NCI X-ray free electron laser (XFEL) initiative

目前，两项实验正在进行中。1）. 利用XFEL研究配体触发核糖体开关构象变化的时间分辨过程。波束时间是根据我们在2019年的竞争性提案授予的，就在疫情关闭之前。2)与美国国家航空航天局（NASA）合作开展国际空间站（ISS）微重力环境下的纳米微米结晶研究。我们的样品已经在国际空间站上了。我们正在等待下一个窗口时间，届时宇航员可以在国际空间站上进行实验，并将样本送回地面，以便在LCLS上立即收集数据。在过去的五年中，由于样品返回计划的高度不确定性和确保XFEL光束时间满足样品返回计划的极大困难，安排该实验已被证明是极具挑战性的。去年与大流行有关的停工进一步加剧了这一问题。无论如何，我们将继续努力，直到实验最终成功地进行和完成。鉴于与疫情有关的中断，我对我们的计划进行了认真和战略性的改变。我们不得不采用不同的技术来开展和完成我们探索RNA结构动力学和构象空间的研究目标，而不是仅仅依靠我们无法控制且极易中断的资源XFEL。

Currently, two experiments are pending. 1). Investigating time-resolved process of ligand-triggered conformation change in riboswitch using XFEL. The beam time was awarded based on our competitive proposal in 2019, right before the pandemic shutdown. 2). nano-micron crystallization under the microgravity environment onboard of the International Space Station (ISS) under the collaboration with NASA. Our samples are already on board of ISS. We're waiting for the next window time where an astronaut can perform the experiment onboard of ISS and the samples are returned ground for the immediate data collection at LCLS. For the past five years, arranging this experiment has been proven to be extremely challenging because of high degree of uncertainty in sample return schedules and great difficulty in securing a XFEL beamtime to meet the sample returning schedule. The problem was exacerbated further by the pandemic related shutdown in the last year. Regardless, we will continue our effort till the experiment is eventually performed and completed successfully. In light of the pandemic related interruption, I have made a conscientious and strategic change in our program. Instead of solely relying on the XFEL, the resource that we have no control over and is highly susceptible to interruption, we were forced to adopt different technologies to carry out and fulfill our research goal of exploring RNA structural dynamics and conformational space.