Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-08
Xiaoli Li
Mengxin Xu
Yuan He
Zehua Liang
Shengxue Zhang
Chunlong Li
Lubei Liu
Qitong Huang
Tong Liu
Jiyu Wang
Guochang Liu
Zhi Wang
Tiancai Jiang
Pinan Xiang
Zhijun Wang
Yangyang Yang
Abstract： For the superconducting linac section of the Chinese Accelerator Driven Transmutation Research facility (CiADS) operating in continuous wave (CW) mode, the effect of cavity detuning caused by fluctuations of liquid helium pressure is an important factors for stable operation of low β cavities. Aiming at the phenomenon of unstable operation of half-wave superconducting resonators affected by helium pressure fluctuations, and taking the half-wave superconducting resonator with a frequency of 162.5 MHz and an optimal beta of 0.19(HWR019) applied in CiADS superconducting linac section as an example, the fluctuation of liquid helium pressure and the frequency variation law of the cavity was simulated with the method of numerical simulation. By calculating and analyzing the relationship between the contact area of liquid helium in the cavity, the wall thickness of the cavity, the shape of the liquid helium cooling channel, and the helium pressure sensitivity coefficient (KPress) of the cavity, the goal of reducing the (KPress) value of the HWR019 superconducting cavity to close to 0 was achieved, which effectively ensures the stable operation of the superconducting cavity in CiADS. At the same time, by conducting thermodynamic calculations on the cavity, corresponding enhanced heat transfer schemes were provided, effectively reducing the maximum temperature of the superconducting cavity during operation. The analysis and optimization methods also have reference significance for the same type of low β superconducting cavities.
Subjects: Biology >> Botany submitted time 2018-03-27 Cooperative journals: 《广西植物》
Abstract：林下植被是生态系统的重要组成成分，在维持森林垂直结构中发挥着不可或缺的作用。为了研究不同更新方式下桉树人工林林下植物功能群的变化规律及其主要影响因素，综合运用野外调查和室内分析的方法，评估桉树人工林林下植物功能群的组成、分布及更新方式和相关环境因子之间的关系。研究结果表明：林分更新5年后，除了非禾本科杂草功能群外，其他林下植物功能群的物种丰富度均呈现不同程度的增加，但与对照组（砍伐迹地）相比，其差异程度均不显著（P> 0.05）；与对照组相比，藤本和蕨类功能群的相对多度也出现增加趋势，但禾本科草本功能群显著减少（P< 0.05）；木本、藤本和蕨类功能群的相对盖度也呈现增加趋势，但禾本科草本功能群与对照组相比显著减少（P< 0.05）；主成分分析（PCA）发现萌芽更新或植苗更新林的林下植物功能群组成和分布与对照组相比均发生了显著的变异，但不同更新方式（萌芽和植苗）下其林下植物功能群组成和分布差异不明显；通过冗余分析（RDA）确定了冠层透光系数、土壤孔隙度、坡向和土壤氮磷比是影响该林地林下植物功能群的主要因子，它们的叠加效应能解释大于75%的林下植物功能群的变异，最终模型通过排序得到冠层透光系数是影响该林地林下植物功能群的最主要因子。短期的研究发现萌芽和植苗这两种不同的更新方式对桉树林下植物功能群的影响有限，这可能与这两种更新方式形成的林冠结构和土壤理化性质差异性较小有关。
Subjects: Biology >> Zoology submitted time 2017-10-10 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在研究饲粮中添加不同水平苜草素对蛋鸡胆固醇代谢的影响，并探讨其基因表达调控机制。选取体重和产蛋率相近的26周龄尼克蛋鸡540只，随机分为5组，每组6个重复，每个重复18只。对照组饲喂基础饲粮，试验组分别在基础饲粮中添加300、600、900、1 200 mg/kg的苜草素。预试期7 d，正试期70 d。结果表明：1）试验第35天和第70天，900 mg/kg苜草素组的蛋黄胆固醇含量显著低于对照组（P＜0.05）。2）与对照组相比，900 mg/kg苜草素组显著升高了蛋鸡血清中高密度脂蛋白胆固醇（HDL-C）含量和高密度脂蛋白/低密度脂蛋白（HDL/LDL）（P＜0.05），各组蛋鸡血清中总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白胆固醇（LDL-C）含量差异均不显著（P＞0.05）。3)与对照组相比，600、900、1 200 mg/kg苜草素组显著降低了蛋鸡肝脏中3-羟基-3-甲基戊二酸单酰辅酶A还原酶（HMGCR）mRNA表达量（P＜0.05），900和1 200 mg/kg苜草素组显著升高了蛋鸡肝脏组织中胆固醇7α-羟化酶（CYP7A1）mRNA表达量（P＜0.05）。各组蛋鸡肝脏中固醇结合蛋白元件-2（SERBP-2）和卵巢中卵黄蛋白原受体（OVR）mRNA表达量无显著差异（P＞0.05）。综上，饲粮中添加苜草素降低了蛋黄胆固醇和全蛋胆固醇含量，其调控机制可能是通过抑制蛋鸡胆固醇的内源性合成和促进胆固醇向胆汁酸的转化排泄2种途径来实现。本试验推荐26～35周龄蛋鸡苜草素添加水平为900 mg/kg。
Hits
YES
Hits
Downloads
Comment