Delirium in neurosurgery: a systematic review and meta-analysis.

Delirium is a frequent occurring complication in surgical patients. Nevertheless, a scientific work-up of the clinical relevance of delirium after intracranial surgery is lacking. We conducted a systematic review (CRD42020166656) to evaluate the current diagnostic work-up, incidence, risk factors and health outcomes of delirium in this population. Five databases (Embase, Medline, Web of Science, PsycINFO, Cochrane Central) were searched from inception through March 31st, 2021. Twenty-four studies (5589 patients) were included for qualitative analysis and twenty-one studies for quantitative analysis (5083 patients). Validated delirium screening tools were used in 70% of the studies, consisting of the Confusion Assessment Method (intensive care unit) (45%), Delirium Observation Screening Scale (5%), Intensive Care Delirium Screening Checklist (10%), Neelon and Champagne Confusion Scale (5%) and Nursing Delirium Screening Scale (5%). Incidence of post-operative delirium after intracranial surgery was 19%, ranging from 12 to 26% caused by variation in clinical features and delirium assessment methods. Meta-regression for age and gender did not show a correlation with delirium. We present an overview of risk factors and health outcomes associated with the onset of delirium. Our review highlights the need of future research on delirium in neurosurgery, which should focus on optimizing diagnosis and assessing prognostic significance and management.

Antimony leaching and chemical species analyses in an industrial solid waste: Surface and bulk speciation using ToF-SIMS and XANES.

The surface chemistry and bulk chemical speciation of solid industrial wastes containing 8wt-% antimony (Sb) were investigated using synchrotron X-ray Absorption Near Edge Structure (XANES) and Time-of-Flight Ion Secondary Mass Spectrometry (ToF-SIMS). Leaching experiments were conducted in order to better understand the behavior of Sb in waste streams and to inform regulatory management of antimony-containing wastes. The experiments also demonstrate how a combination of XANES and ToF-SIMS adds value to the field of waste investigations. Leaching treatments (acid and base) were performed at a synchrotron over 24h time periods. Surface analyses of the wastes before leaching showed the presence of Sb associated with S and O. Bulk analyses revealed Sb to be present, primarily, as trivalent sulfide species. Both acid and base leaching did not change the antimony speciation on the solid. Leaching transferred about 1% of the total Sb into solution where Sb was found to be present as Sb(V). XANES data showed similarities between leachate and FeSbO4. During base leaching, the Sb content in solution gradually increased over time, and potential desorption mechanisms are discussed.

Arsenic solid-phase speciation and reversible binding in long-term contaminated soils.

Historic arsenic contamination of soils occurs throughout the world from mining, industrial and agricultural activities. In Australia, the control of cattle ticks using arsenicals from the late 19th to mid 20th century has led to some 1600 contaminated sites in northern New South Wales. The effect of aging in As-mobility in two dip-site soil types, ferralitic and sandy soils, are investigated utilizing isotopic exchange techniques, and synchrotron X-ray adsorption spectroscopy (XAS). Findings show that historic soil arsenic is highly bound to the soils with >90% irreversibly bound. However, freshly added As (either added to historically loaded soils or pristine soils) has a significantly higher degree of As-accessibility. XAS data indicates that historic soil arsenic is dominated as Ca- (svenekite, & weilite), Al-(mansfieldite), and Fe- (scorodite) like mineral precipitates, whereas freshly added As is dominated by mineral adsorption surfaces, particularly the iron oxy-hydroxides (goethite and hematite), but also gibbsite and kaolin surfaces. SEM data further confirmed the presence of scorodite and mansfieldite formation in the historic contaminated soils. These data suggest that aging of historic soil-As has allowed neoformational mineral recrystallisation from surface sorption processes, which greatly reduces As-mobility and accessibility.

Speciation and lability of Ag-, AgCl-, and Ag2S-nanoparticles in soil determined by X-ray absorption spectroscopy and diffusive gradients in thin films.

Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-), and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-DGT devices were designed specifically to avoid confounding effects when measuring element lability in the presence of nanoparticles. The aging profile and stabilities of the three nanoparticles and AgNO3 (ionic Ag) in soil were examined at three different soil pH values over a period of up to 7 months. Transformation of ionic Ag, Ag-NP and AgCl-NPs were dependent on pH. AgCl formation and persistence was observed under acidic conditions, whereas sulfur-bound forms of Ag dominated in neutral to alkaline soils. Ag2S-NPs were found to be very stable under all conditions tested and remained sulfur bound after 7 months of incubation. Ag lability was characteristically low in soils containing Ag2S-NPs. Other forms of Ag were linked to higher DGT-determined lability, and this varied as a function of aging and related speciation changes as determined by XAS. These results clearly indicate that Ag2S-NPs, which are the most environmentally relevant form of Ag that enter soils, are chemically stable and have profoundly low Ag lability over extended periods. This may minimize the long-term risks of Ag toxicity in the soil environment.

Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil.

This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography∕diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

A coherence approach to phase-contrast microscopy II: experiment.

We report an experimental investigation of the optical transfer functions for an X-ray microscope operated in defocus phase-contrast mode. The results are compared with a theoretical model of partially coherent image formation and are found to be in excellent agreement.

Addition of carboxylic acids modifies phosphate sorption on soil and boehmite surfaces: a solution chemistry and XANES spectroscopy study.

Soil acidification is a globally significant agricultural issue, as the plant availability of phosphorus (P) is decreased through increased P sorption onto aluminium (Al) hydroxides and other solid phase binding sites. X-ray absorption near edge structure (XANES) spectroscopy generated new information on the speciation of Al and P in the presence of carboxylic acids on soil and boehmite (gamma-AlOOH) surfaces. XANES spectra were acquired in the soft X-ray regime at the P and Al L(2,3)-edges, and the Al K-edge, respectively. Adding oxalic acid to soil enhanced Al dissolution and exposed previously occluded soil P, while hydroxybenzoic and coumaric acids did not compete with P for surface binding sites. Boehmite strongly adsorbed carboxylic acids in the absence of applied phosphorus. However, when P was applied with carboxylic acids, the carboxylics were unable to compete with P for binding, especially hydroxybenzoic and coumaric acids. Using XANES in both total electron yield and fluorescence yield modes provided valuable information on both surface and near-surface processes of P and Al due to different information depths. The Al K-edge XANES provided baseline information on the solid-phase matrix. XANES in total electron yield mode and at the P L-edge shows promise for speciation of elements on soil surfaces due to enhanced sensitivity for speciation of surface-adsorbed species compared to the commonly used P K-edge XANES.

Time-resolved XANES speciation studies of chromium on soils during simulated contamination.

Time-resolved synchrotron X-ray absorption near edge structure (XANES) spectroscopy was used to study changes of chromium speciation in soils upon soil-water interaction. The time resolution was 30-45 min. In a flow-column apparatus operated near the synchrotron beamline, two different types of soil were treated with potassium-dichromate solution, and soil samples were taken and directly analysed by XANES. The results provide insight into different equilibrium times of a few hours, depending on the type of soil. The XANES speciation analyses, based on a model comprising insoluble Cr(III) and Cr(VI) compounds, show how the fate of Cr species on soils can be followed close to real-time. Since the method allowed the soils to be investigated close to real-time, sampling in the field and preservation before analysis were made redundant. This study benefits the development of corresponding in situ remediation techniques.

Measurements of photon interference X-ray absorption fine structure (piXAFS).

Experimental data are presented which demonstrate the existence of a fine structure in extended X-ray absorption spectra due to interference effects in the initial photon state (piXAFS). Interference occurs between the incident electromagnetic wave and its coherently scattered waves from neighboring atoms. Using fine platinum and tungsten powders as well as polycrystalline platinum foil, piXAFS was measured in high-precision absorption experiments at beamline X1 at HASYLAB/DESY over a wide energy range. piXAFS is observed below and above absorption-edge positions in both transmission and total-electron-yield detection. Based on experimental data it is shown that piXAFS is sensitive to geometric atomic structure. Fourier-transformed piXAFS data carry information, comparable with that of EXAFS, about the short-range-order structure of the sample. Sharp structures occur in piXAFS when a Bragg backscattering condition of the incident X-rays is fulfilled. They allow precise measurement of long-range-order structural information. Measured data are compared with simulations based on piXAFS theory. Although piXAFS structures are similarly observed in two detection techniques, the importance of scattering off the sample for the measurements needs to be investigated further. Disentangling piXAFS, multielectron photoexcitations and atomic XAFS in high-precision measurements close to absorption edges poses a challenge for future studies.

Fluorescence EXAFS for the in situ study on the state of promoters in catalysis.

The fluorescence EXAFS (FLEXAFS) technique has been combined with an in situ cell and on-line gas analysis. For this purpose a seven-element silicon drift detector has been used, which has high count rate capabilities and can be operated at room temperature. The potential of this technique is shown by the study of the state of copper promoter atoms in Fe-Cr based high temperature shift (HTS) catalysts. The FLEXAFS measurements revealed that Cu (0.17-1.5 wt%) is present in the metallic state under working conditions of the catalysts but easily re-oxidizes upon air exposure. The reduction behaviour of copper depends strongly on the copper concentration and the pre-treatment, i.e. if the catalysts have been calcined or used in the HTS reaction. For used catalysts, a Cu(I) phase was detected as intermediate during reduction. Its stability was especially high at low copper concentration.