Filtyp
We report small-angle scattering experiments with two different types of model proteins, lysozyme and the eye lens protein γB-crystallin. We discuss the results in the context of recent suggestions that globular proteins possess a short-ranged attractive potential, and that simple models from colloid science could help to rationalize the best route for obtaining protein crystals and to interpret t
Colloidal liquids usually appear turbid due to the strong multiple scattering of electromagnetic waves from the particles in suspension. As the concentration increases, particle interactions induce positional correlations which generally lead to a reduced optical density (higher transparency). However, the optical properties of a colloidal liquid can be manipulated by tuning the interaction potent
Controlling interparticle interactions, aggregation and cluster formation is of central importance in a number of areas, ranging from cluster formation in various disease processes to protein crystallography and the production of photonic crystals. Recent developments in the description of the interaction of colloidal particles with short-range attractive potentials have led to interesting finding
We have studied various complex systems from particle and biopolymer gels to concentrated surfactant solutions using classical rheometry and optical microrheology. Optical microrheology uses dynamic light scattering, usually in the multiple scattering regime, to obtain information about the microscopic dynamic properties of complex media. This can be done either by direct investigation or by addit
We have studied the dynamical and structural properties of destabilized nanoparticle suspensions by a combination of small-angle neutron scattering (SANS) and diffusing wave spectroscopy (DWS). SANS and DWS provide structural and dynamic information about opaque samples online during the gelation process. With our new experimental setup we access a broad range of length and time scales perfectly s
Hydrous ferric oxides (HFO) are efficient sorbents for inorganic and organic pollutants and therefore have great potentials in environmental science and engineering applications. Freezing and thawing of HFO suspensions leads to the formation of dense HFO aggregates. It facilitates the handling and increases the drying rate of HFO. In this study, we used a combination of pycnometry, gas adsorption
We present results from a study of the structural properties of concentrated lens protein solutions using small-angle neutron and X-ray scattering. The lens proteins are particularly interesting and important, as they are ideally suited for an attempt to use well-defined and monodisperse proteins as model systems for colloids as well as because of their biological and medical relevance for catarac
A new sample environment has been developed in order to perform light and small-angle neutron scattering (SANS) simultaneously on colloidal systems. The combination of SANS and diffusing wave spectroscopy (DWS) is of particular use in the high-concentration regime. DWS provides information on the local dynamic properties of the individual particles, whereas SANS gives access to the structural prop
We have studied the dynamical and structural properties of dense charge stabilized colloidal suspensions by a combination of small-angle neutron scattering (SANS), 3D dynamic light scattering (3DDLS) and diffusing wave spectroscopy (DWS). SANS and 3DDLS extend static and dynamic light scattering techniques to the regime of opaque samples while DWS additionally provides information on short length
We show that diffusing wave spectroscopy (DWS) permits the characterization of dynamic properties of concentrated colloidal suspensions on a large range of time- and length-scales ranging from a few angstroms to tens of nanometres. We focus in particular on the study of the aggregation and sol-gel transition in concentrated colloidal suspensions. We present a new technique to overcome the problem
The application of light scattering to concentrated colloidal suspensions has often been considered too complicated due to strong multiple scattering. Here we show that diffusing wave spectroscopy (DWS) permits the characterization of dynamic and static properties of such systems on a large range of time and length scales. In particular we focus on the aggregation and sol-gel transition in differe
We report an investigation of the microscopic structure and dynamics of biopolymer gels and relate them to the macroscopic viscoelastic properties of such systems. Biopolymer solutions and gels represent one of the most interesting class of gelling systems since they are of major industrial and scientific interest. We performed a systematic study using concentrated solutions of casein micelles whi
Surfactants containing sugar components and fatty acids satisfy the quality standards for food application. The food grade sugar ester in this study is a commercial sucrose monoester of stearic acid (abbreviated SES), the oil phase consists of a 1:1 mixture of n-tetradecane and l-butanol. The originally planned food grade oil, a medium chain triglyceride, is substituted by tetradecane because tetr
Sugar surfactants have recently attracted considerable interest. We report systematic light and neutron scattering experiments with aqueous solutions of the alkyl polyglucoside C8/10G1.5. The system exhibits a transition from globular to polymer-like micelles upon adding hexanol. We can finely tune the extent of micellar growth and reach conditions where solutions of relatively short cylinders exi
Sugar surfactants have recently attracted considerable interest. Here we report a systematic light and neutron scattering investigation of aqueous solutions of the alkyl polyglucoside C8/10G1.5. The system exhibits a transition from globular to giant wormlike micelles upon the addition of hexanol. We can finely tune the extent of micellar growth and in particular reach conditions where solutions o
We used fluorogenic substrates, namely, alkyldiacyl glycerols labeled with a fluorophore and a fluorescence quencher, to measure lipase activities. For this optical lipase assay it is necessary that the water-insoluble fluorogenic substrates are dispersed in an aqueous medium in the presence of appropriate detergents in order to obtain well-defined and reproducible systems with high optical transp
Vesicle and micellar structures formed by mixtures of the oppositely charged surfactants cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) with and without added sodium bromide (NaBr) have been examined by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques. The resulting spectra have been evaluated using a Fourier transform/deconvolution tec
Entangled photons offer quantum correlations with no classical analogue. In entangled pair two-photon absorption (ETPA), absorption rate is predicted to scale linearly rather than quadratically with photon flux, promising molecular excitation at fluxes far below the classical threshold. Reported ETPA cross sections nevertheless vary widely across experiments, largely since the observable, the diff
For the 2027 State Garden Show (LGS) in Neustadt a. d. WeinstraBe, a building will be erected, using a CEM II/C-M (Q-LL) as binder containing 30 O/o calcined clay in combination with 15 O/o limestone powder and just 55 O/o clinker (incl. sulphate carrier), for the first time in Germany. The panorama bar on the Neustadt viewpoint is a single-story building in reinforced concrete construction with a
Mechanochemical activation (MCA) of phyllosilicates is one of the most promising solutions to produce reactive supplementary cementitious materials (SCMs). Several studies have already shown that MCA outperforms thermal activation (TA) in terms of reactivity when clays are low in kaolinite but rich in 2:1 phyllosilicates. Because reactivity depends on phyllosilicate type as well as content, and cl
