Lunar habitat construction is crucial for successful lunar exploration missions.Due to the limitations of transportation conditions,extensive global research has been conducted on lunar in situ material processing tec...Lunar habitat construction is crucial for successful lunar exploration missions.Due to the limitations of transportation conditions,extensive global research has been conducted on lunar in situ material processing techniques in recent years.The aim of this paper is to provide a comprehensive review,precise classification,and quantitative evaluation of these approaches,focusing specifically on four main approaches:reaction solidification(RS),sintering/melting(SM),bonding solidification(BS),and confinement formation(CF).Eight key indicators have been identified for the construction of low-cost and highperformance systems to assess the feasibility of these methods:in situ material ratio,curing temperature,curing time,implementation conditions,compressive strength,tensile strength,curing dimensions,and environmental adaptability.The scoring thresholds are determined by comparing the construction requirements with the actual capabilities.Among the evaluated methods,regolith bagging has emerged as a promising option due to its high in situ material ratio,low time requirement,lack of hightemperature requirements,and minimal shortcomings,with only the compressive strength falling below the neutral score.The compressive strength still maintains a value of 2–3 MPa.The proposed construction scheme utilizing regolith bags offers numerous advantages,including rapid and large-scale construction,ensured tensile strength,and reduced reliance on equipment and energy.In this study,guidelines for evaluating regolith solidification techniques are provided,and directions for improvement are offered.The proposed lunar habitat design based on regolith bags is a practical reference for future research.展开更多
Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. Ho...Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. However, the outcome of.this technique might be affected by many factors such as sequence of nylon bags incubation in the rumen. The objective of current study was to investigate effects of sequence of nylon bag incubation on degradative behavior of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in some feed ingredients commonly used in dairy rations, including alfalfa haylage, corn silage, corn grain and soybean meal. Four multiparous Holstein lactating cows fitted with permanent ruminal cannulas were used. The nylon bags containing feed samples either were placed in the rumen at once and removed at designated time intervals (all in-gradually out method; AG) or were placed in the rumen at designated time points and retrieved at once (gradually in-all out method; GA). Fractional rate of degradation of potentially degradable fraction, lag time and effective rumen degradability (ED) of DM and CP were significantly higher in the AG compared to the GA method (P〈0.05). Fractional rates of DM and CP degradation was higher in alfalfa haylage samples incubated in the rumen using the AG method compared to that using the GA method (0.138 h-1 vs. 0.073 h-1 and 0.002 h-1 vs. 0.1125 h-1, for DM and CP, respectively; P〈0.05). Due to a higher fractional rate of degradation (Kd) of DM and CP, the ED of DM and CP at different fractional passage rates were higher in the AG than those in the GA method (P〈0.05). Potentially degradable fraction and lag time of NDF were higher in the AG method compared to the GA method (P〈0.05). Placing all bags in the rumen at once and removing them at designated time intervals compared with introduction of bags in reverse sequence and removing them all at once led to a lower undegradable fraction (U) of NDF in alfalfa (1.8% vs. 4.0%, respectively; P〈0.05) and corn silage (3.3% vs. 6.7%, respectively; P〈0.05) samples. Potentially degradable fraction of ADF was significantly higher in the AG method compared with the GA method (P〈0.05). Bag incubation sequence had profound effects on kinetics of degradation of DM, CP and NDF in situ in the feed samples studied. The effects were more evident in the forages (especially alfalfa haylage) than in the concentrate ingredientsnamely corn grain and soybean meal..This experiment is the first time to investigate effects of two methods under the same experiment conditions, providing basic data for the determination of ED.展开更多
Two highly cross-linked superfine styrene-butadiene rubber particles, one with 1 wt% of carboxyl groups and theother without such groups having particle sizes of 130-150 nm and 80-100 nm respectively, were used to pre...Two highly cross-linked superfine styrene-butadiene rubber particles, one with 1 wt% of carboxyl groups and theother without such groups having particle sizes of 130-150 nm and 80-100 nm respectively, were used to prepare nylon6/rubber composites via in situ polymerization. It was found that carboxylic styrene-butadiene dispersed uniformly in nylonmatrix and there was strong interfacial interaction because of the graft polymer formed by the reaction of nylon with carboxylgroup of the rubber, resulting in considerably improved impact strength with almost unchanged tensile strength. However,the addition of styrene-butadiene without carboxyl groups showed intensive agglomeration of the rubber particles and weakinterfacial interactions, and the toughness of the materials was improved slightly. The crystallization and rheological behavior of the composites were also discussed.展开更多
尼龙6(PA6)树脂具有优异的性能,其连续纤维复合材料在汽车、航空航天领域具有广泛应用。但是PA6树脂熔融后黏度较高,不易对连续纤维充分浸渍,并且连续纤维与PA6的复合材料界面黏附性较差,限制了其复合材料的性能和应用。针对这些问题,...尼龙6(PA6)树脂具有优异的性能,其连续纤维复合材料在汽车、航空航天领域具有广泛应用。但是PA6树脂熔融后黏度较高,不易对连续纤维充分浸渍,并且连续纤维与PA6的复合材料界面黏附性较差,限制了其复合材料的性能和应用。针对这些问题,文中对连续玻璃纤维增强尼龙6(CGF/PA6)复合材料开展了研究。首先,采用阴离子开环聚合制备PA6,确定了其最佳制备工艺;其次,用硅烷偶联剂KH550(AP)对连续玻璃纤维(CGF)进行改性,并对其进行了红外光谱表征;最后,通过原位聚合法制备了CGF/PA6复合材料,研究了AP改性对CGF/PA6复合材料力学性能的影响,并对CGF/PA6复合材料的拉伸断口进行了扫描电镜分析。结果表明,AP被键合到了CGF表面,AP改性可以增强CGF/PA6复合材料的界面黏附性,从而使CGF/PA6复合材料的拉伸强度得到改善,当AP用量为2%时,CGF/PA6复合材料的拉伸强度高达88.52 MPa,此时,复合材料的断裂伸长率最低,为4.90%。CGF/PA6复合材料的冲击强度变化不大,均在50 k J/m2左右,说明复合材料的韧性受CGF表面改性影响较小。展开更多
A series of La2O3/MC nylon nanocomposites were prepared via in situ polymerization. The effects of content of nano-La2O3 on the mechanical properties of nanocomposites were studied. Dispersion of nano-La2O3 in MC nylo...A series of La2O3/MC nylon nanocomposites were prepared via in situ polymerization. The effects of content of nano-La2O3 on the mechanical properties of nanocomposites were studied. Dispersion of nano-La2O3 in MC nylon matrix was observed with SEM. The crystal structure of nanocomposites was characterized by means of XRD. SEM analysis shows that La2O3 nanoparticles are uniformly dispersed in MC nylon matrix and little clustering exists when the content of nano- La2O3 is lower than 1%, however, when the content of nano-La2O3 is more than 1%, it begins to cluster. XRD analysis indicats that nano-La2O3 does not change the crystal structure of MC nylon. Mechanical properties tests show that the tensile strength, elongation at break, impact strength, flexural strength, and flexural modulus of nanocomposites first increase then decrease as the content of nano-La2O3 is increased. When the content of nano-La2O3 is 0.5%, the tensile strength and elongation at break of nanocomposites reach maximum, which are 17.9% and 52.1% higher respectively than those of MC nylon. When the content of nano-La2O3 is 1.0%, the impact strength, flexural strength and flexural modulus of nanocomposites reach maximum, which are 36.6 %, 12.7 % and 16.3 % higher respectively than those of MC nylon.展开更多
Alfalfa (Medicago sativa) is difficult to ensile successfully because of the low content of moisture and water-soluble carbohydrates (WSC) in fresh alfalfa and the high buffering capacity in fresh alfalfa. Here, w...Alfalfa (Medicago sativa) is difficult to ensile successfully because of the low content of moisture and water-soluble carbohydrates (WSC) in fresh alfalfa and the high buffering capacity in fresh alfalfa. Here, we conducted a study to evaluate the effects of three lactic acid bacteria (LAB) inoculants (Lactobacillus case/, lactobacillus plantarum, and Pediococcus pentosaceus) on silage quality, in sitE/ruminal degradability, and in vitro fermentation of alfalfa silage. The first cut of alfalfa was wilted, chopped, and randomly divided into four groups: the control (CON) and control mixed with three separate LAB inoculants (106 cfu g-1). Simmental steers with a body weight of (452±18) kg and with installed rumen fistulas were prepared for in situ degradation and for in vitro gas production. LAB inoculants had a lower (P〈0.05) content of butyric acid than the CON group. Among them, the L. casei inoculated silage had a higher (P〈0.05) content of water-soluble carbohydrate (WSC) and a lower (P〈0.05) NH3-H content. The effective degradation (ED) of crude protein in LAB inoculation decreased (P〈0.05), while the ED of acid detergent fiber increased (P〈0.05) in situ fermentation. The alfalfa silage with LAB inoculants produced more carbon dioxide (P〈0.05). The NH3-H content of mixed incubation fluid in L. casei inoculated silage was lower (P〈0.05) compared with other groups. Therefore, this study showed that LAB inoculants could improve both ensiling quality and degradation. In particular, the L. casei inoculations exhibited better performance by limiting proteolysis during ensiling.展开更多
This study was carried out to determine nutritive value of pomegranate pomace using in situ and gas production techniques. In this study, two fistulated wethers (38 ± 1.5 kg) were used in situ method. The gas p...This study was carried out to determine nutritive value of pomegranate pomace using in situ and gas production techniques. In this study, two fistulated wethers (38 ± 1.5 kg) were used in situ method. The gas production was measured at 2, 4, 6, 8, 12, 16, 24, 36 and 48 h and ruminal DM (dry matter) and CP (crude protein) disappearances were measured at 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h. DM degradabilities of treated pomegranate pomace at 8 h to 96 h were larger than untreated pomegranate pomacewhich showed significant differences (p 〈 0.05). CP degradabilities of treated pomegranate pomace at 96 h was 62.38% that showed significant differences (p 〈 0.05). The metabolizable proteins of treated and untreated pomegranate pomace were 73 and 64.27 g/kg respectively that showed significant differences (p 〈 0.05). The gas productions of treated and untreated pomegranate pomace at 48 h were 79.91 and 128.75 mL/g DM respectively that showed significant differences (p 〈 0.05). It was concluded that the pomegranate pomace can be used largely as ruminant feeds.展开更多
基金supported by the National Natural Science Foundation of China(42241109)the Guoqiang Institute,Tsinghua University(2021GQG1001)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Lunar habitat construction is crucial for successful lunar exploration missions.Due to the limitations of transportation conditions,extensive global research has been conducted on lunar in situ material processing techniques in recent years.The aim of this paper is to provide a comprehensive review,precise classification,and quantitative evaluation of these approaches,focusing specifically on four main approaches:reaction solidification(RS),sintering/melting(SM),bonding solidification(BS),and confinement formation(CF).Eight key indicators have been identified for the construction of low-cost and highperformance systems to assess the feasibility of these methods:in situ material ratio,curing temperature,curing time,implementation conditions,compressive strength,tensile strength,curing dimensions,and environmental adaptability.The scoring thresholds are determined by comparing the construction requirements with the actual capabilities.Among the evaluated methods,regolith bagging has emerged as a promising option due to its high in situ material ratio,low time requirement,lack of hightemperature requirements,and minimal shortcomings,with only the compressive strength falling below the neutral score.The compressive strength still maintains a value of 2–3 MPa.The proposed construction scheme utilizing regolith bags offers numerous advantages,including rapid and large-scale construction,ensured tensile strength,and reduced reliance on equipment and energy.In this study,guidelines for evaluating regolith solidification techniques are provided,and directions for improvement are offered.The proposed lunar habitat design based on regolith bags is a practical reference for future research.
基金the financial supports of the National Natural Science Foundation of China(30901030,31372334)the Key Technologies R&D Program of China(2012BAD12B02)the Program for Beijing Excellent Talents,China(2013D009007000003)
文摘Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. However, the outcome of.this technique might be affected by many factors such as sequence of nylon bags incubation in the rumen. The objective of current study was to investigate effects of sequence of nylon bag incubation on degradative behavior of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in some feed ingredients commonly used in dairy rations, including alfalfa haylage, corn silage, corn grain and soybean meal. Four multiparous Holstein lactating cows fitted with permanent ruminal cannulas were used. The nylon bags containing feed samples either were placed in the rumen at once and removed at designated time intervals (all in-gradually out method; AG) or were placed in the rumen at designated time points and retrieved at once (gradually in-all out method; GA). Fractional rate of degradation of potentially degradable fraction, lag time and effective rumen degradability (ED) of DM and CP were significantly higher in the AG compared to the GA method (P〈0.05). Fractional rates of DM and CP degradation was higher in alfalfa haylage samples incubated in the rumen using the AG method compared to that using the GA method (0.138 h-1 vs. 0.073 h-1 and 0.002 h-1 vs. 0.1125 h-1, for DM and CP, respectively; P〈0.05). Due to a higher fractional rate of degradation (Kd) of DM and CP, the ED of DM and CP at different fractional passage rates were higher in the AG than those in the GA method (P〈0.05). Potentially degradable fraction and lag time of NDF were higher in the AG method compared to the GA method (P〈0.05). Placing all bags in the rumen at once and removing them at designated time intervals compared with introduction of bags in reverse sequence and removing them all at once led to a lower undegradable fraction (U) of NDF in alfalfa (1.8% vs. 4.0%, respectively; P〈0.05) and corn silage (3.3% vs. 6.7%, respectively; P〈0.05) samples. Potentially degradable fraction of ADF was significantly higher in the AG method compared with the GA method (P〈0.05). Bag incubation sequence had profound effects on kinetics of degradation of DM, CP and NDF in situ in the feed samples studied. The effects were more evident in the forages (especially alfalfa haylage) than in the concentrate ingredientsnamely corn grain and soybean meal..This experiment is the first time to investigate effects of two methods under the same experiment conditions, providing basic data for the determination of ED.
文摘Two highly cross-linked superfine styrene-butadiene rubber particles, one with 1 wt% of carboxyl groups and theother without such groups having particle sizes of 130-150 nm and 80-100 nm respectively, were used to prepare nylon6/rubber composites via in situ polymerization. It was found that carboxylic styrene-butadiene dispersed uniformly in nylonmatrix and there was strong interfacial interaction because of the graft polymer formed by the reaction of nylon with carboxylgroup of the rubber, resulting in considerably improved impact strength with almost unchanged tensile strength. However,the addition of styrene-butadiene without carboxyl groups showed intensive agglomeration of the rubber particles and weakinterfacial interactions, and the toughness of the materials was improved slightly. The crystallization and rheological behavior of the composites were also discussed.
文摘尼龙6(PA6)树脂具有优异的性能,其连续纤维复合材料在汽车、航空航天领域具有广泛应用。但是PA6树脂熔融后黏度较高,不易对连续纤维充分浸渍,并且连续纤维与PA6的复合材料界面黏附性较差,限制了其复合材料的性能和应用。针对这些问题,文中对连续玻璃纤维增强尼龙6(CGF/PA6)复合材料开展了研究。首先,采用阴离子开环聚合制备PA6,确定了其最佳制备工艺;其次,用硅烷偶联剂KH550(AP)对连续玻璃纤维(CGF)进行改性,并对其进行了红外光谱表征;最后,通过原位聚合法制备了CGF/PA6复合材料,研究了AP改性对CGF/PA6复合材料力学性能的影响,并对CGF/PA6复合材料的拉伸断口进行了扫描电镜分析。结果表明,AP被键合到了CGF表面,AP改性可以增强CGF/PA6复合材料的界面黏附性,从而使CGF/PA6复合材料的拉伸强度得到改善,当AP用量为2%时,CGF/PA6复合材料的拉伸强度高达88.52 MPa,此时,复合材料的断裂伸长率最低,为4.90%。CGF/PA6复合材料的冲击强度变化不大,均在50 k J/m2左右,说明复合材料的韧性受CGF表面改性影响较小。
文摘A series of La2O3/MC nylon nanocomposites were prepared via in situ polymerization. The effects of content of nano-La2O3 on the mechanical properties of nanocomposites were studied. Dispersion of nano-La2O3 in MC nylon matrix was observed with SEM. The crystal structure of nanocomposites was characterized by means of XRD. SEM analysis shows that La2O3 nanoparticles are uniformly dispersed in MC nylon matrix and little clustering exists when the content of nano- La2O3 is lower than 1%, however, when the content of nano-La2O3 is more than 1%, it begins to cluster. XRD analysis indicats that nano-La2O3 does not change the crystal structure of MC nylon. Mechanical properties tests show that the tensile strength, elongation at break, impact strength, flexural strength, and flexural modulus of nanocomposites first increase then decrease as the content of nano-La2O3 is increased. When the content of nano-La2O3 is 0.5%, the tensile strength and elongation at break of nanocomposites reach maximum, which are 17.9% and 52.1% higher respectively than those of MC nylon. When the content of nano-La2O3 is 1.0%, the impact strength, flexural strength and flexural modulus of nanocomposites reach maximum, which are 36.6 %, 12.7 % and 16.3 % higher respectively than those of MC nylon.
基金funded by the projects of the National Public Welfare Industry (Agriculture) R&D Program,China (201303061)the China Agricultural Research System (CARS-39)
文摘Alfalfa (Medicago sativa) is difficult to ensile successfully because of the low content of moisture and water-soluble carbohydrates (WSC) in fresh alfalfa and the high buffering capacity in fresh alfalfa. Here, we conducted a study to evaluate the effects of three lactic acid bacteria (LAB) inoculants (Lactobacillus case/, lactobacillus plantarum, and Pediococcus pentosaceus) on silage quality, in sitE/ruminal degradability, and in vitro fermentation of alfalfa silage. The first cut of alfalfa was wilted, chopped, and randomly divided into four groups: the control (CON) and control mixed with three separate LAB inoculants (106 cfu g-1). Simmental steers with a body weight of (452±18) kg and with installed rumen fistulas were prepared for in situ degradation and for in vitro gas production. LAB inoculants had a lower (P〈0.05) content of butyric acid than the CON group. Among them, the L. casei inoculated silage had a higher (P〈0.05) content of water-soluble carbohydrate (WSC) and a lower (P〈0.05) NH3-H content. The effective degradation (ED) of crude protein in LAB inoculation decreased (P〈0.05), while the ED of acid detergent fiber increased (P〈0.05) in situ fermentation. The alfalfa silage with LAB inoculants produced more carbon dioxide (P〈0.05). The NH3-H content of mixed incubation fluid in L. casei inoculated silage was lower (P〈0.05) compared with other groups. Therefore, this study showed that LAB inoculants could improve both ensiling quality and degradation. In particular, the L. casei inoculations exhibited better performance by limiting proteolysis during ensiling.
文摘This study was carried out to determine nutritive value of pomegranate pomace using in situ and gas production techniques. In this study, two fistulated wethers (38 ± 1.5 kg) were used in situ method. The gas production was measured at 2, 4, 6, 8, 12, 16, 24, 36 and 48 h and ruminal DM (dry matter) and CP (crude protein) disappearances were measured at 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h. DM degradabilities of treated pomegranate pomace at 8 h to 96 h were larger than untreated pomegranate pomacewhich showed significant differences (p 〈 0.05). CP degradabilities of treated pomegranate pomace at 96 h was 62.38% that showed significant differences (p 〈 0.05). The metabolizable proteins of treated and untreated pomegranate pomace were 73 and 64.27 g/kg respectively that showed significant differences (p 〈 0.05). The gas productions of treated and untreated pomegranate pomace at 48 h were 79.91 and 128.75 mL/g DM respectively that showed significant differences (p 〈 0.05). It was concluded that the pomegranate pomace can be used largely as ruminant feeds.