The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments ...The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments have predicted that the shielding ice formed on the hydrate surface after initial dissociation of the hydrate plays an important role in the self-preservation effect. We propose ice-shielding models of gas hydrates to investigate the dissociation rates quantitatively, including the self-preservation process, at temperatures below the ice-melting point and at atmospheric pressure. Three general models are constructed for two temperature ranges The rate-determining process for the lower temperature range is hydrate dissociation, and those for the higher range are gas diffusion through ice or hydrate layers, which depend on the thickness of the shielding-ice layer. Our models suggest that the extent of self-preservation depends on temperature, original hydrate size, and guest substances, which can explain the experimental results.展开更多
A anified plasma sheath model and its potential equation are proposed. Any higher-ordor-approximation analytical solutions for the unified plasma sheath potential equa tiop are derived by double decomposition method.
Promising high strangeness dibaryons are studied by the extended quark delocalization and color screeningmodel. It is shown that besides H particle and di-Ω, there might be other dibaryon candidates worth to be searc...Promising high strangeness dibaryons are studied by the extended quark delocalization and color screeningmodel. It is shown that besides H particle and di-Ω, there might be other dibaryon candidates worth to be searchedexperimentally such as NΩ.展开更多
水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后...水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后的水飞蓟种壳粉为原料,用初步筛选所得较优NADES,即:氯化胆碱+1,4-丁二醇进行提取,HPLC法测定水飞蓟宾含量,在单因素实验基础上,采用响应面法对该NADES提取水飞蓟宾工艺进行优化。结果表明:料液比1:20 g/mL,提取温度77.0℃、时间5.6 h,模型预测水飞蓟宾得率可达4.29%,与实验值4.30%基本一致。基于片段活度系数类导体屏蔽模型(Conductor-like Screening Model for Segment Activity Coefficient,COSMO-SAC),分别对水飞蓟宾和溶剂分子(NADES与传统溶剂乙醇)进行结构与能量优化,通过量子化学计算,得到水飞蓟宾在两种溶剂中的无限稀释活度系数的对数分别为-6.922和-6.043,分子间相互作用能分别为-51.62和-25.47 kJ/mol,以探讨不同溶剂提取水飞蓟宾效果差异机理。展开更多
The gluon and Goldstone boson induced tensor interaction effect on thedibaryon mass and the D-wave decay width has been studied in the quark delocalization, colorscreening model. The effective S-D wave transition inte...The gluon and Goldstone boson induced tensor interaction effect on thedibaryon mass and the D-wave decay width has been studied in the quark delocalization, colorscreening model. The effective S-D wave transition interactions induced by gluon and Goldstone bosonexchanges decrease quickly as the increasing of the channel strangeness. The K and η meson tensorcontribution is negligible in this model. No six-quark state in the light Savor world can become abound one by the help of these tensor interactions except the deuteron. The partial D-wave decaywidth of I J~p = (1/2) 2~+ NΩ state to spin 0, 1 ΛΞ final state is 20.7 keV and 63.1 keVrespectively. It is a very narrow dibaryon resonance and might be detected in the relativistic heavyion reaction by the existing RHIC detectors through the reconstruction of the ΛΞ vertex mass andthe future COMPAS detector at CERN and FAIR project in Germany.展开更多
在化工、能源、环境、食品和药物等工业设计过程中,真实混合物的可靠溶解度数据非常重要,不仅能丰富相平衡数据库,还能指导工艺设备设计和产品质量控制。本文介绍了烃-水体系相互溶解度的模型化研究,包括状态方程法、活度系数法和经验...在化工、能源、环境、食品和药物等工业设计过程中,真实混合物的可靠溶解度数据非常重要,不仅能丰富相平衡数据库,还能指导工艺设备设计和产品质量控制。本文介绍了烃-水体系相互溶解度的模型化研究,包括状态方程法、活度系数法和经验关联式,以及近年来发展起来的真实溶剂似导体屏蔽模型法(conductor-like screening model for real solvents,COSMO-RS)。状态方程法和活度系数法主要是通过选择非对称的混合规则以及引进描述水分子极性作用的参数,来改善对烃-水体系相互溶解度的计算精度。经验关联式主要是对实验数据的拟合,每种烃的参数不同。COSMO-RS模型根据密度泛函理论(即建立极化电荷密度的简单经验式)计算单个分子嵌入虚拟导体产生的作用,通过准确描述界面统计相互作用获得体系的热力学性质。因此,该方法对各种体系具有普适性。分析表明,COSMO-RS模型对烃-水体系相互溶解度的预测值与实验值吻合良好,可以补充某些难以通过实验获得的烃-水体系互溶度数据。最后总结和展望了烃-水体系相互溶解度模型化的未来发展方向。展开更多
文摘The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments have predicted that the shielding ice formed on the hydrate surface after initial dissociation of the hydrate plays an important role in the self-preservation effect. We propose ice-shielding models of gas hydrates to investigate the dissociation rates quantitatively, including the self-preservation process, at temperatures below the ice-melting point and at atmospheric pressure. Three general models are constructed for two temperature ranges The rate-determining process for the lower temperature range is hydrate dissociation, and those for the higher range are gas diffusion through ice or hydrate layers, which depend on the thickness of the shielding-ice layer. Our models suggest that the extent of self-preservation depends on temperature, original hydrate size, and guest substances, which can explain the experimental results.
文摘A anified plasma sheath model and its potential equation are proposed. Any higher-ordor-approximation analytical solutions for the unified plasma sheath potential equa tiop are derived by double decomposition method.
基金The project supported by National Natural Science Foundation of China under Grant No.90103018
文摘Promising high strangeness dibaryons are studied by the extended quark delocalization and color screeningmodel. It is shown that besides H particle and di-Ω, there might be other dibaryon candidates worth to be searchedexperimentally such as NΩ.
文摘水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后的水飞蓟种壳粉为原料,用初步筛选所得较优NADES,即:氯化胆碱+1,4-丁二醇进行提取,HPLC法测定水飞蓟宾含量,在单因素实验基础上,采用响应面法对该NADES提取水飞蓟宾工艺进行优化。结果表明:料液比1:20 g/mL,提取温度77.0℃、时间5.6 h,模型预测水飞蓟宾得率可达4.29%,与实验值4.30%基本一致。基于片段活度系数类导体屏蔽模型(Conductor-like Screening Model for Segment Activity Coefficient,COSMO-SAC),分别对水飞蓟宾和溶剂分子(NADES与传统溶剂乙醇)进行结构与能量优化,通过量子化学计算,得到水飞蓟宾在两种溶剂中的无限稀释活度系数的对数分别为-6.922和-6.043,分子间相互作用能分别为-51.62和-25.47 kJ/mol,以探讨不同溶剂提取水飞蓟宾效果差异机理。
文摘The gluon and Goldstone boson induced tensor interaction effect on thedibaryon mass and the D-wave decay width has been studied in the quark delocalization, colorscreening model. The effective S-D wave transition interactions induced by gluon and Goldstone bosonexchanges decrease quickly as the increasing of the channel strangeness. The K and η meson tensorcontribution is negligible in this model. No six-quark state in the light Savor world can become abound one by the help of these tensor interactions except the deuteron. The partial D-wave decaywidth of I J~p = (1/2) 2~+ NΩ state to spin 0, 1 ΛΞ final state is 20.7 keV and 63.1 keVrespectively. It is a very narrow dibaryon resonance and might be detected in the relativistic heavyion reaction by the existing RHIC detectors through the reconstruction of the ΛΞ vertex mass andthe future COMPAS detector at CERN and FAIR project in Germany.
文摘在化工、能源、环境、食品和药物等工业设计过程中,真实混合物的可靠溶解度数据非常重要,不仅能丰富相平衡数据库,还能指导工艺设备设计和产品质量控制。本文介绍了烃-水体系相互溶解度的模型化研究,包括状态方程法、活度系数法和经验关联式,以及近年来发展起来的真实溶剂似导体屏蔽模型法(conductor-like screening model for real solvents,COSMO-RS)。状态方程法和活度系数法主要是通过选择非对称的混合规则以及引进描述水分子极性作用的参数,来改善对烃-水体系相互溶解度的计算精度。经验关联式主要是对实验数据的拟合,每种烃的参数不同。COSMO-RS模型根据密度泛函理论(即建立极化电荷密度的简单经验式)计算单个分子嵌入虚拟导体产生的作用,通过准确描述界面统计相互作用获得体系的热力学性质。因此,该方法对各种体系具有普适性。分析表明,COSMO-RS模型对烃-水体系相互溶解度的预测值与实验值吻合良好,可以补充某些难以通过实验获得的烃-水体系互溶度数据。最后总结和展望了烃-水体系相互溶解度模型化的未来发展方向。
