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We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-A wavelength with pulse energies of more than 500 μJ, pulse durations of ~30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of ~2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation. The first lasing results at SwissFEL, an X-ray free-electron laser, are presented, highlighting the facility’s unique capabilities. A general comparison to other major facilities is also provided.

In this paper, we present a soft x-ray variable line-spacing spherical grating monochromator, which is shared between the three ATHOS beamlines at SwissFEL. The instrument uses grazing incidence angles of less than 3° to withstand the peak-fluence of femtosecond FEL pulses with energies up to 8 mJ. The upward facing monochromator grating facilitates endstations with different beam heights. We explain the integration of the monochromator into the beamlines; discuss its mechanical design, its control system and its optical components. We conclude with showing an initial calibration spectrum and detail the currently achieved performance.

International audience; The Bernina instrument at the SwissFEL Aramis hard X-ray free-electron laser is designed for studying ultrafast phenomena in condensed matter and material science. Ultrashort pulses from an optical laser system covering a large wavelength range can be used to generate specific non-equilibrium states, whose subsequent temporal evolution can be probed by selective X-ray scattering techniques in the range 2–12 keV. For that purpose, the X-ray beamline is equipped with optical elements which tailor the X-ray beam size and energy, as well as with pulse-to-pulse diagnostics that monitor the X-ray pulse intensity, position, as well as its spectral and temporal properties. The experiments can be performed using multiple interchangeable endstations differing in specialization, diffractometer and X-ray analyser configuration and load capacity for specialized sample environment. After testing the instrument in a series of pilot experiments in 2018, regular user operation begins in 2019.

The development of visible-light-mediated allylation of unactivated sp3 C-H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre-functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C-H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ-carbon radical acceptor.

Detection of single-base mismatches with respect to a probe strand has been a predominant pursuit in electrochemical biosensor efforts, due to links found between single nucleotide polymorphisms (SNPs) and the predisposition to various diseases. We report an osmium tetroxide bipyridine-based, thermally-controlled, competitive-strand electrochemical assay to allow amplified detection of single-base mismatches. Optimally designed competitive-strand displacement and hybridization temperature allows us to distinguish the single-mismatched-target from the fully complementary sequence with unambiguous, highly reproducible, robust signal differences of over 90%. Furthermore, we find a complex interplay between the position of the redox label, variations in strand displacement kinetics due to mismatches incorporated into the competitive strand, and alterations in the melting temperature of DNA duplexes tethered on the gold surface, when probed by square-wave voltammetry. These insights will apply to any surface-tethered DNA-based electrochemical biosensor, and can help with understanding complex phenomena involved in these types of assays.

Summary Heated electrodes have been introduced a few decades ago to perform thermoelectrochemical investigations in a very flexible manner. This review considers unusual materials and devices that have been introduced recently to create new heated and also actively cooled electrodes: carbon paste with ionic liquids as binder, carbon nanotubes, iridium, Hg films, Bi films, Bi–Au alloys, gold nanostructures, and indium-doped tin oxide. Scanning electrochemical microscopy (SECM) based on thermocouple tips, as well as SECM of heated electrode arrays, and hot-tip-SECM have been proposed to study surfaces. Thermo-responsive layers allow for rapid switching of heated electrode surfaces. Recent years have seen a broad variety of thermoelectrochemical studies enabled by actively heated and cooled electrodes based on new materials. Very quick temperature changes and very high energy efficiency are two very distinct advantages of directly heated electrodes over both isothermal electrochemical cells and indirectly heated electrodes that suffer from high heat capacity.

We report the development of a “sandwich-hybridization” electrochemical DNA-detection assay on gold electrodes using osmium tetroxide-labeled reporter strands, while avoiding chemical modification of analyte strands. Successful design of the oligonucleotides used in the assay required a significant adjustment to solution-based estimates of melting temperature for the immobilized-probe/target duplex, to achieve optimal displacement kinetics. This allowed for reduced hybridization times and temperatures, and a higher sensitivity at low concentrations of DNA-analyte than oligos designed using solution-based melting temperatures as a guide. In addition we found that for the highest ranges of probe surface-density, signal response was sluggish until the DNA self-assembled monolayer (SAM) was exposed to several hybridization procedures, suggesting a modification of the SAM in response to a hybridization experiment. Use of a less-dense SAM eliminated this effect, suggesting increased influence of molecular crowding on the sandwich assay versus a simple hybridization. The high sensitivity, quick response time, relative simplicity and low cost demonstrated here helps pave the way for a field-level electrochemical genetic sensor using our method, as the unmodified target from samples in question can be tested directly without a chemical labeling step.

Joule-heated electrodes have been used to enhance electrochemical analysis. Due to such direct heating, a steep temperature gradient is created near the electrode surface. The heating device that provides the high-frequency AC (50 kHz or more) has to be calibrated, in order to apply the desired temperature during analysis. The applied temperature of the working electrode influences both its electrical resistance and the electrochemical potential of a redox couple. Open circuit potentiometric (OCP) measurements were performed automatically with screen-printed gold loop electrodes (Au-LE), while applying 50 kHz AC heating pulses of increasing intensity provided by a ThermaLab® AC generator. Potentiometric temperature calibrations were performed using 5 mM equimolar ferri/ferrocyanide in 0.1 M of potassium chloride at 20 °C bulk temperature. Potential differences produced during each heat pulse were used to automatically calculate the electrode temperature using the temperature coefficient of this redox couple (-1.6 mV/K). The electrode resistance values at each heating pulse were obtained by measuring the heating voltage and heating current. The automatic temperature calibration experiments with five Au-LEs were shown to be highly reproducible and precise, with an RSD for the temperature of 0.24% and 4% for resistance. The average margin error of OCP temperatures were ±0.66 K at a 95% confidence level. The temperature coefficient (α) of electrical resistivity of the screen-printed gold layers was found to be 0.0025 °C-1, which is 27% lower than the theoretical value for gold metal. These findings were confirmed by DC resistance measurements using a potentiostat. Comparing the OCP temperature with the resistivity method, the temperature difference was about 0.94 °C (2.8%). Both methods enable quick, reproducible and accurate temperature calibration for disposable Au-LE, which were also used for trace mercury detection in lake water samples

The extension of transient grating spectroscopy to the x-ray regime will create numerous opportunities, ranging from the study of thermal transport in the ballistic regime to charge, spin, and energy transfer processes with atomic spatial and femtosecond temporal resolution. Studies involving complicated split-and-delay lines have not yet been successful in achieving this goal. Here we propose a novel, simple method based on the Talbot effect for converging beams, which can easily be implemented at current x-ray free electron lasers. We validate our proposal by analyzing printed interference patterns on polymethyl methacrylate and gold samples using similar to 3 keV X-ray pulses. (C) 2019 Optical Society of America

The two Aramis beamlines at SwissFEL are currently under commissioning, first pilot experiments have already been carried out. In total we have 10 mirror systems, 6 offset mirrors and 4 mirrors in KB [1] configuration. We use bilayer mirror coatings to handle the single shot damage challenge at FELs. The optics has to keep the coherence of the FEL pulses. We use flat mirrors with figure errors on the single nm level in two-actuator mechanical bender systems. The vertically deflecting KB mirrors have a polished-in gravity sag compensation. The performance of the mirror systems has been verified with X-rays.

The SwissFEL soft X-ray free-electron laser (FEL) beamline Athos will be ready for user operation in 2021. Its design includes a novel layout of alternating magnetic chicanes and short undulator segments. Together with the APPLE X architecture of undulators, the Athos branch can be operated in different modes producing FEL beams with unique characteristics ranging from attosecond pulse length to high-power modes. Further space has been reserved for upgrades including modulators and an external seeding laser for better timing control. All of these schemes rely on state-of-the-art technologies described in this overview. The optical transport line distributing the FEL beam to the experimental stations was designed with the whole range of beam parameters in mind. Currently two experimental stations, one for condensed matter and quantum materials research and a second one for atomic, molecular and optical physics, chemical sciences and ultrafast single-particle imaging, are being laid out such that they can profit from the unique soft X-ray pulses produced in the Athos branch in an optimal way., Journal of Synchrotron Radiation, 26 (4), ISSN:0909-0495, ISSN:1600-5775

Osmium tetroxide bipyridine ([OsO4(bpy)]) is a versatile label for DNA electrochemistry. Here we report our efforts to create an osmium tetroxide-labeled immobilized DNA probe for use in biosensing experiments. Our label is applied in-house, as opposed to many other covalent redox labels used with DNA. We developed an on-electrode labeling method that was able to avoid attack of our disulfide-based linker by the [OsO4(bpy)]. Our results include two different hairpin-based signal-off hybridization detection assays, each with robust, reproducible signal decrease on binding to complementary target. We also found that 6-mercapto-1-hexanol was able to interact with [OsO4(bpy)] in a stable manner when assembled at the surface, but was able to remove excess [OsO4(bpy)], which was found to adsorb strongly to the gold surface, and avoid MCH transformation, when applied after the labeling process. Furthermore, we found an increased adsorption affinity of [OsO4(bpy)]-labeled DNA onto gold, characterized the redox behavior of adsorbed [OsO4(bpy)], and determined voltammetric signals on the HMDE of our intact disulfide linker while verifying that this linker is attacked by [OsO4(bpy)] when in solution.

We report about two new types of nanostructured gold electrodes that can be heated electrically. At the directly heated gold micro-wire electrode, the microelectrode behavior is diminished upon galvanic deposition of gold nanostructures. The voltammetric waves observed with ferrocyanide turned into peaks. This suggests that it is the active electrode area rather than the mere geometric dimensions, what determines microelectrode behavior. Direct heating of this nanostructured gold wire electrode brought back the wave-like voltammogramms typical for microelectrodes. We also demonstrate with a second type of heated gold electrode, an indirectly heated sensor based on low temperature co-fired ceramics (LTCC), that DNA hybridization response of covalently attached enzyme labels is greatly improved by nanostructures. The voltammetric signal increase for the nanostructured electrode was 22-fold at 5 °C and 6-fold at 70 °C electrode temperature. We think that a trapping effect in the gold pores greatly increases sensitivity, in particular at lower electrode temperature.

An electrochemical quartz crystal microbalance (EQCM) was employed to study the interactions of hexammine ruthenium(III) (RuHex) and hexammine cobalt(III) (CoHex) with a mixed self-assembled monolayer of single-stranded DNA and 6-mercapto-1-hexanol (ssDNA/MCH SAM) immobilized on gold electrodes. When the buffer medium was switched to deuterium oxide (D2O) from normal water (H2O), we observed a pronounced H/D kinetic isotope effect where a consistent shift of up to 400 mV was seen for the reduction peak potential of CoHex but not with RuHex. This was attributed to a 2400-fold change of the apparent reaction rate constant. Though there was a dramatic increase in the EQCM frequency response at a millisecond time scale in the presence of both redox indicators, compared to the signal observed in a low ionic strength buffer (10 mM tris(hydroxymethyl)aminomethane (Tris)/H2SO4 at pH 7.5), a 10 Hz decrease in the frequency shift was observed upon switching from H2O to D2O-based buffer medium. The hydrogen bond network within the ssDNA layer seems to amplify the H/D isotope effect with CoHex. Amplified isotope effects may play a role in living systems. The mechanisms of recently reported H/D isotope effects in medicinal and biochemistry are still widely unclear. Voltammetric and EQCM studies of H/D isotope effects can provide a platform to investigate amplified isotope effects not only with DNA layers, but probably also with proteins and small organic molecules and may be useful for studies of cell proliferation, as well as drug testing.

The development of visible-light-mediated allylation of unactivated sp

Preserving the coherence and wavefront of a diffraction limited x-ray beam from the source to the experiment poses stringent quality requirements on the production processes for X-ray optics. In the near future this will require on-line and in-situ at-wavelength metrology for both, free electron lasers and diffraction limited storage rings. A compact and easy to move X-ray grating interferometry (XGI) setup has been implemented by the Beamline Optics Group at PSI in order to characterize x-ray optical components by determining the aberrations from reconstructing the x-ray wavefront. The XGI setup was configured for measurements in the moire mode and tested with focusing optic at Swiss Light Source, Diamond Light Source and LCLS. In this paper measurements on a bendable toroidal mirror, a zone plate, a single and a stack of beryllium compound refractive lenses (CRL) are presented. From these measurements the focal position and quality of the beam spot in terms of wavefront distortions are determined by analysing the phase-signal obtained from the XGI measurement. In addition, using a bendable toroidal mirror, we directly compare radius of curvature measurements obtained from XGI data with data from a long-trace profilometer, and compare the CRL wavefront distortions with data obtained by ptychography.

The pollution of surface, ground and drinking water by pharmaceuticals in low concentration is a new emerging problem. Zinc oxide nanoparticles of different sizes have been characterized by XRD, TEM, UV–Vis/DRS and N2 adsorption–desorption measurements. The photocatalytic degradation of low concentrated pharmaceuticals tetracycline and ibuprofen at low photocatalyst amount and at low photocatalyst to substrate mass ratio (cat-to-sub ratio) have been investigated in details. The influence of pH value, ZnO and drug concentrations as well as the contribution of adsorption has been deeply studied. The formation of intermediates has been investigated by electrospray ionization-time of flight-mass spectroscopy. Zinc oxide is known to promote the formation of reactive OH radicals and therefore is of special interest for the photocatalytic remediation of water from pharmaceuticals. Smaller particles are more active than larger ones due to increased specific surface area and adsorption. Interestingly, adsorption of the drug on ZnO is markedly improved at low concentration (

5,7-Dihydropyrido[3,2-b:5,6-b′]diindoles were prepared by a highly efficient two-step synthesis that involved a site-selective Suzuki coupling reaction of 2,3,5,6-tetrabromopyridine and a subsequent Pd-catalyzed cyclization that proceeded through a twofold C–N coupling reaction with aromatic and aliphatic amines. With the exception of the parent molecule, which was described in a patent without any characterization data, the 5,7-dihydropyrido[3,2-b:5,6-b′]diindoles are a new chemical entity. Their electrochemical and photochemical properties were investigated. These pyridodiindoles show promising fluorescence properties with good quantum yields and interesting electrochemical behavior. The optical and electronical properties were analyzed and explained by using DFT calculations.

The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize the various aspects of the project, including the design of the soft and hard X-ray branches of the accelerator, the results of SwissFEL performance simulations, details of the photon beamlines and experimental stations, and our first commissioning results.

X-ray techniques have long been applied to chemical research, ranging from powder diffraction tools to analyse material structure to X-ray fluorescence measurements for sample composition. The development of high-brightness, accelerator-based X-ray sources has allowed chemists to use similar techniques but on more demanding samples and using more photon-hungry methods. X-ray Free Electron Lasers (XFELs) are the latest in the development of these large-scale user facilities, opening up new avenues of research and the possibility of more advanced applications for a range of research. The SwissFEL XFEL project at the Paul Scherrer Institute will begin user operation in the hard X-ray (2.1–12.4 keV) photon energy range in 2018 with soft X-ray (240–1930 eV) user operation to follow and here we will present the details of this project, it's operating capabilities, and some aspects of the experimental stations that will be particularly attractive for chemistry research. SwissFEL is a revolutionary new machine that will complement and extend the time-resolved chemistry efforts in the Swiss research community.

The Photo-Emission and Atomic Resolution Laboratory is a new soft X-ray beamline at the Swiss Light Source for the study of surface structure using photoelectron diffraction and scanning tunneling microscopy., The Photo-Emission and Atomic Resolution Laboratory (PEARL) is a new soft X-ray beamline and surface science laboratory at the Swiss Light Source. PEARL is dedicated to the structural characterization of local bonding geometry at surfaces and interfaces of novel materials, in particular of molecular adsorbates, nanostructured surfaces, and surfaces of complex materials. The main experimental techniques are soft X-ray photoelectron spectroscopy, photoelectron diffraction, and scanning tunneling microscopy (STM). Photoelectron diffraction in angle-scanned mode measures bonding angles of atoms near the emitter atom, and thus allows the orientation of small molecules on a substrate to be determined. In energy scanned mode it measures the distance between the emitter and neighboring atoms; for example, between adsorbate and substrate. STM provides complementary, real-space information, and is particularly useful for comparing the sample quality with reference measurements. In this article, the key features and measured performance data of the beamline and the experimental station are presented. As scientific examples, the adsorbate–substrate distance in hexagonal boron nitride on Ni(111), surface quantum well states in a metal-organic network of dicyano-anthracene on Cu(111), and circular dichroism in the photoelectron diffraction of Cu(111) are discussed.

Zr-doped titania of anatase structure type has been prepared by a combined sol–gel and chemical vapour deposition (CVD) process. The material has been characterized by XRD, TEM and chemical analysis. The photocatalytic performance has been investigated in the oxidative decomposition of the pharmaceutical ibuprofen (IBP) down to low ppm concentrations. The change of the composition of the reaction solution after photocatalytic treatment was followed by UV–Vis spectroscopy and GC/MS. Formation of reaction intermediates was studied by HPLC coupled electrospray ionization time-of-flight mass spectrometry ESI-TOF-MS. The catalytic performance has been studied by varying the catalyst and substrate concentration as well as changing the catalyst-to-substrate ratio. The influence of pH, adsorption and re-use of the catalyst has been tested. The results confirm the high catalytic activity of Zr-doped titania compared to pure titania at low catalyst loading. The material shows the improved textural mesoporosity. However, more reaction intermediates were formed, leading to faster deactivation of the photocatalyst. ESI-TOF-MS measurements point to the formation of a couple of reaction intermediates, which poison the catalyst.

The wiggler X-ray source of the Materials Science beamline at the Swiss Light Source has been replaced with a 14 mm-period cryogenically cooled in-vacuum undulator. In order to best exploit the increased brilliance of this new source, the entire front-end and optics have been redesigned., The Materials Science beamline at the Swiss Light Source has been operational since 2001. In late 2010, the original wiggler source was replaced with a novel insertion device, which allows unprecedented access to high photon energies from an undulator installed in a medium-energy storage ring. In order to best exploit the increased brilliance of this new source, the entire front-end and optics had to be redesigned. In this work, the upgrade of the beamline is described in detail. The tone is didactic, from which it is hoped the reader can adapt the concepts and ideas to his or her needs.

Since 2005 the Swiss Light Source (SLS) has been operating a Long Trace Profiler (LTP)-V from Ocean Optics in its metrology laboratory to measure the synchrotron optics for SLS. In 2012 we finished a significant upgrade to improve the accuracy, reliability and measurement efficiency in particular for the calibration of adaptive optics. Folding mirrors with figure errors λ / 100 and an additional linear encoder have been installed, the 1d CCD detector with 2048 pixels has been replaced by a 16 mega-pixel CCD camera with gigabit ethernet interface GigE, the monolithic software has been replaced by a modular, full- EPICS compatible system based on a new LTP plugin for the areaDetector software for image processing. The plugin allows slope determination in real time i.e. per frame.

We report about a new kind of directly heated gold electrode. All electrodes including a directly heated gold loop electrode, a Ag pseudo reference, and a carbon counter electrode have been screen-printed on a ceramic alumina substrate. Thermal behaviour was studied by potentiometry using either an external or the integrated reference electrode. Stripping voltammetric copper signals were greatly improved at elevated deposition temperature. Secondary ion mass spectrometric studies (ToF-SIMS) revealed that different negative ionic species of copper complexes can be found on the gold electrode surface as a result of ion bombardment during SIMS analysis like Cu−, CuCl− and CuCl2 −. SIMS surface imaging using a fine focussed ion beam over the surface allowed us to obtain ion images (chemical maps) of the analyzed sample. SIMS depth profile analysis of the gold loop electrode was performed after copper deposition at room temperature (23 °C) and at 60 °C. CuCl2 − ion was used for the depth profile studies as it has shown the highest intensity among other observed species. Surface spectroscopic analysis, surface imaging and depth profile analysis have shown that the amount of deposited copper species on the gold loop electrode was increased upon increasing electrode temperature during the deposition step. Therefore, the presence of chloride in the solution will hinder underpotential deposition of Cu(0) and lead to badly defined and resolved stripping peaks.

Due to the growing importance of low concentrated pollution of surface, ground and drinking, the photocatalytic decomposition of ibuprofen down to low ppm concentrations over titania catalyst has been investigated in detail. The catalyst was characterized by XRD, TEM, diffuse reflection UV–Vis and nitrogen adsorption measurement. The photocatalytic abatement of ibuprofen was monitored by UV–Vis spectrometry, chromatographic by GC/MS, and HPLC coupled electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). Catalytic performance has been studied by varying the catalyst and substrate concentration as well as decreasing the catalyst-to-substrate mass ratio over a wide range. The photocatalytic treatment with titania catalyst leads to rapid mineralization of ibuprofen. Formation of intermediate reaction products has been investigated. It is proposed that intermediates in part form oligomeric species, which are responsible for catalyst poisoning. Additional, the influence of the pH value, oxygen supply and catalyst re-use have been checked.

We report about hybridization detection of different nucleic acids on capture probe-modified heated gold wire electrodes. We have compared three kinds of nucleic acid targets: DNA, uracil-conjugated DNA, and RNA. All three sorts of nucleic acids targets could be labeled with osmium tetroxide bipyridine, hybridized with immobilized DNA capture probes and then detected by square-wave voltammetry. Heating the gold electrode instead of the entire bulk hybridization solution leads to improved hybridization efficiency in most cases. The reason could be found in a thermal micro-stirring effect around the heated wire electrode. Also selectivity was improved. Mismatches could be discriminated for DNA and uracil-conjugated DNA targets. Mismatches in RNA strands, however, are more difficult to detect due to relatively stable secondary structures.

The direct electrochemistry of a HRP–chi–[C 4 mim][BF 4 ] film (where HRP = horseradish peroxidase, chi = chitosan, and [C 4 mim][BF 4 ] = the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluoroborate) has been studied by cyclic voltammetry on a glassy carbon electrode. The mechanism for the electrochemical reaction of HRP is suggested to be EC for the reduction, and CE for the following re-oxidation, as the oxidative peak potential remained approximately unchanged across the scan rate range. The half wave potential of HRP reduction was found to be pH dependent, suggesting that a concomitant proton and electron transfer is occurring. Using theoretical simulations of the experimentally obtained peak positions, the standard electron transfer rate constant, k 0 , was found to be 98 (± 16) s − 1 at 295 K in pH 7 phosphate buffer solution, which is very close to the value reported in the absence of ionic liquid. This suggests that the ionic liquid used here in the HRP–chi–[C 4 mim][BF 4 ]/GC electrode does not enhance the rate of electron transfer. k 0 was found to increase systematically with increasing temperature and followed a linear Arrhenius relation, giving an activation energy of 14.20 kJ mol − 1 . The electrode kinetics and activation energies obtained are identical to those reported for HRP films in aqueous media. This leads us to question if the use of RTIL films provide any unique benefits for enzyme/protein voltammetry. Rather the films may likely contain aqueous zones in which the enzymes are located and undergo electron transfer.

A wavefront metrology setup based on the X-ray grating interferometry technique for spatially resolved, quantitative, in situ and at-wavelength measurements of the wavefront at synchrotron radiation and hard X-ray free-electron laser beamlines is reported. Indeed, the ever-increasing demands on the optical components to preserve the wavefront shape and the coherence of the delivered X-ray beam call for more and more sensitive diagnostic instruments. Thanks to its angular sensitivity, X-ray grating interferometry has been established in recent years as an adequate wavefront-sensing technique for quantitatively assessing the quality of the X-ray wavefront under working conditions and hence for the in situ investigation of X-ray optical elements. In order to characterize the optical elements at any given beamline by measuring the aberrations introduced in the wavefront, a transportable X-ray grating interferometry setup was realised at the Swiss Light Source (SLS). The instrument, which is expected to be a valuable tool for investigating the quality of the X-ray beam delivered at an endstation, will be described hereafter in terms of the hardware setup and the related data analysis procedure. Several exemplary experiments performed at the X05DA Optics beamline of the SLS will be presented.

We report about testing a new mobile and sustainable water sample digestion method in a preliminary field trial in Ethiopia. In order to determine heavy metals at the ultra-trace level by stripping voltammetric techniques in water samples from Awash River, we applied our new method of solar UV-assisted sample pretreatment to destroy the relevant interfering dissolved organic matter. The field tests revealed that 24 h of solar UV irradiation were sufficient to achieve the same sample pretreatment results as with classic digestion method based on intense and hard UV. Analytical results of this study suggest that both a hydroelectric power station and agrichemical applications at Koka Lake have increased the levels of the investigated metals zinc, cadmium, lead, copper, cobalt, nickel, and uranium.

SwissFEL is a free electron laser facility for hard and soft X-rays at the Paul Scherrer Institut in Switzerland. The first hard X-ray FEL named ARAMIS will deliver photons in the wavelength range from 1 A to 7 A in up to three beamlines alternatively. The beamlines are equipped with crystal monochromators, cover the full wavelength range and offer a variety of operational modes.

The article describes how solar ultraviolet-A radiation can be used to digest samples as needed for voltammetric ultratrace determination of uranium(VI) in river water. We applied adsorptive stripping voltammetry (AdSV) using chloranilic acid as the complexing agent. Samples from the river Warnow in Rostock (Germany) were pretreated with either soft solar UV or wit artificial hard UV from a 30-W source emitting 254-nm light. Samples were irradiated for 12 h, and both methods yielded the same results. We were able to detect around 1 μg·L−1 of uranium(VI) in a sample of river water that also contained dissolved organic carbon at a higher mg·L−1 levels. No AdSV signal was obtained for U(VI) without any UV pre-treatment. Pseudo-polarographic experiments confirmed the dramatic effect of both digestion techniques the the AdSV response. The new method is recommended for use in mobile ultratrace voltammetry of heavy metals for most kinds of natural water samples including tap, spring, ground, sea, and river waters. The direct use of solar radiation for sample pre-treatment represents a sustainable technique for sample preparation that does not consume large quantities of chemicals or energy.

We demonstrate an approach for the electrochemical detection of genetically modified maize in real maize flour samples by means of square-wave voltammetry (SWV). After labeling the asymmetric PCR-amplified targets with osmium tetroxide bipyridine [OsO4(bipy)], they were hybridized with immobilized oligonucleotide probes on gold electrodes. We could detect the maize genes ivrp and SSIIb in near isogenic maize. The transgene cryIa/b and the MON810 specific fragment were detected in all transgenic maize samples, down to a content of 0.6% of MON810 in mixed samples. While it was possible to detect all sequences in the samples containing 100% near isogenic or respectively transgenic maize after a hybridization time of less than 10 min, a hybridization time of 30 min was necessary for the detection of the genetic modifications in samples containing only 0.9 to 0.6% of transgenic maize. No significant detection of the transgene cryIa/b or MON810 was possible when only 0.5% of transgenic maize was present in the sample, most likely due to insufficient amplification of the template DNA. Keywords: Electrochemical DNA sensor, Hybridization, Gold electrode, Osmium tetroxide bipyridine, Real sample, Maize MON810

This article comprehensively reviews a selected subfield of thermoelectrochemistry, which bases upon joule-heated working electrodes. Both directly and indirectly heated electrodes are considered. In all cases, an electric current (AC or DC) is used to elevate the electrode temperature during the electrochemical processes. The development of joule-heated electrodes started as early as 1966 and was greatly accelerated by Grundler et al. since 1993. However, during the last 5 years the development became even faster, when other groups started to contribute novel approaches and designs on how to implement electrically heated electrodes in capillary electrophoreses and spectroelectrochemistry. To date there are more than 90 publications on heated electrodes.

The transport properties of single-strand DNA probe-modified self-propelling micromachines are exploited for "on-the-fly" hybridization and selective single-step isolation of target nucleic acids from "raw" microliter biological samples (serum, urine, crude E. coli lysate, saliva). The rapid movement of the guided modified microrockets induces fluid convection, which enhances the hybridization efficiency, thus enabling the rapid and selective isolation of nucleic acid targets from untreated samples. The integration of these autonomous microrockets into a lab-on-chip device that provides both nucleic acid isolation and downstream analysis could thus be attractive for diverse applications.

We present a new approach for efficient bender calibration and quality assessment on the example of a KB-mirror system for the refocusing stage at the new Phoenix beamline of the Swiss Light Source. To reach the target focus of about 2 μ m FWHM with the strong astigmatic imaging ratio of 70:1 in the vertical- and 50:1 in the horizontal direction the bender system of the mirror has to be carefully calibrated to reach the desired elliptic shape. We use off-line slope measurements with the Long Trace Profiler LTP-V from Ocean Optics in our metrology laboratory. The proprietary controls system of the LTP has been replaced by EPICS to allow automatic synchronized measurements over the whole parameter space of the benders. The data acquisition is implemented as four-dimensional scan using the standard EPICS sscan record. The controls of the hardware has been realized with a genSub record for the CCD detector and a stream device for the motion of the LTP head.

An electrochemical genosensor in which signal amplification is achieved using p-aminophenol (p-AP) redox cycling by nicotinamide adenine dinucleotide (NADH) is presented. An immobilized thiolated capture probe is combined with a sandwich-type hybridization assay, using biotin as a tracer in the detection probe, and streptavidin-alkaline phosphatase as reporter enzyme. The phosphatase liberates the electrochemical mediator p-AP from its electrically inactive phosphate derivative. This generated p-AP is electrooxidized at an Au electrode modified self-assembled monolayer to p-quinone imine (p-QI). In the presence of NADH, p-QI is reduced back to p-AP, which can be re-oxidized on the electrode and produce amplified signal. A detection limit of 1 pM DNA target is offered by this simple one-electrode, one-enzyme format redox cycling strategy. The redox cycling design is applied successfully to the monitoring of the 16S rRNA of E. coli pathogenic bacteria, and provides a detection limit of 250 CFU μL(-1).

The photocatalytic abatement of hazardous pharmaceuticals has been investigated at very low concentration in the ppb range as found in wastewater and in environmental pollutants. Photocatalytic degradation of tetracycline as a model compound with titania catalysts has been studied using solarium UV-A and black light with differentially applied electric power, tetracycline and catalyst concentration. Abatement of up to 90% has been achieved after 1 hour. Adsorption of tetracycline and photochemical degradation contribute significantly to the abatement of tetracycline resulting in an immediate reduction during the initial period of treatment. Contribution of adsorption is high at very low concentration (500 ppb). Photocatalytic treatment with titania is even highly efficient in the abatement of very small concentrations of tetracycline in drinking water.

This paper reviews past and current developments in the field of electrochemical biosensors with a focus on the sequence-specific detection of nucleic acids in real samples. After electrochemical hybridization sensors had been first described in 1993, it took nearly a decade until some of the many proposed protocols were indeed applied to real samples like blood or tissue. Electrochemical transduction schemes used either rely on electroactive moieties such as intercalators, groove binders, covalently attached labels, and products of enzyme markers or they are completely indicator free like impedance-based detection principles. Most detection schemes require a polymerase chain reaction amplification step to allow for sufficient selectivity and sensitivity. Today, several companies develop electrochemical microarrays able to detect dozens to many thousands of sequences in a single experiment.

As a nontoxic substitute for mercury electrodes, bismuth electrodes attained a lot of attention during the last years. In this report we describe for the first time the preparation of two different directly heatable bismuth-modified microwire electrodes. We characterized the electrochemical behaviour using cyclic voltammetry in acetate buffer and alkaline tartrate solution. The bismuth electrodes show a significantly wider potential window compared with bare gold wires. In the presence of picric acid as one example for the detection of explosives, the bismuth electrodes deliver higher signals. By applying heat during the measurements, the signals can be enhanced further. We used the temperature pulse amperometry (TPA) technique to improve the electrochemical response at the different types of electrodes. In this preliminary study, we were able to detect 3 ppm traces of picric acid.