我們使用朗之萬動力學模擬 (Langevin dynamics simulation) 使用尺度研究柔軟的高分子鍊從球形空腔通過奈米孔洞注射到另一個半空間。
使用尺度理論 (scaling theory)，注射時間被預測為 τ∼N^a ϕ_0^b，N 為高分子鏈長，ϕ_0 為高分子在空腔內的體積占比。
我們的模擬結果顯示注射時間有兩個主要的尺度行為: (i) 當 ϕ_0 很大時， τ∼N^1.51 ϕ_0^-1.11， (ii) 當 ϕ_0 很小時，τ∼N^2.30。
此外，注射過程可被區分為成核階段 (nucleation stage)、壓縮階段和非壓縮階段。
在壓縮階段，空腔內的高分子被腔壁所擠壓，而在非壓縮階段則空腔內的高分子不被腔壁所擠壓所以可以被視為無傾向的易位 (unbiased translocation)。
在此研究中，我們合併使用消散理論 (dissipation theory ) 和無傾向的易位的觀念來解釋注射時間的尺度行為。

Langevin dynamics simulations are performed to study ejection of flexible polymers from a spherical cavity through a nanopore to a semi-space.The ejection time is predicted by a scaling theory and reads as τ∼N^a ϕ_0^b where τ, N and ϕ_0 are the ejection time, the chain length, and the initial volume fraction of the polymer confined in the spherical cavity, respectively.Our simulations show two scaling behaviors for the ejection time: (i)τ∼N^1.51 ϕ_0^-1.11 for large ϕ_0 and (ii) τ∼N^2.30 for small ϕ_0.Besides, the ejection process can be divided into there stages.The first stage is the nucleation stage.The second one is the compressed stage, at which the polymer inside the cavity is compressed by the cavity wall.The third one is the uncompressed stage, at which the polymer inside the cavity is uncompressed and the process is viewed as the unbiased translocation process.The scaling behavior of ejection time is studied by a combination of energy dissipation and the concept of unbiased translocation.

Acknowledgements i
Abstract ii
1 Introduction 1
2 Scaling Theory 4
2.1 Polymer Ejection 4
2.2 Unbiased translocation 8
2.3 Summary 9
3 Simulation Model and Method 11
3.1 Polymers 11
3.2 Capsids and pores 12
3.3 Unbiased translocation 13
3.4 Langevin dynamics 13
3.5 Simulation processes 14
3.6 A constraint of the end bead 15
3.7 Ejection time 15
4 Results and Discussions 16
4.1 Prediction of ejection time 16
4.2 Dynamics of ejection 18
4.3 Scalings of translocation time 22
4.4 Jamming effect 23
5 Conclusions 28
Bibliography 30

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