Sebastian Jaksch

Forschungszentrum Jülich · Jülich Centre for Neutron Science (JCNS)

A mathematical model is developed to jointly analyze elastic and inelastic scattering data of fluctuating membranes within a single theoretical framework. The model builds on a nonhomogeneously clipped time-dependent Gaussian random field. This specific approach provides one with general analytical expressions for the intermediate scattering functi...

To meet the ever-increasing user demand, eleven of the fifteen European Spallation Source (ESS) instruments under construction aim to offer polarised neutrons for user experiments. They include an imaging instrument, a SANS instruments, two reflectometers, three diffractometers, and four spectrometers. In conjunction with in-kind contributions and...

In this manuscript we describe the investigation of the SARS-CoV2 membrane fusion timescale by means of small-angle neutron scattering (SANS) using hydrogen/deuterium contrast variation. After the successful production of virus-like vesicles and human-host-cell-like vesicles we were able to follow the fusion of the respective vesicles in real-time....

This manuscript describes a concept of a grazing incidence small-angle neutron scattering (GISANS) instrument for the high brilliance source (HBS). The HBS being a compact pulsed neutron source using a moderate energy proton accelerator which allows for very compact moderators and shielding, and flexible pulse repetition rates. Similar to many othe...

The static structure factor and the undulation dynamics of a solid-supported membrane stack have previously been calculated by Romanov and Ul’yanov [Romanov & Ul’yanov (2002). Phys. Rev. E, 66, 061701]. Based on this prior work, the calculation has been extended to cover the membrane dynamics, i.e. the intermediate scattering function as a Fourier...

We report on the structure and diffusion behaviour of the various constituent molecules in ionic liquid (IL) mixtures under confinement in nanoporous glasses. X-Ray diffraction measurements indicate that the ions adopt a lamellar arrangement under confinement. Furthermore, using selective deuteration in combination with high resolution neutron spec...

Small-angle scattering, and its neutron expression small-angle neutron scattering (SANS), has developed into an invaluable tool for the investigation of microscopic and mesoscopic structures in recent decades [...]

Many experimental methods are available for the characterization of nanostructures, but most of them are limited by stringent experimental conditions. When it comes to analysing nanostructures in the bulk or in their natural environment – even as ordinary as water at room temperature – small-angle scattering (SAS) of X-rays or neutrons is often the...

This article deals with multiple scattering effects that are important for the method of small-angle neutron scattering (SANS). It considers three channels for the coherent elastic, the incoherent elastic and the incoherent inelastic scattering processes. The first channel contains the desired information on the experiment. Its multiple scattering...

Converting neutron scattering data to real-space time-dependent structures can only be achieved through suitable models, which is particularly challenging for geometrically disordered structures. We address this problem by introducing time-dependent clipped Gaussian field models. General expressions are derived for all space- and time-correlation f...

Converting neutron scattering data to real-space time-dependent structures can only be achieved through suitable models, which is particularly challenging for geometrically disordered structures. We address this problem by introducing time-dependent clipped Gaussian field models. General expressions are derived for all space- and time-correlation f...

The European Spallation Source (ESS), which is under construction in Lund (Sweden), will be the leading and most brilliant neutron source and aims at starting user operation at the end of 2023. Among others, two small angle neutron scattering (SANS) machines will be operated. Due to the high brilliance of the source, it is important to minimize the...

We present a structural and dynamical analysis of the influence of NaCl on multilayer stacks of phospholipids on a solid surface. To this end, multilayer stacks of phospholipids (L-α-phosphatidylcholine, abbreviated as SoyPC) are investigated with neutron reflectometry, grazing-incidence small-angle neutron scattering (GISANS) and grazing-incidence...

The FlexiProb project is a joint effort of three soft matter groups at the Universities of Bielefeld, Darmstadt, and Munich with scientific support from the European Spallation Source (ESS), the small-K advanced diffractometer (SKADI) beamline development group of the Jülich Centre for Neutron Science (JCNS), and the Heinz Maier-Leibnitz Zentrum (M...

As part of the development of the new European Spallation Source (ESS) in Lund (Sweden), which will provide the most brilliant neutron beams worldwide, it is necessary to provide different sample environments with which the potential of the new source can be exploited as soon as possible from the start of operation. The overarching goal of the proj...

Small-K Advanced DIffractometer (SKADI is a Small-Angle Neutron Scattering (SANS) instrument to be constructed at the European Spallation Source (ESS). SANS instruments allow investigations of the structure of materials in the size regime between Angstroms up to micrometers. As very versatile instruments, they usually cater to the scientific needs...

The response of a position-sensitive Li-glass scintillator detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using collimated beams of thermal neutrons. The detector was moved perpendicularly through the neutron beams in 0.5 to 1.0 mm horizontal and vertical steps. Scintillation was detected...

The response of a position-sensitive Li-glass based scintillation detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using focused beams of 2.5 MeV protons and deuterons. The beams were scanned across the detector in 0.5 mm horizontal and vertical steps perpendicular to the beams. Scintillatio...

The response of a position-sensitive Li-glass scintillator detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using collimated beams of thermal neutrons. The detector was moved perpendicularly through the neutron beams in 0.5 to 1.0 mm horizontal and vertical steps. Scintillation was detected...

The response of a position-sensitive Li-glass based scintillation detector to focused beams of 2.5 MeV protons and deuterons has been investigated. The beams were scanned across the detector in 0.5 mm horizontal and vertical steps perpendicular to the beams. Scintillation light was registered using an 8 by 8 pixel multi-anode photomultiplier tube....

Drug-loaded polymer micelles or nanoparticles are being continuously explored in the fields of drug delivery and nanomedicine. Commonly, a simple core-shell structure is assumed, in which the core incorporates the drug and the corona provides steric shielding, colloidal stability, and prevents protein adsorption. Recently, the interactions of the d...

An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of theEuropean Spallation Source (ESS), and being made available to the neutron user community. The ESS neutronsource consists of a high-power accelerator and target station, providing a unique long-pulse time structureof slow neutrons. The design cons...

While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations of approx. 1%. Extended studies and theories on non-spherical particles in simple fluids find a more complicated behavior, but still a steady increase with increasing concentration. Involving plat...

Drug loaded polymer micelles or nanoparticles are being continuously explored in the fields of drug delivery and nanomedicine. Commonly, a simple core-shell structure is assumed, in which the core incorporates the drug and the corona provides steric shielding, colloidal stability, and prevents protein adsorption. Recently, the interactions of the d...

Neutron spin echo spectroscopy has been used under grazing incidence conditions to study the dynamics of SoyPC phospholipid membranes at the solid-liquid interface. The use of advanced neutron optical components such as a neutron prism and a resonator structure at the interface for an increase in intensity near the interface helped to study partial...

Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs or many types of biological macromolecules, including DNA and proteins. Efficiency and speed of cargo delivery are especially high for carrier vesicles that fuse with the cellular plasma membrane. This occurs for lipid mixture containing equal amounts of...

We investigated the existence of long-range excitations and correlated structures in phospholipid membranes by means of grazing-incidence neutron spin echo spectroscopy, grazing-incidence small-angle neutron scattering, and corresponding theoretical calculations inspired by smectic-membrane theory. All these methods confirmed the existence of therm...

Investigating lateral structures of surfaces and interfaces from the mesoscale down to atomic resolution is of growing interest to modify, functionalize, and understand the behavior of materials in soft matter and biophysics. Grazing-incidence scattering techniques have proven to be very powerful for such kind of studies. Using X-rays and neutrons...

The response of a position-sensitive Li-glass scintillator detector to α-particles from a collimated ²⁴¹ Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 × 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel...

Small-Angle Scattering (SAS) investigates structures in samples that generally range from approximately 0.5 nm to a few 100 nm. This can both be done for isotropic samples such as blends and liquids, as well as anisotropic samples such as quasi-crystals. In order to obtain data about that size regime scattered intensity, mostly of x-rays or neutron...

The response of a position-sensitive Li-glass scintillator detector to alpha-particles from a collimated 241Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 X 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pi...

In this manuscript, we are investigating the contribution of dynamic membrane properties of phospholipid membranes to coherent scattering signals under grazing incidence. Spectroscopic measurements under grazing incidence can provide useful insight into the properties of biological membranes; however, they are often impeded by weak signals. By usin...

Building the European Spallation Source (ESS), the most powerful neutron source in the world, requires significant technological advances at most fronts of instrument component design. Detectors are not an exception. The existing implementations at current neutron scattering facilities are at their performance limits and sometimes barely cover the...

In this manuscript we are investigating the contribution of dynamic membrane properties of phospholipid membranes to coherent scattering signals under grazing incidence. Spectroscopic measurements under grazing incidence can provide useful insight into the properties of biological membranes, however are often impeded by weak signals. By using grazi...

Building the European Spallation Source (ESS), the most powerful neutron source in the world, requires significant technological advances at most fronts of instrument component design. Detectors are not an exception. The existing implementations at current neutron scattering facilities are at their performance limits and sometimes barely cover the...

During this experiment we were testing the hypothesis that standing waves in a phospholipid membrane stack indeed lead to a detectable signal in coherent grazing-incidence small-angle neutron scattering, GISANS. These modes were identified earlier in a previous experiment using grazing-incidence neutron spin-echo spectroscopy, GINSES, (Jaksch, S.,...

Using grazing incidence scattering methods allows for depth profiling near surface structures very efficiently Dosch (1986). In parallel, layered structures have been used as resonators to enhance the wave field Kozhevnikov et al. (2007), Khaydukov et al. (2011), Kozhevnikov et al. (2011) and Nesnidal and Walker (1996) that directly increases the s...

This are the cumulated reports of the SoNDe detector Project as of July 2017. The contained reports are: - Report on the 1x1 module technical demonstrator - Report on used materials - Report on radiation hardness of components - Report on potential additional applications - Report on the 2x2 module technical demonstrator - Report on test results of...

Here we present an approach to measure dynamic membrane properties of phospholipid membranes close to an interface. As an example we show results of the membrane dynamics of a phospholipid membrane multilayer-stack on a solid substrate (silicon). On this sample we were able to measure local interaction and friction parameters using Grazing Incidenc...

Biocompatible polymers that form thermoreversible supramolecular hydrogels have gained great interest in biomaterials research and tissue engineering. When favorable rheological properties are achieved at the same time, they are particularly promising candidates as material that allow for the printing of cells, so-called bioinks. We synthesized a n...

Nanoparticles play an important role in controlling the mobility of pollutants such as arsenic (As) in the environment. In natural waters, aggregates of nanoparticles can be constituted of organic matter (OM) associated with iron (Fe). However, little is known about their network structure, especially the role of each component in the resulting agg...

Back Cover: Amphiphilic triblock copolymers from poly(2-oxazoline)s solubilize huge amounts of the strongly hydrophobic cancer drug paclitaxel. Small-angle neutron scattering revealed a possible reason: Paclitaxel forms small domains which are not only located within the micellar core but also at the interface between the core and the shell of the...

In any neutron scattering experiment the measurement of the position of the scattered neutrons and their respective velocities is necessary. In order to do so, a position sensitive detector as well as a way to determine the velocities is needed. Measuring the velocities can either be done by using only a single wavelength and therefore velocity or...

Following the introduction of the program DENFERT [Koutsioubas & Pérez (2013). J. Appl. Cryst.46, 1884–1888], which takes into account the hydration layer around solvated biological molecules during ab initio restorations of low-resolution molecular envelopes from small-angle X-ray scattering data, the present work introduces the second version of...

Amphiphilic triblock copolymers with poly(2-methyl-2-oxazoline) (MeOx) end blocks and a poly(2-n-butyl-2-oxazoline) (nBuOx) middle block have been found to solubilize large amounts of the cancer drug paclitaxel (PTX) whereas this is not the case when the middle block is more hydrophobic, such as poly(2-n-nonyl-2-oxazoline) (NOx) (Schulz et al., ACS...

One problem of non-crystalline condensed matter (soft matter) is creating the right equilibrium between elasticity and viscosity, referred to as viscoelasticity. Manifestations of that can be found in everyday live, where the viscoelasticity in a tire needs to be balanced so it is still flexible and can dissipate shock-energy, yet hard enough for e...

The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Jülich Centre for Neutron Science (JCNS) at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. The KWS-1 instrument was updated, from its active collimation apertures to the detector cabling. Most of the parts...

We investigate the conformational properties of stimuliresponsive hydrogels from triblock polyelectrolytes PtBA-b-P2VP-b-PtBA (PtBA and P2VP are poly(tert-butyl acrylate) and poly(2-vinylpyridine)) and the corresponding polyampholytes PAA-b-P2VP-b-PAA (PAA is poly(acrylic acid)), the latter with nonquaternized or quaternized P2VP blocks. The block...

We investigate the cononsolvency effect of poly(N-isopropylacrylamide) (PNIPAM) in mixtures of water and methanol. Two systems are studied: micellar solutions of polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) diblock copolymers and, as a reference, solutions of PNIPAM homopolymers, both at a concentration of 20 mg/mL in D2O. Using a stoppe...

The nanostructures of thin films spin-coated from binary blends of compositionally symmetric polystyrene-b-polybutadiene (PS-b-PB) diblock copolymer having different molar masses are investigated by means of atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GISAXS) after spin-coating and after subsequent solvent vapo...

The reorientation of lamellae and the dependence of the lamellar spacing, D lam, on polymer volume fraction, ϕP, D lam ∝ ϕP (-β), in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming...

We have investigated the collapse transition of aqueous solutions of gradient copolymers from poly(iso-propyl-2-oxazoline)s (PiPrOx), which contain few hydrophobic moieties (n-nonyl-2-oxazoline (NOx) monomers). We extend our previous investigations (Salzinger et al., Colloid Polym Sci 290:385–400, 2012), where, for the gradient copolymers, an inter...

Basic understanding of biological membranes is of paramount importance as these membranes comprise the very building blocks of life itself. Cells depend in their function on a range of properties of the membrane, which are important for the stability and function of the cell, information and nutrient transport, waste disposal and finally the admiss...

A new Small Angle Neutron Scattering instrument is proposed for the European Spallation Source. The pulsed source requires a time-of-flight analysis of the gathered neutrons at the detector. The optimal instrument length is found to be rather large, which allows for a polarizer and a versatile collimation. The polarizer allows for studying magnetic...

Defined aggregates of polymers such as polymeric micelles are of great importance in the development of pharmaceutical formulations. The amount of drug that can be formulated by a drug delivery system is an important issue and most drug-delivery systems suffer from their relatively low drug loading capacity. However, as the loading capacities incre...

The goal of this thesis is to investigate the solution behavior of poly(2-oxazoline) (POx) based aqueous polymer solutions by small-angle neutron scattering and dynamic light scattering. In the case of thermoresponsive POx an intermediate regime above the cloud point (CP) is found, where small aggregates, formed already at temperatures below the CP...

We have studied different thermo-responsive poly(2-oxazoline)s with iso-propyl (iPrOx) and n-propyl (nPrOx) pendant groups in aqueous solutions, where they exhibit LCST behavior. This paper focuses on the effect of the degree of polymerization, n, the concentration, c, in the dilute regime, and the presence of hydrophobic moieties. The cloud points...

We report on the temperature dependence of the nanostructure of thin block copolymer films, as studied using in situ grazing-incidence small-angle x-ray scattering (GISAXS). We focus on spin-coated poly(styrene-b-butadiene) diblock copolymer thin films featuring lamellae perpendicular to the substrate. In situ GISAXS measurements elucidate the stru...

Water in oil microemulsions, consisting of water, AOT and n-decane, have been used as a model system to investigate the influence of the water soluble polymer PEO on the dynamical behavior of the system. Therefore dielectric relaxation spectroscopy and conductivity, extracted from dielectric spectroscopy, measurements in a wide frequency and temper...