Evaluating the Suitability of 3D Bioprinted Samples for Experimental Radiotherapy: A Pilot Study

Radiotherapy is an important component in the treatment of lung cancer, one of the most common cancers worldwide, frequently resulting in death within only a few years of diagnosis. In order to evaluate new therapeutic approaches and compare their efficiency with regard to tumour control at a pre-clinical stage, it is important to develop standardized samples which can serve as inter-institutional outcome controls, independent of differences in local technical parameters or specific techniques. Recent developments in 3D bioprinting techniques could provide a sophisticated solution to this challenge. We have conducted a pilot project to evaluate the suitability of standardized samples generated from 3D printed human lung cancer cells in radiotherapy studies. The samples were irradiated at high dose rates using both broad beam and microbeam techniques. We found the 3D printed constructs to be sufficiently mechanically stable for use in microbeam studies with peak doses up to 400 Gy to test for cytotoxicity, DNA damage, and cancer cell death in vitro. The results of this study show how 3D structures generated from human lung cancer cells in an additive printing process can be used to study the effects of radiotherapy in a standardized manner.     

Die Entwicklung der orthotropen Fahrbahnplatte in Deutschland

Es wird die Entwicklung der orthotropen Platte von den ersten von Schaechterle und Leonhardt gestalteten Konstruktionen bis hin zu den konstruktiv und technologisch ausgereiften stählernen Fahrbahntafeln bei den neuesten stählernen Straßenbrücken der letzten Jahre beschrieben. Dabei werden insbesondere die im Entwicklungszeitraum angewendeten unterschiedlichen Rippenformen mit ihren Kreuzungspunkten an den Querträgern und die Ausführung der Montagestöße detailliert beschrieben. Technische Parameter der orthotropen Platte ausgeführter Stahlbrücken werden für torsionsweiche und torsionssteife Rippenformen tabellarisch getrennt erfasst. Schäden infolge Verkehrsbelastung und Fehler bei der Herstellung von orthotropen Platten werden erwähnt. The development of the orthotropic roadway‐plate in Germany. The development of the orthotropic plate beginning with the first of Schaechterle and Leonhardt created constructions till to the constructive and technological ingenious steel‐plates of the ultimate years is described. Especially the different types of ribs while the period of development inclusive the crosspoints at the crossbeams and their erection connections are special described. Technical parameter of the orthotropic plates of executed steel‐bridges are for ribs with and without torsional constant tabulated registered. Defects by traffic and faults by erection of the orthotropic plates are mentioned.     

On Smoothed Analysis of?Quicksort?and?Hoare’s Find

We provide a smoothed analysis of Hoare’s find algorithm, and we revisit the smoothed analysis of quicksort. Hoare’s find algorithm—often called quickselect or one-sided quicksort—is an easy-to-implement algorithm for finding the k-th smallest element of a sequence. While the worst-case number of comparisons that Hoare’s find needs is Θ(n ²), the average-case number is Θ(n). We analyze what happens between these two extremes by providing a smoothed analysis. In the first perturbation model, an adversary specifies a sequence of n numbers of [0,1], and then, to each number of the sequence, we add a random number drawn independently from the interval [0,d]. We prove that Hoare’s find needs $\Theta(\frac{n}{d+1} \sqrt{n/d} + n)$ comparisons in expectation if the adversary may also specify the target element (even after seeing the perturbed sequence) and slightly fewer comparisons for finding the median. In the second perturbation model, each element is marked with a probability of p, and then a random permutation is applied to the marked elements. We prove that the expected number of comparisons to find the median is $\Omega((1-p) \frac{n}{p} \log n)$ . Finally, we provide lower bounds for the smoothed number of comparisons of quicksort and Hoare’s find for the median-of-three pivot rule, which usually yields faster algorithms than always selecting the first element: The pivot is the median of the first, middle, and last element of the sequence. We show that median-of-three does not yield a significant improvement over the classic rule.     

Formation of discrete molecular size domains of melanoidins depending on the involvement of several α-dicarbonyl compounds: Part 2

The correlation of several α-dicarbonyl compounds with the melanoidin formation and their molecular size distribution was investigated. The results point out that α-dicarbonyl compounds, which were formed during the Maillard reaction, are not only the most important intermediates but also the direct precursors for carbohydrate-based melanoidins. Discrete molecular size domains are detected by size exclusion chromatography (SEC-DAD/RI), which were formed depending on the involvement of several α-dicarbonyls by thermal treatment of sucrose Maillard reaction solutions. By investigating sucrose Maillard reaction solutions spiked with methylglyoxal and 3-deoxyhexosulose carried on with direct melanoidin formation in aqueous solutions with α-dicarbonyls, molecular size domains of melanoidins could be connected for the first time with the reaction of several involved α-dicarbonyl compounds. High molecular size domains formed on the basis of methylglyoxal, whereas 3-deoxyhexosulose and d-glucosone promote lower molecular size domains. Concerning colour measurement methylglyoxal shows the highest browning activity followed by 3-deoxyhexosulose and d-glucosone. The reactivity of α-dicarbonyls and a correlated colour formation increase with rising alkaline pH-value. At a pH 5 the degradation and colour formation of α-dicarbonyl compounds is suppressed. The results provide new knowledge about colour formation in sucrose solutions. First part with the title, “Influence of α-dicarbonyl compounds to the molecular weight distribution of melanoidins in sucrose solutions: Part 1” was accepted in EFRT in January 2006. DOI: 10.1007/s00217-006-0277-1.     

Heat and mass transfer in wavy falling films of binary mixtures

Heat and mass transfer in an evaporating two-component falling liquid film are considered. Based on physical phenomena of the transport processes, models for the laminar and the turbulent-wavy falling film are presented. A comparison with experimental data shows that the laminar model is only applicable for restricted conditions. Predicted heat transfer coefficients of the turbulent-wavy model are compared with data from experiments with water and water–ethylene glycol as test fluid for Reynolds numbers between 250 and 420. The model predicts well the experimental data.