A major problem facing the magnesium melting process is to address the oxidative combustion of magnesium.At present,there are still some problems in the method used to protect magnesium smelting.For example,the reacti...A major problem facing the magnesium melting process is to address the oxidative combustion of magnesium.At present,there are still some problems in the method used to protect magnesium smelting.For example,the reaction of covering flux with magnesium melt is likely to produce a large number of toxic and harmful gasses(Cl_(2) and HCl),the cost of such reaction is high,and there is a lack of clarity on the protection mechanism of CO_(2) acting as the protective gas of magnesium melt.Therefore,a new process is proposed in this paper to isolate the air on the surface of magnesium melt using MgO-C-Mg film.Based on the thermodynamic theory of MgO-C-Mg film formation during crude magnesium smelting,an investigation is conducted into the effect of different experimental conditions on the protective effect of magnesium.Not only is the protective mechanism of MgO-C-Mg film revealed,it is also verified that the MgO-C-Mg film can produce a more pronounced protective effect at suitable temperature.According to thermodynamic analysis,magnesium melt reacts with CO_(2) to form magnesium oxide and C.CO_(2) consumes C when the experimental temperature exceeds 700℃.This is contrary to the purpose of the experiment as it should be maintained at about 700℃.The experimental results show that an obvious protective effect can be produced on the magnesium melt by the MgO-C-Mg film generated under the following conditions of 90%CO_(2)-10%Ar,smelting temperature of 700℃,holding time of 60 min,and stirring time of 20 min.展开更多
The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hyperso...The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.展开更多
The protective behavior for a molten AZ91D alloy in an open melting furnace was investigated under a protective gas mixture containing 3% SO2 and 97% CO2, and the protection mechanism was discussed. Experimental resul...The protective behavior for a molten AZ91D alloy in an open melting furnace was investigated under a protective gas mixture containing 3% SO2 and 97% CO2, and the protection mechanism was discussed. Experimental results show that the gas mixture provides effective protection for AZ91D melt in the temperature range from 680 ℃ to 730 ℃. The microstructure, chemical composition and phase composition of the surface film formed on the molten AZ91D alloy were analyzed using scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS） and X-ray diffraction （XRD）. The SEM results demonstrate that the surface films with an average thickness between 0.5 pm and 2 pm are dense and coherent in the protected temperature range. The EDS results reveal that the surface film mainly contains elements S, C, O, AI and Mg. The XRD results show that the surface film consists of MgO, MgS and a small amount of C phase.展开更多
Sexually transmitted infections (STIs) and unwanted pregnancy (UP) are becoming a problem that affects significantly the younger segment of the population so, not only in the aspect of health, but in the development o...Sexually transmitted infections (STIs) and unwanted pregnancy (UP) are becoming a problem that affects significantly the younger segment of the population so, not only in the aspect of health, but in the development of its future life both emotional and school and work. Despite easy access to information, young people still have risky sexual practices. This research highlights protective practices with the aim of developing information and training tools that help them avoid risky behaviors that lead to dangerous situations in health and its future. It was a descriptive study with students who have recently entered of the Faculty of Medicine enrolled in school cycle in 2015 in the bachelor’s degree in Medicine and surgery, Nutrition and dietetics, and Rehabilitation programs who agreed to participate by letter of informed consent to respond to the Instrument for the Evaluation of Psychological Variables and Sexual Risk Behaviors. There were 221 participants, 166 in Medicine and surgery, 28 in Nutrition and dietetics, and 27 in Rehabilitation with an average of 18.6 years, 51% male and 49% female. A protective behavior was not having had sex with penetration (72.3%), due to wanting to have them with whom they are in love and to avoid STIs more frequently in female;another protective behavior was not having had oral sex with occasional partners or unprotected sex workers (15.4%);the reasons were to have wanted to use and that the couple asked him to use it, to avoid sexually transmitted infections because the couple’s sexual history is unknown. Regarding the likelihood of having sexual penetration (SP), participants who have not had it were found that: the men had less possibility to inquire about their partner’s sexual history, to reject the proposal to have SP and to refuse caresses in sensitive areas of the woman’s body;when asked about the likelihood of asking your partner to use a condom in their sexual relations, both men and women agreed that it would be quite likely that they would do so, more frequently in women. It concludes by emphasizing that prevention remains the cheapest, easiest, most reliable and safest tool against STIs and UP.展开更多
The physical protection system of the body consists of the protective organs for vulnerable body parts-functions and the protective countermeasures against invaders (pathogens), but to survive, the body also requires ...The physical protection system of the body consists of the protective organs for vulnerable body parts-functions and the protective countermeasures against invaders (pathogens), but to survive, the body also requires the protective social groups for vulnerable social members-functions and the protective instinctive mental countermeasures against adversities such as hardship, danger, and unfamiliarity-uncertainty. As a result, this paper proposes that the mental protection system of the body consists of the social brain to set up the protective social groups for vulnerable social members-functions and the mental immune system to produce the protective mental countermeasures against adversities. This paper proposes that from the social brain, the protective social groups include alliance group for vulnerable individuals, kinship-friendship group for vulnerable children, interdependent specialists group for vulnerable pregnant females, territorial group for social boundary, connective group for social connection, and competitive group for social competition. From the mental immune system, the mental protective countermeasures include comforter against hardship, hyperactivity against danger, phobia against unfamiliarity-uncertainty, and rationality against unfamiliarity-uncertainty. The overactive mental immune system causes mental allergies and auto immune diseases as personality-mental disorders against ubiquitous harmful and harmless perceived adversities, correlating to physical allergies and auto immune diseases against ubiquitous harmful and harmless detected invaders. The mental protection system also produces personality traits, social moralities, social organizations, social systems, religions, and cultures as described in this paper. The mental protective system is the source of protective behaviors.展开更多
基金supported by the Yunnan Province Nonferrous Metal Vacuum Metallurgy Top Team[grant number 202305AS350012].
文摘A major problem facing the magnesium melting process is to address the oxidative combustion of magnesium.At present,there are still some problems in the method used to protect magnesium smelting.For example,the reaction of covering flux with magnesium melt is likely to produce a large number of toxic and harmful gasses(Cl_(2) and HCl),the cost of such reaction is high,and there is a lack of clarity on the protection mechanism of CO_(2) acting as the protective gas of magnesium melt.Therefore,a new process is proposed in this paper to isolate the air on the surface of magnesium melt using MgO-C-Mg film.Based on the thermodynamic theory of MgO-C-Mg film formation during crude magnesium smelting,an investigation is conducted into the effect of different experimental conditions on the protective effect of magnesium.Not only is the protective mechanism of MgO-C-Mg film revealed,it is also verified that the MgO-C-Mg film can produce a more pronounced protective effect at suitable temperature.According to thermodynamic analysis,magnesium melt reacts with CO_(2) to form magnesium oxide and C.CO_(2) consumes C when the experimental temperature exceeds 700℃.This is contrary to the purpose of the experiment as it should be maintained at about 700℃.The experimental results show that an obvious protective effect can be produced on the magnesium melt by the MgO-C-Mg film generated under the following conditions of 90%CO_(2)-10%Ar,smelting temperature of 700℃,holding time of 60 min,and stirring time of 20 min.
基金support from the Natural Science Foundation of China(91016029,91216302,and 91216301)
文摘The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.
基金supported by the Ministry of Science and Technology Project of China(2009, No. GJB20011)
文摘The protective behavior for a molten AZ91D alloy in an open melting furnace was investigated under a protective gas mixture containing 3% SO2 and 97% CO2, and the protection mechanism was discussed. Experimental results show that the gas mixture provides effective protection for AZ91D melt in the temperature range from 680 ℃ to 730 ℃. The microstructure, chemical composition and phase composition of the surface film formed on the molten AZ91D alloy were analyzed using scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS） and X-ray diffraction （XRD）. The SEM results demonstrate that the surface films with an average thickness between 0.5 pm and 2 pm are dense and coherent in the protected temperature range. The EDS results reveal that the surface film mainly contains elements S, C, O, AI and Mg. The XRD results show that the surface film consists of MgO, MgS and a small amount of C phase.
文摘Sexually transmitted infections (STIs) and unwanted pregnancy (UP) are becoming a problem that affects significantly the younger segment of the population so, not only in the aspect of health, but in the development of its future life both emotional and school and work. Despite easy access to information, young people still have risky sexual practices. This research highlights protective practices with the aim of developing information and training tools that help them avoid risky behaviors that lead to dangerous situations in health and its future. It was a descriptive study with students who have recently entered of the Faculty of Medicine enrolled in school cycle in 2015 in the bachelor’s degree in Medicine and surgery, Nutrition and dietetics, and Rehabilitation programs who agreed to participate by letter of informed consent to respond to the Instrument for the Evaluation of Psychological Variables and Sexual Risk Behaviors. There were 221 participants, 166 in Medicine and surgery, 28 in Nutrition and dietetics, and 27 in Rehabilitation with an average of 18.6 years, 51% male and 49% female. A protective behavior was not having had sex with penetration (72.3%), due to wanting to have them with whom they are in love and to avoid STIs more frequently in female;another protective behavior was not having had oral sex with occasional partners or unprotected sex workers (15.4%);the reasons were to have wanted to use and that the couple asked him to use it, to avoid sexually transmitted infections because the couple’s sexual history is unknown. Regarding the likelihood of having sexual penetration (SP), participants who have not had it were found that: the men had less possibility to inquire about their partner’s sexual history, to reject the proposal to have SP and to refuse caresses in sensitive areas of the woman’s body;when asked about the likelihood of asking your partner to use a condom in their sexual relations, both men and women agreed that it would be quite likely that they would do so, more frequently in women. It concludes by emphasizing that prevention remains the cheapest, easiest, most reliable and safest tool against STIs and UP.
文摘The physical protection system of the body consists of the protective organs for vulnerable body parts-functions and the protective countermeasures against invaders (pathogens), but to survive, the body also requires the protective social groups for vulnerable social members-functions and the protective instinctive mental countermeasures against adversities such as hardship, danger, and unfamiliarity-uncertainty. As a result, this paper proposes that the mental protection system of the body consists of the social brain to set up the protective social groups for vulnerable social members-functions and the mental immune system to produce the protective mental countermeasures against adversities. This paper proposes that from the social brain, the protective social groups include alliance group for vulnerable individuals, kinship-friendship group for vulnerable children, interdependent specialists group for vulnerable pregnant females, territorial group for social boundary, connective group for social connection, and competitive group for social competition. From the mental immune system, the mental protective countermeasures include comforter against hardship, hyperactivity against danger, phobia against unfamiliarity-uncertainty, and rationality against unfamiliarity-uncertainty. The overactive mental immune system causes mental allergies and auto immune diseases as personality-mental disorders against ubiquitous harmful and harmless perceived adversities, correlating to physical allergies and auto immune diseases against ubiquitous harmful and harmless detected invaders. The mental protection system also produces personality traits, social moralities, social organizations, social systems, religions, and cultures as described in this paper. The mental protective system is the source of protective behaviors.
