Energy filter with fast-counting direct electron detector

Julius-Maximilians-Universität w<e:1> rzburg的研究人员研究了生物组装支持多种功能的结构决定因素。2018年，他们建立了一个用于高分辨率结构测定的电子冷冻显微镜设备。这个设施被<s:1>茨堡内外的研究人员使用。该平台的核心是一台300千伏的电子显微镜，配有肖特基型XFEG发射器和直接电子探测器。该检测器允许在线性模式和计数模式下进行数据采集。后者给出了接近理论极限的探测量子效率。然而，由于它的低帧率，它限制了吞吐量，每天只有大约700部电影。相比之下，线性模式允许每天多达7000部电影的数据采集，但只有计数模式的一半左右的探测量子效率。由于在该设施获得的数据取得了成功，JMU研究人员的雄心壮志已经转向更具挑战性的项目，如更小、更动态的复合物和药物发现的配体定位。这些项目的成功取决于以计数模式获得的约5000部电影的大型数据集。以目前的设备，获取这样的数据集可能需要一周甚至更长时间。更糟糕的是，对于较小的动态复合物（< 150kda）， 24小时内获得的侦察数据往往不足以判断如果获得更大的数据集，是否有可能解决一个结构。因此，目前采用慢速计数相机的检测系统，在24小时内获得的图像数据的质量和数量方面，并不能满足JMU研究人员的需求和抱负。为了确定一种不同的检测系统是否更适合这些需求，研究人员比较了在w<s:1> rzburg和其他地方获得的相同样本的数据。这些比较表明，除了计数之外，能量过滤和零损耗成像是其他重要的资产，可以对小型动态复合物进行更稳健的分类，并大大提高整体分辨率。为了使平台在图像采集方面达到目前的领先标准，我们申请用能量滤波器和具有快速计数功能的直接电子探测器取代当前的检测系统。

Researchers at the Julius-Maximilians-Universität Würzburg investigate the structural determinants by which biological assemblies support a diverse set of functionalities. In 2018 they established an electron cryo microscopy facility for high-resolution structure determination. This facility is used by researchers in and beyond Würzburg. At the heart of the platform is a 300 kV electron microscope with a Schottky type XFEG emitter and a direct electron detector. The detector enables data acquisition in linear mode and in counting mode. The latter gives a detective quantum efficiency, which is close to the theoretical limit. However, due to its low frame rate it limits the throughput to only about 700 movies per day. In contrast, linear mode allows data acquisition of up to 7,000 movies a day but with only about half of the detective quantum efficiency of the counting mode. Sparked by the success with data obtained at the facility, the ambitions of the researchers at the JMU have shifted towards more challenging projects such as smaller, and more dynamic complexes and ligand localization for drug discovery. The success of these projects depends on large data sets with some 5000 movies obtained in counting-mode. With the current equipment, acquisition of such data sets can take a week and more. Even worse, for smaller dynamic complexes (< 150 kDa), the scouting data obtained within 24 hours are often insufficient for judging whether a structure would likely be solved if a larger data set were obtained. Therefore, the current detection system with a slowly counting camera does not fulfill the needs and ambitions of the researchers at the JMU with respect to quality and quantity of image data obtained within a 24-hour slot. To establish whether a different detection system will be more suitable for the needs, researchers compared data obtained for the same sample in Würzburg and elsewhere. These comparisons showed that in addition to counting, energy filtration and zero-loss imaging are other important assets which enable more robust classification of small dynamic complexes and drastically improve the overall resolution. To bring the platform to the current leading standards in image acquisition, we apply for replacing the current detection system with an energy filter and a direct electron detector with fast counting capabilities.