Petrus H. Zwart's research while affiliated with Lawrence Berkeley National Laboratory and other places

... The last major component, the data connector, is under development. Additionally, we have implemented an assortment of web applications for scientific analysis of multimodal datasets, such as grain/pattern orientation detection, latent space exploration, peak detection for 1-dimensional Xray diffraction (XRD) data, inpainting detector gaps in X-ray scattering [17], and fast artifact identification for raw XRD images [18]. ...

... Is it possible to control their aggregation? [53][54][55][56][57] 3. What are the structural changes occurring in a pure or doped droplet after it has been subjected to intense light pulse such as near-infrared (NIR) radiation? [58][59][60][61]. ...

... For materials synthesis, multiple approaches including pipetting robots, 1,2 self-driving labs, [3][4][5] and high throughput synthesis workflows have been proposed. [6][7][8][9][10][11] For characterization, several groups are now developing automated experiment approaches in areas including scanning transmission electron microscopy, [12][13][14] scanning probe microscopy, [15][16][17][18][19] neutron 20,21 and X-ray scattering. 22 The central concept in automated experiments is the workflow, 23 defined as the sequence of steps and operations performed by the automated laboratory or the measurement tool. ...

... We propose to make use of Gaussian process (GP) regression for hyperspectral data collection [39][40][41][42][43] , which is a well-known method for function approximation and uncertainty quantification. This method refers to a set of function values, where any finite subset of elements have a joint Gaussian distribution. ...

... First, to enhance the formation of ICs, we passively administered, prior to immunization, a high-affinity macaque-derived monoclonal antibody (mAb) that targets the base of the soluble HIV Env trimer immunogen BG505 SOSIP. In a second strategy, to enhance MBL binding and subsequent complement deposition, we multimerized the BG505 SOSIP HIV Env trimer immunogen in a particulate form: we recently described the development and characterization of several different two-component self-assembling nanoparticles that present viral glycoprotein immunogens 37,38 . Here, we assessed the in vivo trafficking properties of one such nanoparticle, T33-dn2, presenting the BG505 SOSIP trimer and compared it to soluble Env trimer immunogen. ...

... Therefore, in high-dimensional spaces often more data has to be gathered, which correspondingly increases computational costs. See [31][32][33][34][35] for an overview of work on methods to speed up Gaussian process computations. ...

... Without exhaustive testing we are not able to tell precisely which differences provide the greatest improvement. A significant improvement can however be attributed to the error model used, which has been shown to improve merging on its own using a different approach (Brewster et al., 2019). Another important difference is that our method profits strongly from overprediction, adding many measurements with mostly insignificant intensities, by integrating reflections even if they are further removed from the ideal diffraction condition. ...

... In general, "seeing" their structures is the prerequisite to understanding their large-scale dynamics. While well-established techniques such as X-ray crystallography and cryo-electron microscopy investigate their structures in crystallized or frozen conditions, fluctuation X-ray scattering (FXS) [8] can measure non-crystallized biological particles dispersed in solutions in near-physiological conditions, which is promising for future dynamics study. This emerging technique is not only experimentally challenging but also has a theoretical difficulty in interpreting experimental data. ...

... 9,10 Fluctuation scattering can also be performed even when illuminating more than one particle in coherent diffraction measurements assuming that inter-particle interference can be neglected. 11,12 Illumination of more than one particle helps in enhancing the diffraction signal and will lead to a higher spatial resolution in particle imaging. Elser pointed out that ab initio three-dimensional imaging in fluctuation scattering generally requires unidirectionally-aligned particles, because there are information deficits for randomly oriented particles. ...

... Sunlight plays a critical role in the development of emerging sustainable energy conversion and storage technologies [3]. Light-matter interactions govern a large number of important photochemical and photophysical processes that ultimately determine the existence of life on the Earth, such as natural photosynthesis [4]. One of the most promising energy conversion strategies is to mimic natural photosynthesis by converting sunlight into fuels and valuable chemicals, using abundant feedstocks like water and carbon dioxide [5,6]. ...