Evaluating the impact of a rigid and a deformable registration method of pre-treatment images for hypoxia-based dose painting

PURPOSE

To assess the impact of rigid and deformable image registration methods (RIR, DIR) on the outcome of a hypoxia-based dose painting strategy.

MATERIALS AND METHODS

Thirty head and neck cancer patients were imaged with [18F]FMISO-PET/CT before radiotherapy. [18F]FMISO-PET/CT images were registered to the planning-CT by RIR or DIR. The [18F]FMISO uptake was converted into oxygen partial pressure (pO2) maps. Hypoxic Target Volumes were contoured on pO2 maps for the deformed (HTVdef) and non-deformed (HTV) cases. A dose escalation strategy by contours, aiming at 95 % tumour control probability (TCP), was applied. HTVs were characterised based on geometry-related metrics, the underlying pO2 distribution, and the dose boost level. A dosimetric and radiobiological evaluation of selected treatment plans made considering RIR and DIR was performed. Moreover, the TCP of the RIR dose distribution was evaluated when considering the deformed [18F]FMISO-PET image as an indicator of the actual target radiosensitivity to determine the potential impact of an unalignment.

RESULTS

Statistically significant differences were found between HTV and HTVdef for volume-based metrics and underlying pO2 distribution. Eight out of nine treatment plans for HTV and HTVdef showed differences on the level 10 %/3 mm on a gamma analysis. The TCP difference, however, between RIR and the case when the RIR dose distribution was used with the deformed radiosensitivity map was below 2 pp.

CONCLUSIONS

Although the choice of the CTplan-to-PET registration method pre-treatment impacts the HTV localisation and morphology and the corresponding dose distribution, it negligibly affects the TCP in the proposed dose escalation strategy by contours.

Increased Readiness for Water Splitting: NiO-Induced Weakening of Bonds in Water Molecules as Possible Cause of Ultra-Low Oxygen Evolution Potential

The development of non-precious metal-based electrodes that actively and stably support the oxygen evolution reaction (OER) in water electrolysis systems remains a challenge, especially at low pH levels. The recently published study has conclusively shown that the addition of haematite to H2 SO4 is a highly effective method of significantly reducing oxygen evolution overpotential and extending anode life. The far superior result is achieved by concentrating oxygen evolution centres on the oxide particles rather than on the electrode. However, unsatisfactory Faradaic efficiencies of the OER and hydrogen evolution reaction (HER) parts as well as the required high haematite load impede applicability and upscaling of this process. Here it is shown that the same performance is achieved with three times less metal oxide powder if NiO/H2 SO4 suspensions are used along with stainless steel anodes. The reason for the enormous improvement in OER performance by adding NiO to the electrolyte is the weakening of the intramolecular O─H bond in the water molecules, which is under the direct influence of the nickel oxide suspended in the electrolyte. The manipulation of bonds in water molecules to increase the tendency of the water to split is a ground-breaking development, as shown in this first example.

The readiness of water molecules to split into hydrogen + oxygen: a proposed new aspect of water splitting

The potential of the anode, at which the evolution of oxygen begins, is a key parameter that describes how well water is split in water electrolyzers. Research efforts related to electrocatalytically initiated water splitting that aimed at reducing the oxygen evolution reaction (OER) overpotential to date focused on the optimization of materials used to produce the electrodes. Descriptors for the readiness of the H₂ O molecule itself to break down into its components have not been considered in water electrolysis experiments so far. In a simple set of experiments, we found that adding dioxane to aqueous solutions leads to a substantial blue shift of the frequency of the O-H stretch vibration which is a sign for an increased strength of the O-H bond (intramolecular bonding). This phenomenon coincides with a significant increase of the OER onset potential as derived from cyclic voltammetry experiments. Thus, the O-H stretch frequency can be an ideal indicator for the readiness of water molecules to be split in its cleavage products. To our knowledge this is the first example of a study into the relationship between structural features of water as derived from FTIR spectroscopic studies, and key results derived from water electrolysis experiments. This article is protected by copyright. All rights reserved.

Water electrolysis: from textbook knowledge to the latest scientific strategies and industrial developments

Replacing fossil fuels with energy sources and carriers that are sustainable, environmentally benign, and affordable is amongst the most pressing challenges for future socio-economic development. To that goal, hydrogen is presumed to be the most promising energy carrier. Electrocatalytic water splitting, if driven by green electricity, would provide hydrogen with minimal CO2 footprint. The viability of water electrolysis still hinges on the availability of durable earth-abundant electrocatalyst materials and the overall process efficiency. This review spans from the fundamentals of electrocatalytically initiated water splitting to the very latest scientific findings from university and institutional research, also covering specifications and special features of the current industrial processes and those processes currently being tested in large-scale applications. Recently developed strategies are described for the optimisation and discovery of active and durable materials for electrodes that ever-increasingly harness first-principles calculations and machine learning. In addition, a technoeconomic analysis of water electrolysis is included that allows an assessment of the extent to which a large-scale implementation of water splitting can help to combat climate change. This review article is intended to cross-pollinate and strengthen efforts from fundamental understanding to technical implementation and to improve the 'junctions' between the field's physical chemists, materials scientists and engineers, as well as stimulate much-needed exchange among these groups on challenges encountered in the different domains.

Biopsy-Derived Oral Keratinocytes – a Model to Potentially Test for Oral Mucosa Radiation Sensitivity

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Human oral keratinocytes – the key players in radiation mucositis in head and neck cancer treatment – are established ex vivo from patient-derived micro-biopsies.

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Individual radiosensitivity of primary oral keratinocytes is measured by a novel assay for cellular proliferation and spreading.

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The keratinocyte model also supports classical functional assays such as clonogenic survival and DNA double strand repair.

Purpose

To establish stable in vitro growth of keratinocytes from very small biopsy specimens and successfully apply new test systems to determine their radiosensitivity.

Materials and Methods

Oral mucosa biopsies (diameter: 1.7 mm) from 15 subjects were immobilized with custom-made cups onto culture plates. Outgrowing cells were tested for cytokeratin 5/14 and Ki67, expanded, radiated at different doses, and seeded onto circumscribed areas before being allowed to spread centrifugally. In this newly developed spreading assay, cell-covered areas were measured by image analysis. For statistical analysis, a linear mixed regression model was used; additionally, results were correlated to the radiation dose applied. Colony forming efficiency (CFE) was used to validate the results. DNA damage repair was analysed by gammaH2AX and 53BP1 foci quantification using immunofluorescence microscopy 24 h and 96 h after irradiation.

Results

Stable keratinocyte growth continued for up to 7 weeks in 14 biopsies. Cells spread reliably from an initial 16.6 mm² up to a median of 119.2 mm² (range: 54.4–290). Radiated cells spread to only 100.7 mm² (2 Gy; range: 55.3–266.7); 73.2 mm² (4 Gy; 15–240.4); 47 mm² (6 Gy; 2–111.9), and 22.7 mm² (8 Gy; 0–80). Similarly, CFE decreased from 0.223 (0 Gy) to 0.0028 (8 Gy). Using an individual donor as a random factor, cell spread correlated with CFE, where radiation dose was the main driver (decrease by 0.50, adjusted for area). Upon irradiation with 6 Gy, radiation-induced DNA damage was increased after 24 h in all samples, and even after 96 h in 5 out of 7 samples, as detected by a higher number of gammaH2AX/53BP1 foci in irradiated cells (mean 3.7 for 24 h; mean 0.6 for 96 h).

Conclusion

In vitro propagation of keratinocytes derived from a small biopsy is feasible. Radiation impairs cellular migration and proliferation, and the newly described spreading assay allows ranking for cellular radioresistance. The keratinocyte model also supports classical functional assays such as clonogenic survival and DNA double strand repair. The clinical relevance awaits upcoming investigations.

[Weaning from Mechanical Ventilation in Patients with SARS-CoV-2 Infection after Prolonged Mechanical Ventilation - First Experience]

AIM

 With the emergence of a new virus and the associated pandemic, the ICU started to see a brand new kind of patient with severe ARD. As with any disease, sometimes the discontinuation of mechanical ventilation for any reason can be difficult. As a center specializing in weaning patients after prolonged mechanical ventilation, we wanted to compare our results with weaning patients who had prolonged mechanical ventilation for other reasons than those of patients who had prolonged mechanical ventilation due to SARS-CoV-2 infection.

METHODS

 We obtained our data from WeanNet register, the weaning register of the German Institute for Lung Research (ILF). In our analysis, we included only patient data from January until July 2020, which was recorded in our in-house study files.

RESULTS

 Our analysis included data on 28 patients; 11 were treated with prolonged mechanical ventilation due to SARS-CoV-2 pneumonia, 17 had no SARS-CoV-2 infection. 81.2 % of SARS-CoV-2 patients were successfully weaned from invasive ventilator therapy compared to 76.4 % of patients without SARS-CoV-2. Mortality in the SARS-CoV-2 group was 18.2 % compared to 11.8 % in the other group. Patients with SARS-CoV-2 infections were predominantly males with preexisting cardiovascular disease or a history of nicotine abuse. ARDS was the most common cause of respiratory failure which led to primary intubation.

CONCLUSION

 Even though we were only able to analyze a small number of patient histories due to the novelty of the disease, we were able to show that patients with prolonged mechanical ventilation after SARS-CoV-2 infection can be equally successfully weaned compared to patients with prolonged mechanical ventilation due to other diseases. Risk factors for prolonged mechanical ventilation after a severe case of SARS-CoV-2 infection seemed to be male gender, nicotine abuse and cardiovascular disease.

HIV DNA reservoir and elevated PD-1 expression of CD4 T-cell subsets particularly persist in the terminal ileum of HIV-positive patients despite cART

OBJECTIVES

Despite its importance as an HIV anatomic sanctuary, little is known about the characteristics of the HIV reservoir in the terminal ileum (TI). In blood, the immune checkpoint inhibitor programmed-death-1 (PD-1) has been linked to the HIV reservoir and T-cell immune dysfunction. We thus evaluated PD-1 expression and cell-associated HIV DNA in memory CD4 T-cell subsets from TI, peripheral blood (PB) and rectum (RE) of untreated and treated HIV-positive patients to identify associations between PD-1 and HIV reservoir in other sites.

METHODS

Using mononuclear cells from PB, TI and RE of untreated HIV-positive (N = 6), treated (n = 18) HIV-positive and uninfected individuals (n = 16), we identified and sorted distinct memory CD4 T-cell subsets by flow cytometry, quantified their cell-associated HIV DNA using quantitative PCR and assessed PD-1 expression levels using geometric mean fluorescence intensity. Combined HIV-1 RNA in situ hybridization and immunohistochemistry was performed on ileal biopsy sections.

RESULTS

Combined antiretroviral therapy (cART)-treated patients with undetectable HIV RNA and significantly lower levels of HIV DNA in PB showed particularly high PD-1 expression in PB and TI, and high HIV DNA levels in TI, irrespective of clinical characteristics. By contrast, in treatment-naïve patients HIV DNA levels in memory CD4 T-cell subsets were high in PB and TI.

CONCLUSION

Elevated PD-1 expression on memory CD4 T-cells in PB and TI despite treatment points to continuous immune dysfunction and underlines the importance of evaluating immunotherapy in reversing HIV latency and T-cell reconstitution. As HIV DNA particularly persists in TI despite cART, investigating samples from TI is crucial in understanding HIV immunopathogenesis.

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

The electrodeposition of noble metals using corresponding dissolved metal salts represents an interesting process for the improvement of the electrocatalytic hydrogen evolution reaction (HER) properties of less active substrate materials. The fact that only a small fraction of the dissolved noble metals reaches the substrate represents a serious obstacle to this common procedure. We therefore chose a different path. It was found that the HER activity of Ni42 alloy drastically increased (η=140 mV at j=10 mA cm⁻²; pH 1) when a platinum counter electrode was used during polarization experiments in acid. This improvement was caused by a platinum transfer from the platinum anode to the steel cathode, a process which occurred simultaneously to the hydrogen evolution. The negligible accumulation of Pt (26 μg) in the electrolyte turns this straight‐forward transfer procedure into a highly cost‐effective, environmentally friendly, and waste reducing approach for the generation of cheap, stable and effective HER electrodes.

Alveolar capillary dysplasia with left heart obstruction - rare but lethal

Alveolar capillary dysplasia (ACD) is a rare neonatal lung disease characterized anatomically by a defective and hypoplastic development of pulmonary alveoli leading to persistent pulmonary hypertension (PPHN) and finally lethal respiratory failure. It is often associated with congenital left heart obstruction. Given the fatal prognosis an early diagnosis is important. However, due to the fast onset of PPHN in neonates and lack of pathognomonic signs for its cause, safe and fast detection of ACD is challenging. Therefore, following the exclusion of cardiac and common pulmonary causes, lung biopsy becomes essential for diagnosis.We hereby report a case of ACD with atrial septal defect type one and hypoplastic aortic arch with an ante-mortem diagnosis and discuss the current state of medicine in relation to ACD.

Free-Sustaining Three-Dimensional S235 Steel-Based Porous Electrocatalyst for Highly Efficient and Durable Oxygen Evolution

A novel oxygen evolution reaction (OER) catalyst (3 D S235-P steel) based on a steel S235 substrate was successfully prepared by facile one-step surface modification. The standard carbon-manganese steel was phosphorized superficially, which led to the formation of a unique 3 D interconnected nanoporous surface with a high specific area that facilitated the electrocatalytically initiated oxygen evolution reaction. The prepared 3 D S235-P steel exhibited enhanced electrocatalytic OER activities in the alkaline regime, as confirmed by a low overpotential (326 mV at a 10 mA cm^-2 ) and a small Tafel slope of 68.7 mV dec^-1 . Moreover, the catalyst was found to be stable under long-term usage conditions, functioning as an oxygen-evolving electrode at pH 13, as evidenced by the sufficient charge-to-oxygen conversion rate (faradaic efficiency: 82.11 and 88.34 % at 10 and 5 mA cm^-2 , respectively). In addition, it turned out that the chosen surface modification delivered steel S235 as an OER electrocatalyst that was stable under neutral pH conditions. Our investigation revealed that the high catalytic activities likely stemmed from the generated Fe/(Mn) hydroxide/oxohydroxides generated during the OER process. Phosphorization treatment therefore not only is an efficient way to optimize the electrocatalytic performance of standard carbon-manganese steel but also enables for the development of low-costing and abundant steels in the field of energy conversion.

Ordered Topographically Patterned Silicon by Insect-Inspired Capillary Submicron Stamping

Insect-inspired capillary submicron stamping and subsequent surface-limited metal-assisted chemical etching (MACE) with ammonium bifluoride as a HF source are employed for the high-throughput production of ordered topographically patterned silicon (tpSi). Insect feet often possess hairy contact elements through which adhesive secretion is deployed. Thus, arrays of adhesive secretion drops remain as footprints on contact surfaces. Stamps for insect-inspired capillary submicron stamping having surfaces topographically patterned with contact elements mimic the functional principles of such insect feet. They contain spongy continuous nanopore networks penetrating the entire stamps. Any ink (organic or aqueous) may be supplied from the backside of the nanoporous stamps to the contact elements. We generated ordered arrays of submicron AgNO₃ dots extending square millimeters on Si by manual stamping with cycle times of a few seconds under ambient conditions; at higher load, ordered holey AgNO₃ films were obtained. Surface-limited MACE correspondingly yielded either macroporous tpSi or Si pillar arrays. Inkjet printing of polymer solutions onto the tpSi yielded patterns of polymer blots conformally covering the tpSi. Such blot patterns could potentially represent a starting point for the development of persistent and scratch-resistant identity labels or quick response codes on silicon surfaces.

Electrochemical initiation of electron-catalyzed phenanthridine synthesis by trifluoromethylation of isonitriles

Electrochemical initiation of the trifluoromethylation of biaryl isonitriles verifies the electron's catalytic character in the examined cascade reaction.

Steel-based electrocatalysts for efficient and durable oxygen evolution in acidic media

Upon electro-oxidation in LiOH, Ni42 alloy was rendered in an OER electrocatalyst that efficiently and durably works in the acidic regime.

Electro-oxidation of a cobalt based steel in LiOH: a non-noble metal based electro-catalyst suitable for durable water-splitting in an acidic milieu

The use of proton exchange membrane (PEM) electrolyzers is the method of choice for the conversion of solar energy when frequently occurring changes of the current load are an issue. However, this technique requires electrolytes with low pH. All oxygen evolving electrodes working durably and actively in acids contain IrO_x. Due to their scarcity and high acquisition costs, noble elements like Pt, Ru and Ir need to be replaced by earth abundant elements. We have evaluated a cobalt containing steel for use as an oxygen-forming electrode in H₂SO₄. We found that the dissolving of ingredients out of the steel electrode at oxidative potential in sulfuric acid, which is a well-known, serious issue, can be substantially reduced when the steel is electro-oxidized in LiOH prior to electrocatalysis. Under optimized synthesis conditions a cobalt-containing tool steel was rendered into a durable oxygen evolution reaction (OER) electrocatalyst (weight loss: 39 μg mm^-2 after 50 000 s of chronopotentiometry at pH 1) that exhibits overpotentials down to 574 mV at 10 mA cm^-2 current density at pH 1. Focused ion beam SEM (FIB-SEM) was successfully used to create a structure-stability relationship.

Oxidized Mild Steel S235: An Efficient Anode for Electrocatalytically Initiated Water Splitting

The surface of steel S235 was oxidized by Cl2 gas and checked for its electrocatalytic efficiency regarding oxygen formation in aqueous solution. If exposed to humid Cl2 gas for 110 min, steel S235 became an electrocatalyst that exhibits an overpotential for the oxygen evolution reaction (OER) of 462 mV at 1 mA cm(-2) at pH 7. The OER activity of the same sample at pH 13 was moderate (347 mV overpotential at 2.0 mA cm(-2) current density) in comparison with OER electrocatalysts developed recently. Potential versus time plots measured at a constant current demonstrate the sufficient stability of all samples under catalysis conditions at pH 7 and 13 for tens of hours. High-resolution X-ray photoelectron spectra could be reasonably resolved with the proviso that Fe2 O3 , FeO(OH), MnO(OH), and Mn2 O3 are the predominant Fe and Mn species on the surface of the oxidized steel S235.

Ultrafine sanding paper: a simple tool for creating small particles

A top-down approach, i.e., creating small particles by mechanical force starting from bulk materials, probably presents the most logical approach to particle size reduction and, therefore, top-down techniques are among the first to achieve small particles. A new solvent-free, amazingly simple approach is reported, suitable to achieve nanoparticles and sub-micro particles.

Organic melt, electride, and CVD induced in situ deposition of luminescent lanthanide imidazolate MOFs on nanostructured alumina

Highly luminescent MOF coatings were grown on nanostructured alumina membranes via melt, electride and CVD approaches.

Biomarker driven population enrichment for adaptive oncology trials with time to event endpoints

The development of molecularly targeted therapies for certain types of cancers has led to the consideration of population enrichment designs that explicitly factor in the possibility that the experimental compound might differentially benefit different biomarker subgroups. In such designs, enrollment would initially be open to a broad patient population with the option to restrict future enrollment, following an interim analysis, to only those biomarker subgroups that appeared to be benefiting from the experimental therapy. While this strategy could greatly improve the chances of success for the trial, it poses several statistical and logistical design challenges. Because late-stage oncology trials are typically event driven, one faces a complex trade-off between power, sample size, number of events, and study duration. This trade-off is further compounded by the importance of maintaining statistical independence of the data before and after the interim analysis and of optimizing the timing of the interim analysis. This paper presents statistical methodology that ensures strong control of type 1 error for such population enrichment designs, based on generalizations of the conditional error rate approach. The special difficulties encountered with time-to-event endpoints are addressed by our methods. The crucial role of simulation for guiding the choice of design parameters is emphasized. Although motivated by oncology, the methods are applicable as well to population enrichment designs in other therapeutic areas.

Coherent structural dynamics of a prototypical charge-density-wave-to-metal transition

Using femtosecond time-resolved x-ray diffraction, we directly monitor the coherent lattice dynamics through an ultrafast charge-density-wave-to-metal transition in the prototypical Peierls system K(0.3)MoO(3) over a wide range of relevant excitation fluences. While in the low fluence regime we directly follow the structural dynamics associated with the collective amplitude mode; for fluences above the melting threshold of the electronic density modulation we observe a transient recovery of the periodic lattice distortion. We can describe these structural dynamics as a motion along the coordinate of the Peierls distortion triggered by the prompt collapse of electronic order after photoexcitation. The results indicate that the dynamics of a structural symmetry-breaking transition are determined by a high-symmetry excited state potential energy surface distinct from that of the initial low-temperature state.

Die Struktur von SrCuSn2 und BaCuSn2 und ihre Verwandtschaft zum BiOCl-Gitter / The Structure of SrCuSn2 and BaCuSn2 and its Relationship to the BiOCl-Structure

The compounds SrCuSn2 and BaCuSn2 have been prepared and their crystal structures have been determined. They crystallize in a lattice (space-group Cmcm-D17 2h) related to that of the BiOCl-type.

Zur Struktur der Verbindung TlTe / On the Structure of TlTe

The crystal structure of TlTe was redetermined and by this way the Te-sublattice corrected. There are short Te-Te atomic distances which are comparable with covalent Te-Te bond distances.

Darstellung und Kristallstruktur des K2Sb4S7 / Preparation and Crystal Structure of K2Sb4S7

In the K2S/Sb2S3-System the compound K2Sb4S7 has been prepared and its structure determined. In this structure there are two differently coordinated Sb-atoms: the SbI-atoms in the vertices of flat SbS3-pyramides have the CN 3 to sulfur, the SbII-atoms are ψ-trigonal-bipyramidal coordinated with one free position in the equatorial plane. These polyhedra are connected to each other by common corners and edges to a three-dimensional net, which has channels parallel the b-axis, in which the K+-ions are located.

Die Kristallstrukturen der Verbindungen Ca5Si3 und Ca5Ge3 / The Crystal Structures of Ca5Si3 and Ca5Ge3

The new compounds Ca5Si3 and Ca5Ge3 were prepared and their structure determined.

They crystallize in the Cr5B3-structure type.

Zur Kenntnis einer neuen SrSi-Modifikation und der Phase SrGe0,76 / On a New SrSi-Modification and the New Compound SrGe0,76

A new SrSi-modification and the new phase SrGe0,76 were prepared and their structures determined. In these compounds the elementlVatoms form planar hexagons substituted in the 1, 2, 4, 5-positions by four additional Si(Ge)atoms. In the compound SrGe0,76 there are defects in this unit in the positions 1, 2, 4, 5, while in SrSi no indications of such defects could be found.