In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperat...In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperature dependence of the MM-map is examined based on high-temperature molecular dynamics simulations and infrared （IR） experiments. It is shown that the 298-K map works for up to 500-K molecular dynamics trajectories, which reasonably reproduces the 88 ℃ experimental IR results. Linear IR spectra are also simulated for two tripeptides containing natural and unnatural amino acid residues, and the results are in reasonable agreement with experiment. The results suggest the MM-map can be used to obtain the temperature-dependent amide-Ⅰ local mode frequencies and their distributions for peptide oligomers, which is useful in particular for understanding the IR signatures of the thermally unfolded species.展开更多
The idea that the collapse proceeds from the outer boundary of the cavity cloud towards its center for the ultrasonic cavitation proposed by Hasson and Morch in 1980s is further developed for calculating the collapse ...The idea that the collapse proceeds from the outer boundary of the cavity cloud towards its center for the ultrasonic cavitation proposed by Hasson and Morch in 1980s is further developed for calculating the collapse pressure and boundaries of cavity cloud at the collapse stage of bubbles for hydraulic cavitation flow in Venturi in present research. The numerical simulation is carried out based on Gilmore＇s eouations of bubble dynamics, which take account of the compressibility of fluid besides the viscosity and interfacial tension. The collapse of the cavity cloud is considered to proceed layer by layer from the outer cloud towards its inner part. The simulation results indicate that thepredicted boundaries of the cavity cloudat the collapse stage agree.well with the exPerimental ones.It is also found that the maximum collapse pressure of the cavity cloud is several times as high as the collapse pressure of outside boundary, and it is located at a point in the axis, where the cavity cloud disappears completely. This means that a cavity cloud has higher collapse pressure or strength than that of a single bubble due to the interactions of the bubbles. The effects of operation and structural parameters on the collapse pressure are also analyzed in detail.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.30870591）, the National Basic Research Program of China （No.2007CB815205） and the Chinese Academy of Sciences （Hundred Talent Fund）. Chen Han thanks Dr. Kai-cong Cai for helpful discussions.
文摘In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperature dependence of the MM-map is examined based on high-temperature molecular dynamics simulations and infrared （IR） experiments. It is shown that the 298-K map works for up to 500-K molecular dynamics trajectories, which reasonably reproduces the 88 ℃ experimental IR results. Linear IR spectra are also simulated for two tripeptides containing natural and unnatural amino acid residues, and the results are in reasonable agreement with experiment. The results suggest the MM-map can be used to obtain the temperature-dependent amide-Ⅰ local mode frequencies and their distributions for peptide oligomers, which is useful in particular for understanding the IR signatures of the thermally unfolded species.
基金Supported by the National Natural Science Foundation of China （10472024）.
文摘The idea that the collapse proceeds from the outer boundary of the cavity cloud towards its center for the ultrasonic cavitation proposed by Hasson and Morch in 1980s is further developed for calculating the collapse pressure and boundaries of cavity cloud at the collapse stage of bubbles for hydraulic cavitation flow in Venturi in present research. The numerical simulation is carried out based on Gilmore＇s eouations of bubble dynamics, which take account of the compressibility of fluid besides the viscosity and interfacial tension. The collapse of the cavity cloud is considered to proceed layer by layer from the outer cloud towards its inner part. The simulation results indicate that thepredicted boundaries of the cavity cloudat the collapse stage agree.well with the exPerimental ones.It is also found that the maximum collapse pressure of the cavity cloud is several times as high as the collapse pressure of outside boundary, and it is located at a point in the axis, where the cavity cloud disappears completely. This means that a cavity cloud has higher collapse pressure or strength than that of a single bubble due to the interactions of the bubbles. The effects of operation and structural parameters on the collapse pressure are also analyzed in detail.
