Melt-cast materials: combining the advantages of highly nitrated azoles and open-chain nitramines

Numerous efforts to substitute TNT as the melt-cast matrix in explosive charges are ongoing due to its low performance and security issues. In this study the syntheses and full structural as well as spectroscopic characterizations of 2-nitrazapropyl substituted polynitroazoles, as potential melt-cast explosives, are presented. This straightforward method of derivatizing the heterocyclic N–H function by introducing a further energetic group improved the stability and energetic properties of the products. X-ray crystallographic measurements were performed for all compounds and afforded insights into structural characteristics such as strong intermolecular interactions. All compounds were characterized in terms of their sensitivities towards impact, friction and electrostatic discharge, and their thermal stabilities. The energetic properties were calculated with the EXPLO5 6.02 program

Metabolic engineering of Halomonas elongata: Ectoine secretion is increased by demand and supply driven approaches

The application of naturally-derived biomolecules in everyday products, replacing conventional synthetic manufacturing, is an ever-increasing market. An example of this is the compatible solute ectoine, which is contained in a plethora of treatment formulations for medicinal products and cosmetics. As of today, ectoine is produced in a scale of tons each year by the natural producer Halomonas elongata. In this work, we explore two complementary approaches to obtain genetically improved producer strains for ectoine production. We explore the effect of increased precursor supply (oxaloacetate) on ectoine production, as well as an implementation of increased ectoine demand through the overexpression of a transporter. Both approaches were implemented on an already genetically modified ectoine-excreting strain H. elongata KB2.13 (ΔteaABC ΔdoeA) and both led to new strains with higher ectoine excretion. The supply driven approach led to a 45% increase in ectoine titers in two different strains. This increase was attributed to the removal of phosphoenolpyruvate carboxykinase (PEPCK), which allowed the conversion of 17.9% of the glucose substrate to ectoine. For the demand driven approach, we investigated the potential of the TeaBC transmembrane proteins from the ectoine-specific Tripartite ATP-Independent Periplasmic (TRAP) transporter as export channels to improve ectoine excretion. In the absence of the substrate-binding protein TeaA, an overexpression of both subunits TeaBC facilitated a three-fold increased excretion rate of ectoine. Individually, the large subunit TeaC showed an approximately five times higher extracellular ectoine concentration per dry weight compared to TeaBC shortly after its expression was induced. However, the detrimental effect on growth and ectoine titer at the end of the process hints toward a negative impact of TeaC overexpression on membrane integrity and possibly leads to cell lysis. By using either strategy, the ectoine synthesis and excretion in H. elongata could be boosted drastically. The inherent complementary nature of these approaches point at a coordinated implementation of both as a promising strategy for future projects in Metabolic Engineering. Moreover, a wide variation of intracelllular ectoine levels was observed between the strains, which points at a major disruption of mechanisms responsible for ectoine regulation in strain KB2.13.This work has been funded by the German Federal Ministry of Education and Research (BMBF) through project HOBBIT (031B03)

Adaptation to Varying Salinity in Halomonas elongata: Much More Than Ectoine Accumulation

The halophilic γ-proteobacterium Halomonas elongata DSM 2581 T thrives at salt concentrations well above 10 % NaCl (1.7 M NaCl). A well-known osmoregulatory mechanism is the accumulation of the compatible solute ectoine within the cell in response to osmotic stress. While ectoine accumulation is central to osmoregulation and promotes resistance to high salinity in halophilic bacteria, ectoine has this effect only to a much lesser extent in non-halophiles. We carried out transcriptome analysis of H. elongata grown on two different carbon sources (acetate or glucose), and low (0.17 M NaCl), medium (1 M), and high salinity (2 M) to identify additional mechanisms for adaptation to high saline environments. To avoid a methodological bias, the transcripts were evaluated by applying two methods, DESeq2 and Transcripts Per Million (TPM). The differentially transcribed genes in response to the available carbon sources and salt stress were then compared to the transcriptome profile of Chromohalobacter salexigens, a closely related moderate halophilic bacterium. Transcriptome profiling supports the notion that glucose is degraded via the cytoplasmic Entner-Doudoroff pathway, whereas the Embden-Meyerhoff-Parnas pathway is employed for gluconeogenesis. The machinery of oxidative phosphorylation in H. elongata and C. salexigens differs greatly from that of non-halophilic organisms, and electron flow can occur from quinone to oxygen along four alternative routes. Two of these pathways via cytochrome bo' and cytochrome bd quinol oxidases seem to be upregulated in salt stressed cells. Among the most highly regulated genes in H. elongata and C. salexigens are those encoding chemotaxis and motility proteins, with genes for chemotaxis and flagellar assembly severely downregulated at low salt concentrations. We also compared transcripts at low and high-salt stress (low growth rate) with transcripts at optimal salt concentration and found that the majority of regulated genes were down-regulated in stressed cells, including many genes involved in carbohydrate metabolism, while ribosome synthesis was up-regulated, which is in contrast to what is known from non-halophiles at slow growth. Finally, comparing the acidity of the cytoplasmic proteomes of non-halophiles, extreme halophiles and moderate halophiles suggests adaptation to an increased cytoplasmic ion concentration of H. elongata. Taken together, these results lead us to propose a model for salt tolerance in H. elongata where ion accumulation plays a greater role in salt tolerance than previously assumed

Deep-learning-based synthesis of post-contrast T1-weighted MRI for tumour response assessment in neuro-oncology:a multicentre, retrospective cohort study

International audienceBackground Gadolinium-based contrast agents (GBCAs) are widely used to enhance tissue contrast during MRI scans and play a crucial role in the management of patients with cancer. However, studies have shown gadolinium deposition in the brain after repeated GBCA administration with yet unknown clinical significance. We aimed to assess the feasibility and diagnostic value of synthetic post-contrast T1-weighted MRI generated from pre-contrast MRI sequences through deep convolutional neural networks (dCNN) for tumour response assessment in neuro-oncology. Methods In this multicentre, retrospective cohort study, we used MRI examinations to train and validate a dCNN for synthesising post-contrast T1-weighted sequences from pre-contrast T1-weighted, T2-weighted, and fluid-attenuated inversion recovery sequences. We used MRI scans with availability of these sequences from 775 patients with glioblastoma treated at Heidelberg University Hospital, Heidelberg, Germany (775 MRI examinations); 260 patients who participated in the phase 2 CORE trial (1083 MRI examinations, 59 institutions); and 505 patients who participated in the phase 3 CENTRIC trial (3147 MRI examinations, 149 institutions). Separate training runs to rank the importance of individual sequences and (for a subset) diffusion-weighted imaging were conducted. Independent testing was performed on MRI data from the phase 2 and phase 3 EORTC-26101 trial (521 patients, 1924 MRI examinations, 32 institutions). The similarity between synthetic and true contrast enhancement on post-contrast T1-weighted MRI was quantified using the structural similarity index measure (SSIM). Automated tumour segmentation and volumetric tumour response assessment based on synthetic versus true post-contrast T1-weighted sequences was performed in the EORTC-26101 trial and agreement was assessed with Kaplan-Meier plots. Interpretation Generating synthetic post-contrast T1-weighted MRI from pre-contrast MRI using dCNN is feasible and quantification of the contrast-enhancing tumour burden from synthetic post-contrast T1-weighted MRI allows assessment of the patient's response to treatment with no significant difference by comparison with true post-contrast T1-weighted sequences with administration of GBCAs. This finding could guide the application of dCNN in radiology to potentially reduce the necessity of GBCA administration

Hören, Sehen, Staunen. Zur Ideengeschichte der Interaktivität

Sofern man das Auftauchen und die stürmische Entwicklung der Computertechnologie mit positiven Utopien belegt hat, waren diese immer mit der Vorstellung einer `Befreiung des GeistesŽ verbunden. Was darunter zu verstehen ist, hat jedoch im Laufe der Zeit unterschiedliche Gestalt angenommen. Lange Zeit war in der Informatik ein Automatisierungsleitbild vorherrschend, und dementsprechend wollte man den Menschen von ,niederer' geistiger Arbeit entlasten und für seine eigentlichen Aufgaben freisetzen. Damit ergab sich natürlich auch immer die Frage, was diese denn sein sollten. Neben der durch das Automatisierungvorbild geprägten Leitlinie ist aber schon frühzeitig die alternative Vorstellung einer partnerschaftlichen Zusammenarbeit von Mensch und einer Maschine entstanden, welche ihn nicht ersetzt, sondern unterstützt. Diese Vorstellung ist immer eng mit den Möglichkeiten eines interaktiven Umgangs mit dem Computer verbunden gewesen. In diese Interaktion kann der Mensch seine kreativen Fähigkeiten einbringen und computerunterstützt zu ungeahnten Höhenflügen weiterentwickeln. Wie diese Interaktion zwischen Mensch und Maschine aussehen soll, welche Rolle dabei dem Computer zukommt, und wozu der Geist des Menschen befreit werden soll, hat jedoch im Laufe der Zeit unterschiedliche Ausprägungen erfahren. Ich will zu deren Betrachtung die Geschichte der Interaktivität in drei Phasen einteilen, die durch unterschiedliche Leitmetaphern geprägt sind. In der Anfangszeit wurde der interaktive Umgang mit dem Computer als eine Art Konversation vorgestellt, welche Mensch und Maschine zu einer Problemlöseeinheit verschmilzt. Mit der Verbreitung von PCs und Arbeitsplatzrechnern setzte sich die Vorstellung durch, daß man geistigeTätigkeiten ausführt, indem man auf deren graphischen Oberflächen Objekte manipuliert. Der konzentrierteste Ausdruck dieser Werkzeugvorstellung ist das Leitbild der `direkten ManipulationŽ. Heute befinden wir uns mitten in einer Phase, in der Software-Agenten die Bildschirme und Computernetze erobern. Dieser Entwicklung liegt die Vorstellung zugrunde, daß bei der Beschaffung und Produktion von Informationen die Delegation von mühseligen oder langweiligen Tätigkeiten an Agenten eine in vernetzten Zusammenhängen notwendig gewordene Entlastung bringt. Das Agentenkonzept ist so elektronischer Ausdruck einer Dienstleistungsgesellschaft

Compiler Supported Interval Optimisation for Communication Induced Checkpointing

There exist mainly three different approaches of checkpoint-based recovery mechanisms for distributed systems: coordinated checkpointing, uncoordinated checkpointing and communication induced checkpointing. It can be shown that communication induced checkpointing theoretically has the least minimum overhead, but also that the effective overhead depends on the communication behaviour and the resulting forced checkpoints. If the placement of checkpoints and the communication pattern is disadvantageous, the overhead can get arbitrary large due to a high number of forced checkpoints. We introduce a compiler supported approach to avoid unfavourable combinations of communication behaviour and local checkpoint placement. We analyse the application statically and prepare the placement of voluntary checkpoints. These placement decisions are reviewed during runtime. With this approach we optimise the effective checkpoint-intevals of voluntary and forced checkpoints and thus reduce the overhead of communication induced checkpointing