetric analysis, differential thermal analysis and differential scanning calorimetry. Both thermogravimetric analysis and differential thermal analysis were conducted from ambient temperature to 1000°C at a rate of 20°C/min constant heating rate, while differential scanning calorimetry was conducted from ambient temperature to 400°C at a rate of 10°C/min constant heating rate. Besides, the oxides contents of sclerotium of Pleurotus tuberregium were determined using x-ray fluorescence analysis and the mircostruture was determined with scanning electron microscopy. It was discovered that complete dehydration of the sample ended at about 110.38°C and oxidation reaction occurred between 233.42°C to 373.82°C with release of heat by the sample. Sclerotium of Pleurotus tuber-regium is thermal stable up to 233.42°C with decompostion of steroid which is its second major component at about 400°C to 480°C. The x-ray fluorescence analysis of sclerotium of Pleurotus tuber-regium revealed that Na<sub>2</sub>O, MgO, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, and Fe<sub>2</sub>O<sub>3</sub> are the major compound and SEM analysis showed that it is a solid with amorphous structure having some fibrous skeleton. This study revealed that sclerotium of Pleurotus tuberregium could be dried to minimal moisture content without the deterioration of its nutritional and medinicnal properties.
