Peter Hoghoj

High-throughput biological solution SAXS instrumentation for the home laboratory

The high throughput nature of the instrument and the ability to automatically mix sample components shortly before measurements facilitates the study of biomolecular kinetics that was previously not possible in an automated fashion on a lab source SAXS instrument. This level of automation allows for automatic screening in time resolved studies in the minutes to hours scale, and greatly increases productivity.

IYCr Open Factory: Inviting Young Crystallographers to Europe – Status & Outlook

The STOE DECTRIS Xenocs OpenFactory will take place from 10 to 19 September 2014. Participants receive seven days of intensive training by STOE, DECTRIS and Xenocs staff and guest scientists in cooperation with the IUCr. The training will focus on teaching participants the relevant theoretical skillset as well as giving practical training. In Grenoble, the delegates will spend significant time at the ESRF (European Synchrotron) and will be trained in Small Angle X-ray scattering at Xenocs’ headquarters. In Darmstadt, the participants will be trained in Single Crystal and Powder XRD at STOE’s headquarter. Delegates will have the opportunity to visit beamlines and interact with scientists at ESRF. Starting on 18 September, all OpenFactory participants will join the STOE annual user meeting. The user meeting is a platform for the exchange of ideas among its participants as well as speeches to highlight recent research results. It will be a unique opportunity for OpenFactory participants to interact with highly experienced XRD users and to build up relevant networks. This presentation and poster will highlight the activity, the focus of the program and present the selected participants for the OpenFactory event. The intention is to update on the status of the OpenFactory, but even more important, to encourage similar activities within and after the International Year of Crystallography. In this context, the presenter will discuss any insights from the applications received, i.e. geographies with particular high interest in the OpenFactory, which could be used to follow up on the OpenFactory with future events.

Macromolecule solution studies with high brilliance, low background SAXS camera

Small angle x-ray scattering technique is a powerful method to study the 3D envelope of proteins or the arrangement of individual domains in protein complexes through minimized sample preparation. SAXS is thus becoming a mainstream technique to study macromolecules in solutions in an interdisciplinary approach combined with NMR and Electron Microscopy. This is symbolized by a fast growing number of structures published, and initiatives on SAS structures publication guidelines[1]. Progress in instrumentation also led to emergence of high quality laboratory bio SAXS equipments. We will present the impact of relevant equipment features on structure characterization through data measurements examples on various protein samples. Using a high flux with controlled beam properties (size and divergence) at detector plane is important to achieve sufficient signal to noise at larger wave vectors (Q) range together with the capability to measure large protein complexes (related to minimum wave vector detectable, Qmin). We will be discussing figure of merits for evaluating data quality at high Q range and presenting the impact of incident flux and various detection schemes on such criteria. Data measurements on large protein complexes will be shown highligthing the impact of instrument Qmin. Low backgroung scattering generation inside SAXS camera and low noise detection are other critical requirements for faithful and accurate sample to buffer data subtraction. A new generation of scatterless collimation with variable resolution, and improved sample environments open the door to unprecedented ratios of primary beam intensity to background and to measurements on weakly scattering samples. Impact on data quality will be emphasized. Data processing and struture modeling of various proteins of different sizes acquired with laboratory SAXS camera using low maintenance high brighness source will be presented and compared to synchrotron data.

Particle sizing and counting with accurate SAXS measurements

Small Angle X-Ray Scattering (SAXS)[1] is a technique well suited for investigating the structure of materials in the range from 1 to beyond 100 nm. The technique gives information on sample structure parameters such as shape or size, size distribution, orientation and anisotropy, surface to volume ratio. X-ray radiation enables to penetrate sample and typically probes a sample volume from 0.11 mm3. The information on structure is therefore obtained from inside the sample and is statistically representative of the sample volume probed. Furthermore, little sample preparation is needed and the technique is non-destructive. Developments in instrumentation (sources and detection) enable to observe fast changes in the sample as a function of parameters such as (but not limited to) temperature. The capability of laboratory based solutions for characterization at the nano-scale is recognized in the ISO standard currently being drafted [2] on measurement of particle size. We will show different examples of particle sizing and sizedistribution measurements with SAXS, including particle/matrix with low electronic contrast and poly-dispersity studies. Comparisons will be done with alternative methods such as light scattering techniques. Stable and accurate measurement of incident and scattering intensity offers capability for particle sizing, further it allows for counting or surface to volume ratio determination providing valuable information in industrial applications such as nanoparticle sizes quantification in complex matrix (automotive) or nano porous material structure characterization for catalysts as few examples.

SAXS studies of protein solutions using high-brilliance clean beam and low-background camera

Successful developments of applications in synchrotron beamlines have led to an increase need for high quality laboratory equipments. We will present the latest features and results with the Xeuss SAXS/WAXS equipment from Xenocs on low concentration protein solutions. A new generation of scatterless collimation with variable resolution opens the door to unprecedented ratios of primary beam intensity to background and to measurements on weakly scattering samples.

Generating high brilliance X-ray beams for X-ray diffraction and scattering applications

Today a large fraction of the X-ray analytical systems used in two-dimensional diffraction and scattering applications are still equipped with non-optimized beamgenerating schemes that combine high power sealed tubes or rotating anodes with large source-sizes with inefficient optical schemes. With the advent of single reflection graded multilayer optics and efficient, low power micro-focus sealed tubes, it has become advantageous and cost-effective to replace these high power systems with this more efficient and robust technology.