Alpine meadows,comprising the main ecosystem of the Three-River Source Region,play an important role in the economic development of western pastoral areas.To determine whether the grazing level was too intense or the ...Alpine meadows,comprising the main ecosystem of the Three-River Source Region,play an important role in the economic development of western pastoral areas.To determine whether the grazing level was too intense or the nutrient-carrying capacity of the meadows was overloaded,and to offer solutions in Maqin County,Qinghai Province,China,the meadows carrying capacity was determined by combining grass-yield and nutrients data for different seasons across different meadows.The results showed that the levels of crude protein(CP),ether extract(EE),ash,soluble sugars(SS),gas production,and energy value of forage in the summer–autumn grazing meadows were higher than those of the winter–spring meadows.Neutral detergent fiber(NDF)and acid detergent fiber(ADF)of forage in the summer–autumn grazing meadows were lower than those of the winter–spring meadows.We found that no pastures were overloaded with metabolizable energy(ME)for the whole year but digestible crude protein(DCP)was overloaded in winter–spring.And there were differences in the amount carrying capacity(forage yield)of seasonal grazing meadows for the different herds,the overload types were annual overloading(herd A),overloaded in summer–autumn(herd B),overloaded in winter–spring(herd C),and not overloaded(herd D).Compared with the previous grazing mode,theoretical carrying capacity,DCP carrying capacity,and ME carrying capacity of herd A increased by 20,19,and 27 sheep units,respectively,after optimization;herd B:36,31,and 45 sheep units,respectively;herd C:28,23,and 44 sheep units,respectively;and herd D:43,40,and 61 sheep units,respectively.In the Three-River Source Region and similar alpine pastoral areas,the grassland-livestock structure should be optimized to improve grassland vegetation status and increase the theoretical carrying capacity.展开更多
尿石素A具有许多优良的生理活性,但其极低的水溶性和生物利用率限制了尿石素A的应用。为克服上述限制,该文采用pH驱动法结合高压均质技术制备尿石素A脂质体(urolithin A liposomes,UA-LPs),并考察其结构特性、稳定性及体外消化特性。结...尿石素A具有许多优良的生理活性,但其极低的水溶性和生物利用率限制了尿石素A的应用。为克服上述限制,该文采用pH驱动法结合高压均质技术制备尿石素A脂质体(urolithin A liposomes,UA-LPs),并考察其结构特性、稳定性及体外消化特性。结果表明,大豆卵磷脂为20 mg/mL所制得的UA-LPs的平均粒径为(97.46±0.83)nm,多分散系数为(0.27±0.01),Zeta电位为(-40.3±1.06)mV,包埋率为(98.11±0.26)%,负载率为(2.39±0.01)%。UA-LPs在原子力显微镜下为分布均匀的球状结构。热稳定性实验表明,不同大豆卵磷脂浓度的UA-LPs的包埋率均随热处理时间的延长有所下降,20 mg/mL的大豆卵磷脂制备的UA-LPs具有最好的热稳定性,其在80℃处理180 min后仍可保留45%的尿石素A,且粒径、多分散系数变化趋势较小。pH稳定性表明UA-LPs在酸性条件下包埋率较低,随着pH的升高,粒径、多分散系数变化不显著(P>0.05),20 mg/mL的大豆卵磷脂制备的UA-LPs的Zeta电位绝对值上升5.5,稳定性升高。体外模拟消化实验表明,UA-LPs能有效提高尿石素A的转化率以及生物可接受度,其中20 mg/mL大豆卵磷脂制备的UA-LPs的体外转化率相比游离的尿石素A增加了3.26倍,生物可接受度提高2.07倍。因此,利用pH驱动法可以成功制备出UA-LPs,且高大豆卵磷脂浓度的UA-LPs物理稳定性更好,以上研究结果为扩展尿石素A在食品工业及生物医药领域的应用提供依据。展开更多
目的确定体外消化透析法测定朱砂中汞的生物可接受率的实验条件,建立实验流程,并测定朱砂中汞的生物可接受率。方法模拟胃肠消化环境,研究pH、接触时间等因素对朱砂中汞的溶出率及透析时间等对朱砂中汞的生物可接受率的影响规律,确定合...目的确定体外消化透析法测定朱砂中汞的生物可接受率的实验条件,建立实验流程,并测定朱砂中汞的生物可接受率。方法模拟胃肠消化环境,研究pH、接触时间等因素对朱砂中汞的溶出率及透析时间等对朱砂中汞的生物可接受率的影响规律,确定合适模拟条件。结果确定的实验流程模拟条件为:液/固比100,人工胃液pH=1.5,加入0.16%胃蛋白酶1 m l,接触时间100 m in,透析时间100 m in,加入胰液胆盐混合物量为5 m l。在确定的实验条件下,CV-AFS测得水飞朱砂中汞的溶出率为2.5×10-6(n=6,RSD=4.1%),生物可接受率为4.8×10-7(n=6,RSD=3.5%)。结论体外消化透析法可用于测定朱砂中汞的生物可接受率,可为测定含朱砂中成药中汞的生物可接受率提供方法学上的参考。展开更多
基金supported by the National Key Project of Research and Development(2016YFC0501904-03)Key Laboratory of Superior Forage Germplasm in the Qinghai-Tibetan Plateau(2017-ZJY12)。
文摘Alpine meadows,comprising the main ecosystem of the Three-River Source Region,play an important role in the economic development of western pastoral areas.To determine whether the grazing level was too intense or the nutrient-carrying capacity of the meadows was overloaded,and to offer solutions in Maqin County,Qinghai Province,China,the meadows carrying capacity was determined by combining grass-yield and nutrients data for different seasons across different meadows.The results showed that the levels of crude protein(CP),ether extract(EE),ash,soluble sugars(SS),gas production,and energy value of forage in the summer–autumn grazing meadows were higher than those of the winter–spring meadows.Neutral detergent fiber(NDF)and acid detergent fiber(ADF)of forage in the summer–autumn grazing meadows were lower than those of the winter–spring meadows.We found that no pastures were overloaded with metabolizable energy(ME)for the whole year but digestible crude protein(DCP)was overloaded in winter–spring.And there were differences in the amount carrying capacity(forage yield)of seasonal grazing meadows for the different herds,the overload types were annual overloading(herd A),overloaded in summer–autumn(herd B),overloaded in winter–spring(herd C),and not overloaded(herd D).Compared with the previous grazing mode,theoretical carrying capacity,DCP carrying capacity,and ME carrying capacity of herd A increased by 20,19,and 27 sheep units,respectively,after optimization;herd B:36,31,and 45 sheep units,respectively;herd C:28,23,and 44 sheep units,respectively;and herd D:43,40,and 61 sheep units,respectively.In the Three-River Source Region and similar alpine pastoral areas,the grassland-livestock structure should be optimized to improve grassland vegetation status and increase the theoretical carrying capacity.
文摘目的确定体外消化透析法测定朱砂中汞的生物可接受率的实验条件,建立实验流程,并测定朱砂中汞的生物可接受率。方法模拟胃肠消化环境,研究pH、接触时间等因素对朱砂中汞的溶出率及透析时间等对朱砂中汞的生物可接受率的影响规律,确定合适模拟条件。结果确定的实验流程模拟条件为:液/固比100,人工胃液pH=1.5,加入0.16%胃蛋白酶1 m l,接触时间100 m in,透析时间100 m in,加入胰液胆盐混合物量为5 m l。在确定的实验条件下,CV-AFS测得水飞朱砂中汞的溶出率为2.5×10-6(n=6,RSD=4.1%),生物可接受率为4.8×10-7(n=6,RSD=3.5%)。结论体外消化透析法可用于测定朱砂中汞的生物可接受率,可为测定含朱砂中成药中汞的生物可接受率提供方法学上的参考。
