In-depth rheological characterization of genetically modified xanthan-variants

Xanthan is an extensively studied viscosifying agent discovered in 1961. Acetylation and pyruvylation have a major influence on its rheological properties and the effect of these groups on the conformation and rheological properties of xanthan have been studied for decades. However, these studies rely mainly on chemical modifications and therefore the degree of pyruvylation and acetylation as well as regioselectivity of deacetylation cannot be controlled. Here, we present an in-depth rheological characterization of natural xanthan and seven xanthan-variants, with defined acetylation and pyruvylation patterns created via genetic modification of Xanthomonas campestris LMG 8031. By that approach xanthan-variants with defined acetylation and pyruvylation patterns in their most natural state due to the mild production conditions were obtained. It was possible to link the defined substituent patterns to their corresponding rheological properties to give novel structure-function relationship insights of xanthan-variants in salt-free environments and in the presence of mono- and divalent cations

Improving the inner surface state of thick-walled tubes by heat treatments with internal quenching considering a simulation based optimization

Internal Quenching is an innovative heat treatment method for difficult to access component sections. Especially, the microstructure, as well as the residual stress state at inner surfaces, of thick-walled tubes can be adjusted with the presented flexible heat treatment process. Based on multiphysical FE-models of two different steels, a simulative optimization study, considering different internal quenching strategies, was performed in order to find the optimal cooling conditions. The focus hereby was on the adjustment of a martensitic inner surface with high compressive residual stresses. The simulatively determined optimal cooling strategies were carried out experimentally and analyzed. A good agreement of the resulting hardness and residual stresses was achieved, validating the presented Fe-model of the Internal Quenching process. The shown results also indicate that the arising inner surface state is very sensitive to the transformation behavior of the used steel. Furthermore, the presented study shows that a preliminary simulative consideration of the heat treatment process helps to evaluate significant effects, reducing the experimental effort and time

Spinning Fast Iterative Data Flows

Parallel dataflow systems are a central part of most analytic pipelines for big data. The iterative nature of many analysis and machine learning algorithms, however, is still a challenge for current systems. While certain types of bulk iterative algorithms are supported by novel dataflow frameworks, these systems cannot exploit computational dependencies present in many algorithms, such as graph algorithms. As a result, these algorithms are inefficiently executed and have led to specialized systems based on other paradigms, such as message passing or shared memory. We propose a method to integrate incremental iterations, a form of workset iterations, with parallel dataflows. After showing how to integrate bulk iterations into a dataflow system and its optimizer, we present an extension to the programming model for incremental iterations. The extension alleviates for the lack of mutable state in dataflows and allows for exploiting the sparse computational dependencies inherent in many iterative algorithms. The evaluation of a prototypical implementation shows that those aspects lead to up to two orders of magnitude speedup in algorithm runtime, when exploited. In our experiments, the improved dataflow system is highly competitive with specialized systems while maintaining a transparent and unified dataflow abstraction.Comment: VLDB201

Adjuvant radiotherapy improves progression-free survival in intracranial atypical meningioma

BACKGROUND: Meningiomas are the most common primary tumors of the central nervous system. In patients with WHO grade I meningiomas no adjuvant therapy is recommended after resection. In case of anaplastic meningiomas (WHO grade III), adjuvant fractionated radiotherapy is generally recommended, regardless of the extent of surgical resection. For atypical meningiomas (WHO grade II) optimal postoperative management has not been clearly defined yet. METHODS: We conducted a retrospective analysis of patients treated for intracranial atypical meningioma at Charité Universitätsmedizin Berlin from March 1999 to October 2018. Considering the individual circumstances (risk of recurrence, anatomical location, etc.), patients were either advised to follow a wait-and-see approach or to undergo adjuvant radiotherapy. Primary endpoint was progression-free survival (PFS). RESULTS: This analysis included 99 patients with atypical meningioma (WHO grade II). Nineteen patients received adjuvant RT after primary tumor resection (intervention group). The remaining 80 patients did not receive any further adjuvant therapy after surgical resection (control group). Median follow-up was 37 months. Median PFS after primary resection was significantly longer in the intervention group than in the control group (64 m vs. 37 m, p = 0.009, HR = 0.204, 95% CI = 0.062-0.668). The influence of adjuvant RT was confirmed in multivariable analysis (p = 0.041, HR = 0.192, 95% CI = 0.039-0.932). CONCLUSIONS: Our study adds to the evidence that RT can improve PFS in patients with atypical meningioma

Evaluation of a luminometric cell counting system in context of antimicrobial photodynamic inactivation

Antimicrobial resistance belongs to the most demanding medical challenges, and antimicrobial photodynamic inactivation (aPDI) is considered a promising alternative to classical antibiotics. However, the pharmacologic characterization of novel compounds suitable for aPDI is a tedious and time-consuming task that usually requires preparation of bacterial cultures and counting of bacterial colonies. In this study, we established and utilized a luminescence-based microbial cell viability assay to analyze the aPDI effects of two porphyrin-based photosensitizers (TMPyP and THPTS) on several bacterial strains with antimicrobial resistance. We demonstrate that after adaptation of the protocol and initial calibration to every specific bacterial strain and photosensitizer, the luminometric method can be used to reliably quantify aPDI effects in most of the analyzed bacterial strains. The interference of photosensitizers with the luminometric readout and the bioluminescence of some bacterial strains were identified as possible confounders. Using this method, we could confirm the susceptibility of several bacterial strains to photodynamic treatment, including extensively drug-resistant pathogens (XDR). In contrast to the conventional culture-based determination of bacterial density, the luminometric assay allowed for a much more time-effective analysis of various treatment conditions. We recommend this luminometric method for high-throughput tasks requiring measurements of bacterial viability in the context of photodynamic treatment approaches

Influence of Electrode Structuring Techniques on the Performance of All-Solid-State Batteries

All-solid-state batteries (ASSBs) offer a promising route to safer batteries with superior energy density compared to conventional Li-ion batteries (LIBs). However, the design of the composite cathode and optimization of the underlying microstructure is one of the aspects requiring intensive research. Achieving both high energy and power density remains challenging due to limitations in ionic conductivity and active material loading. Using structure-resolved simulations, we investigate the potential of perforated and layered electrode designs to enhance ASSB performance. Design strategies showing significant performance increase in LIBs are evaluated regarding their application to ASSBs. Composite cathodes with solid electrolyte channels in the structure do not significantly increase cell performance compared to unstructured electrodes. However, the design with a two-layer cathode proves promising. The layered structure effectively balances improved ionic transport due to increased solid electrolyte fraction at the separator side and substantial active material loading through increased active material fraction at the current collector side of the cathode. Our research highlights key challenges in ASSB development and provides a clear direction for future studies in the field.Comment: 46 pages, 15 figure

Challenges Of Production Planning And Control For Powder Bed Fusion Of Metal With Laser Beam: A Perspective From The Industry

Due to technological advance, the Additive Manufacturing (AM) technology Powder Bed Fusion of Metal with Laser Beam (PBF-LB/M) is in widespread industrial use. PBF-LB/M offers the flexibility to generate different geometries in one build job independent of tools. Therefore, exploiting tool-dependent economies of scale is not required for efficient manufacturing of various complex geometries in small quantities. However, PBF LB/M production lines are capital intensive and include post-processing steps. Thus, high utilization and low work in process must be ensured to minimize costs, but reaching high utilization contradicts minimizing work in process and throughput time. In production planning and control (PPC), the trade-off between those production logistics key performance indicators (KPIs) is optimized. The advantage of flexibility to manufacture various geometries in one build job of PBF-LB/M comes with challenges for PPC. In this work, those challenges are analysed to derive implications for improvement, based on interviews with experts from the industry. Results show a need for PBF LB/M specific PPC. The need is higher the greater the technological control of PBF LB/M and the volume of a product program of a company are. Unlike for Conventional Manufacturing (CM), nesting and scheduling cannot be addressed separately in PPC for PBF LB/M. Thus, the optimization of production logistics KPIs is more complex due to more degrees of freedom. Combined with a typically shorter planning horizon for AM, this requires automated optimization software tools for combined nesting and scheduling. Currently, PPC that considers AM characteristics does not address CM steps in the post-process adequately, even though they cause a large proportion of effort and time. Furthermore, high automatization parallel to heterogenous manual tasks require a low number of workers with training in various skills