A split and delay unit for the European XFEL

For the European XFEL [1] an x ray split and delay unit SDU is built covering photon energies from 5 keV up to 20 keV [2]. This SDU will enable time resolved x ray pump x ray probe experiments as well as sequential diffractive imaging [3] on a femtosecond to picosecond time scale. Further, direct measurements of the temporal coherence properties will be possible by making use of a linear autocorrelation. The set up is based on geometric wavefront beam splitting, which has successfully been implemented at an autocorrelator at FLASH [4]. The x ray FEL pulses will be split by a sharp edge of a silicon mirror coated with Mo B4C multi layers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. For a photon energy of h 20 keV a grazing angle of 0.57 has to be set, which results in a footprint of the beam on the mirror of l 120 mm. At this photon energy the reflectance of a Mo B4 C multi layer coating with a multi layer period of d 3.2 nm and N 200 layers amounts to R 0.92. In order to enhance the maximum transmission for photon energies of h 8 keV and below, a Ni B4C multilayer coating can be applied beside the Mo B4C coating for this spectral region. Because of the different incidence angles, the path lengths of the beams will differ as a function of wavelength. Hence, maximum delays between 2.5 ps at h 20 keV and up to 23 ps at h 5 keV will be possibl

Studienprotokoll: Register zur Prognose akut-symptomatischer Anfälle (PROSA-Register) – eine prospektive multizentrische Beobachtungsstudie

Background: Acute symptomatic epileptic seizures occur in close temporal relation to an acute disturbance of brain function. They are associated with a low risk of subsequent unprovoked seizures; thus, current guidelines recommend not to administer a long-term antiseizure medication; however, in clinical practice long-term secondary seizure prophylaxis is frequently initiated. The seizure prognosis after guideline-conform untreated or only briefly treated acute symptomatic seizures, is so far unknown. Hypothesis: Following an acute symptomatic first epileptic seizure of structural etiology, the 1-year risk of subsequent unprovoked seizures is not higher than 25%, even if antiseizure medication was not applied or for a short period only. Methods: The PROSE register is a single-arm, open, prospective, multicenter observational study. A total of 115 subjects aged 18 years or older with an acute symptomatic first epileptic seizure of structural etiology will be included if the seizure was not a status epilepticus. Intrahospital follow-up will be based on the hospital records. Telephone follow-up interviews will be conducted 3, 6, and 12 months after the acute symptomatic seizure. Discussion: The PROSE register will shed light on current treatment practice of acute symptomatic seizures and the actual seizure outcome within 1 year. The results are assumed to support the current evidence that giving antiseizure medication for a longer period of time exceeding the acute phase of the underlying condition is unnecessary

Effects of state-wide implementation of the Los Angeles Motor Scale for triage of stroke patients in clinical practice

Background: The prehospital identification of stroke patients with large-vessel occlusion (LVO), that should be immediately transported to a thrombectomy capable centre is an unsolved problem. Our aim was to determine whether implementation of a state-wide standard operating procedure (SOP) using the Los Angeles Motor Scale (LAMS) is feasible and enables correct triage of stroke patients to hospitals offering (comprehensive stroke centres, CSCs) or not offering (primary stroke centres, PSCs) thrombectomy.Methods: Prospective study involving all patients with suspected acute stroke treated in a 4-month period in a state-wide network of all stroke-treating hospitals (eight PSCs and two CSCs). Primary endpoint was accuracy of the triage SOP in correctly transferring patients to CSCs or PSCs. Additional endpoints included the number of secondary transfers, the accuracy of the LAMS for detection of LVO, apart from stroke management metrics.Results: In 1123 patients, use of a triage SOP based on the LAMS allowed triage decisions according to LVO status with a sensitivity of 69.2% (95% confidence interval (95%-CI): 59.0-79.5%) and a specificity of 84.9% (95%-CI: 82.6-87.3%). This was more favourable than the conventional approach of transferring every patient to the nearest stroke-treating hospital, as determined by geocoding for each patient (sensitivity, 17.9% (95%-CI: 9.4-26.5%); specificity, 100% (95%-CI: 100-100%)). Secondary transfers were required for 14 of the 78 (17.9%) LVO patients. Regarding the score itself, LAMS detected LVO with a sensitivity of 67.5% (95%-CI: 57.1-78.0%) and a specificity of 83.5% (95%-CI: 81.0-86.0%).Conclusions: State-wide implementation of a triage SOP requesting use of the LAMS tool is feasible and improves triage decision-making in acute stroke regarding the most appropriate target hospital.</p

Tunable two-color hard x-ray multilayer Bragg mirrors

A tunable two-color multilayer Bragg coating capable of simultaneously reflecting the fundamental and the third harmonic of an x-ray free-electron laser at the same angle and with high reflectance R > 0.70 is presented. The novel coating will enable two-color x-ray pump/x-ray probe experiments. This mirror consists of a Si substrate that is coated with two different types of multilayer systems, Mo/B4C layers with a periodicity of d = 3.2 nm directly on the substrate and Ni/B4C layers with a periodicity of d = 11.85 nm on top. Fundamental radiation with photon energies between 3 and 9 keV is reflected by a Ni/B4C multilayer system while the third harmonic (9 keV < h nu < 27 keV) passes this system and is reflected by the Mo/B4C multilayers. The principle has successfully been proven at the beamline BM05 at ESRF

High-Purity Corundum as Support for Affinity Extractions from Complex Samples

Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, EDS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids were used to introduce functional groups for further conjugations. The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower non-specific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A binding capacity of 1.8 mg IgG per gram of corundum powder was achieved. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application

High-Purity Corundum as Support for Affinity Extractions from Complex Samples

Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, EDS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids were used to introduce functional groups for further conjugations. The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower non-specific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A binding capacity of 1.8 mg IgG per gram of corundum powder was achieved. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application

Rapid aberration correction for diffractive X-ray optics by additive manufacturing

Diffraction-limited hard X-ray optics are key components for high-resolution microscopy, in particular for upcoming synchrotron radiation sources with ultra-low emittance. Diffractive optics like multilayer Laue lenses (MLL) have the potential to reach unprecedented numerical apertures (NA) when used in a crossed geometry of two one-dimensionally focusing lenses. However, minuscule fluctuations in the manufacturing process and technical limitations for high NA X-ray lenses can prevent a diffraction-limited performance. We present a method to overcome these challenges with a tailor-made refractive phase plate. With at-wavelength metrology and a rapid prototyping approach we demonstrate aberration correction for a crossed pair of MLL, improving the Strehl ratio from 0.41(2) to 0.81(4) at a numerical aperture of 3.3 × 10$^{−3}$. This highly adaptable aberration-correction scheme provides an important tool for diffraction-limited hard X-ray focusing

Interactive Volumetry Of Liver Ablation Zones

Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm’s results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.Peer reviewe

Mechanical thrombectomy in acute ischaemic stroke patients with pre-interventional intracranial haemorrhage following intravenous thrombolysis

Background: Data on outcome of endovascular treatment in patients with acute ischaemic stroke due to large vessel occlusion suffering from intravenous thrombolysis-associated intracranial haemorrhage prior to mechanical thrombectomy remain scarce. Addressing this subject, we report our multicentre experience. Methods: A retrospective analysis of consecutive acute ischaemic stroke patients treated with mechanical thrombectomy due to large vessel occlusion despite the pre-interventional occurrence of intravenous thrombolysis-associated intracranial haemorrhage was performed at five tertiary care centres between January 2010-September 2020. Baseline demographics, aetiology of stroke and intracranial haemorrhage, angiographic outcome assessed by the Thrombolysis in Cerebral Infarction score and clinical outcome evaluated by the modified Rankin Scale at 90 days were recorded. Results: In total, six patients were included in the study. Five individuals demonstrated cerebral intraparenchymal haemorrhage on pre-interventional imaging; in one patient additional subdural haematoma was observed and one patient suffered from isolated subarachnoid haemorrhage. All patients except one were treated by the 'drip-and-ship' paradigm. Successful reperfusion was achieved in 4/6 (67%) individuals. In 5/6 (83%) patients, the pre-interventional intracranial haemorrhage had aggravated in post-interventional computed tomography with space-occupying effect. Overall, five patients had died during the hospital stay. The clinical outcome of the survivor was modified Rankin Scale=4 at 90 days follow-up. Conclusion: Mechanical thrombectomy in patients with intravenous thrombolysis-associated intracranial haemorrhage is technically feasible. The clinical outcome of this subgroup of stroke patients, however, appears to be devastating with high mortality and only carefully selected patients might benefit from endovascular treatment