Improvement of XFEL bio-nano imaging with statistical analysis

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03497
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
• Research Institution: Japan Synchrotron Radiation Research Institute
• Principal Investigator: Joti Yasumasa 公益財団法人高輝度光科学研究センター, XFEL利用研究推進室, 主幹研究員 (30360415)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: コヒーレント回折イメージング / X線レーザー / 生物物理 / 位相回復 / 実験データ解析 / ノイズ除去

Outline of Final Research Achievements

To understand the biological phenomenon, it is essential to capture the transient instantaneous structure of the biological nanoparticles, when they are expressing their functions. Coherent diffractive imaging (CDI), using XFEL with ultrashort pulse, has the potential to achieve that. For that, it is necessary to develop a phase retrieval method that reproduces a plausible electron density of a sample from experimental data that includes background scattering from sources other than the sample, detection noise, and dead zones of the detector, and to quantify the reliability of the result of the phase retrieval.
In this study, we have developed a method for the purpose as planned, but it was found that the background scattering and detection noise of the experimental data were more serious than expected. The future challenge is to improve the method to have high noise resistance.

Free Research Field

計算生物物理学

Academic Significance and Societal Importance of the Research Achievements

位相回復法は、コヒーレント回折パターン解析に必須のものであるが、試料以外からの背景散乱を系統的に扱う手法はこれまで存在しなかった。また、理想的な回折パターンではない実験データを扱う場合、再生された電子密度像の信頼性は本来部位特異的であるはずだが、これまでは部位に依存しない一つの指標のみで評価されてきた。本研究では、適用範囲に限界はあるものの、これらの問題に対応した新規手法を開拓することができた。さらなる実用化に向けて研究を進めたい。