Impaired working memory is a core feature of schizophrenia and is linked with altered engagement the lateral prefrontal cortex. Although altered PFC activation has been reported in people with increased risk of psychosis, at present it is not clear if this neurofunctional alteration differs between familial and clinical risk states and/or increases in line with the level of psychosis risk. We addressed this issue by using functional MRI and a working memory paradigm to study familial and clinical high-risk groups. We recruited 17 subjects at ultra-high-risk (UHR) for psychosis, 10 non-affected siblings of patients with schizophrenia (familial high risk [FHR]) and 15 healthy controls. Subjects were scanned while performing the N-back working memory task. There was a relationship between the level of task-related deactivation in the medial PFC and precuneus and the level of psychosis risk, with deactivation weakest in the UHR group, greatest in healthy controls, and at an intermediate level in the FHR group. In the high-risk groups, activation in the precuneus was associated with the level of negative symptoms. These data suggest that increased vulnerability to psychosis is associated with a failure to deactivate in the medial PFC and precuneus during a working memory task, and appears to be most evident in subjects at clinical, as opposed to familial high risk.

Micro-X-ray fluorescence (μ-XRF) is a rapidly evolving analytical technique which allows visualising the trace level metal distributions within a specimen in an essentially nondestructive manner. At second generation synchrotron radiation sources, detection limits at the sub-parts per million level can be obtained with micrometer resolution, while at third generation sources the spatial resolution can be better than 100 nm. Consequently, the analysis of metals within biological systems using micro- and nano-X-ray fluorescence imaging is a quickly developing field of research. Since X-ray fluorescence is a scanning technique, the elemental distribution within the sample should not change during analysis. Biological samples pose challenges in this context due to their high water content. A dehydration procedure is commonly used for sample preparation enabling an analysis of the sample under ambient temperature conditions. Unfortunately, a potential change in elemental redistribution during the sample preparation is difficult to verify experimentally and therefore cannot be excluded completely. Creating a cryogenic sample environment allowing an analysis of the sample under cryogenic condition is an attractive alternative but not available on a routine basis. In this article, we make a comparison between the elemental distributions obtained by micro-SR-XRF within a chemically fixed and a cryogenically frozen Daphnia magna, a model organism to study the environmental impact of metals. In what follows, we explore the potential of a dual detector setup for investigating a full ecotoxicological experiment. Next to conventional 2D analysis, dual detector X-ray fluorescence cryotomography is illustrated and the potential of its coupling with laboratory absorption micro-CT for investigating the tissue-specific elemental distributions within this model organism is highlighted.

Sauropod dinosaurs were typically one magnitude larger than any other living or extinct terrestrial animal. This sheer size of the sauropod leads to scale effects in their biology and physiology that still are inadequately understood. The only remnants of the sauropods are their fossilized bones. These fossilized bones have sustained burial for some hundred million years and thus may have experienced significant diagenetic changes. These diagenetic changes often do not affect bone preservation on the histological level, but may lead to significant alterations of the bone microstructure. Here the influence of diagenesis on the microstructure of fossilized sauropod bones using femur cross section of Brachiosaurus brancai that was excavated in the Tendaguru beds in Tanzania is investigated. The element distribution in this dinosaur bone is studied by a combination of micro-X-ray-fluorescence (μ-XRF) using synchrotron radiation and energy dispersive X-ray analyses (EDX) in the scanning electron microscope. These techniques reveal quantitative values of the element concentration at a macroscopic level combined with qualitative information at high spatial resolution of the distribution of Ca, Co, Cr, V, Pb, U, Sr, Y, and As in the fossil bones. This allows a differentiation between the remnants of the original bone apatite and pore filling minerals and also a visualization of damage, e.g., cracks introduced by diagenetic processes.

Synchrotron-based X-ray techniques are used increasingly to characterize actinide element speciation in heterogeneous media related to nuclear waste disposal safety. Especially techniques offering added temporal, spatial and energy resolved information are advancing our understanding of f-element physics and chemistry in general and of actinide element waste disposal in particular. Examples of investigations of uranium containing systems using both highly (energy) resolved X-ray emission spectroscopy (HRXES) techniques and spatially resolved techniques with focused X-ray beams are presented in this paper: polarization dependent partial fluorescence yield X-ray absorption near edge structure (PD-PFY-XANES) spectroscopic studies of a single Cs2UO2Cl4 crystal, which experimentally reveal a splitting of the σ, π, and δ components of the 6d valence states [1], and characterization of UO2/Mo thin films prepared on different substrates using a combination of techniques (2D and 3D micro- and nano-X-ray fluorescence, XANES and both holographic and ptychographic tomography).

Until recently there has been very limited information concerning the molecular geometry and conformation of biogenic monoamines and this lack of knowledge has seriously hampered efforts to unravel the structure—function relationships at the molecular level. Nevertheless, several theories have been proposed regarding interaction between the monoamines and their receptor sites. This is especially true for the neurohumoral transmitters dopamine, noradrenaline (norepinephrine) and serotonin (5-hydroxytryptamine), the target areas of which seem to be specific not only in the sense of chemical structure but also from the steric point of view. The well-known differences in biological activity due to chiralty illustrate the importance of the three-dimensional architecture of the molecules and indicate also the presence of stereospecific receptor sites. A detailed knowledge of the conformation of the biogenic monoamines would not only elucidate the requirements upon a natural or synthetic monoamine for proper function but also give indirect information about the geometry of the receptor sites.

A fundamental study focusing on correlating the local water self-diffusion coefficient to the local free water content in 2-hydroxyethyl methacrylate (HEMA) gels was conducted. HEMA gels were synthesized with different nominal water content (50% to 90%). MRI measurements of local diffusion coefficient distribution and local water content profiles are conducted on a 600 MHz scanner. The local water content is measured via two spin-echo images with sufficiently long repetition time (TR) to eliminate T1-weighting and two values for the echo time (TE) in order to account for T2-weighting. The local diffusion coefficient is determined using a standard pulsed-field gradient spin-echo sequence. The measured local water content and diffusion coefficient data are compared with several single-parameter diffusion models for interstitial diffusion in the hydrogel (Makie-Meares, Stokes-Einstein, Brownian motion around overlapping spheres).

Rare earth-, transition metal- and metal doped soda lime-, BK7- and photosensitive lithium aluminosilicate glass are irradiated by pulsed UV laser radiation (wavelength λL = 355nm, pulse length tp = 10 to 80 ns) as a function of repetition rate, pulse energy and overlap between successive pulses. The solid state laser radiation is focused into the volume to fluences below the removal-threshold. Depending on the chemical composition, the laser parameters, and the processing variables the laser radiation is absorbed by optically- and photochemically active polyvalent ions with conversion of the optical energy into fluorescence stimulation and ionization as well as color center formation resulting in modifications and/or color markings in the VIS. The absorption and concentration changes of the polyvalent ions are probed by optical spectroscopy and transient absorption spectroscopy. The photochemical and -physical processes such as oxidation and reduction of polyvalent ions and/or color center generation underlying the modifications and color markings are discussed.