Studies on drug metabolism by fungi colonizing decomposing human cadavers. Part I: DNA sequence-based identification of fungi isolated from postmortem material

Cadavers can be colonized by a wide variety of bacteria and fungi. Some of these microbes could change the concentration or the metabolic pattern of drugs present in postmortem samples. The purpose of this study was to identify fungi from human postmortem material and to further assess their potential role in the metabolism of drugs. Aliquots of 252 postmortem samples (heart blood, liver, kidney, and lung) taken from 105 moderately to severely decomposed bodies were streaked on Sabouraud agar for isolation of fungal species. One part of the samples was worked up immediately after autopsy (group I). The second part had previously been stored at ?20 °C for at least 1 year (group II). Identification of the isolates was achieved morphologically by microscopy and molecularly by polymerase chain reaction amplification and sequencing of markers allowing species identification of the respective genera. Depending on the genus, different gene fragments were used: calmodulin for Aspergillus, β-tubulin for Penicillium, translation elongation factor 1α for Fusarium, and the internal transcribed spacer region of the ribosomal DNA for all remaining genera. A total of 156 fungal strains were isolated from 62 % of the postmortem materials. By using these primers, 98 % of the isolates could be identified to the species level. The most common genera were Candida (60.0 %—six species), Penicillium (10.3 %—two species), Rhodotorula (7.1 %—one species), Mucor (6.4 %—four species), Aspergillus (3.2 %—four species), Trichosporon (3.2 %—one species), and Geotrichum (3.2 %—one species). Group I samples contained 53 % more fungal species than stored samples suggesting some fungi did not survive the freezing process. The isolated fungi might be characteristic for decomposed bodies. The proposed methodology proved to be appropriate for the identification of fungi in this type of material.     

Parallel simulation of large scale multibody systems

Virtual prototyping plays an ever increasing role in the engineering disciplines. Nowadays, engineers can rely on powerful tools like object oriented modeling languages, e.g., Modelica. Models written in this language can be simulated by open source software as well as commercial tools. The advantage of this approach is that the engineers can concentrate themselves on modeling, whereas the numerical intricacies of the simulation are handled by the software. On the other hand the simulations are usually slower than implementations which are parallelized and optimized manually. This can lead to computation times which are infeasible in practice, e.g., when a real time simulation is necessary for a hardware-in-the-loop simulation. In this contribution we are concerned with speeding up such automated simulations by parallelization (on desktop hardware as well as HPC systems). We examine the parallelism across the system approaches. Additionally, the influence of the problem formulation on the simulation time is discussed. The implemented methods are demonstrated on engineering examples. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

pH Tuning of Water-Soluble Arylazopyrazole Photoswitches

Arylazopyrazoles are an emerging class of photoswitches with redshifted switching wavelength, high photostationary states, long thermal half-lives and facile synthetic access. Understanding pathways for a simple modulation of the thermal half-lives, while keeping other parameters of interest constant, is an important aspect for out-of-equilibrium systems design and applications. Here, it is demonstrated that the thermal half-life of a water-soluble PEG-tethered arylazo-bis(o-methylated)pyrazole (AAP) can be tuned by more than five orders of magnitude using simple pH adjustment, which is beyond the tunability of azobenzenes. The mechanism of thermal relaxation is investigated by thorough spectroscopic analyses and density functional theory (DFT) calculations. Finally, the concepts of a tunable half-life are transferred from the molecular scale to the material scale. Based on the photochromic characteristics of E- and Z-AAP, transient information storage is showcased in form of light-written patterns inside films cast from different pH, which in turn leads to different times of storage. With respect to prospective precisely tunable materials and time-programmed out-of-equilibrium systems, an externally tunable half-life is likely advantageous over changing the entire system by the replacement of the photoswitch.     

Polymer Transformers: Interdigitating Reaction Networks of Fueled Monomer Species to Reconfigure Functional Polymer States

Adaptivity is an essential trait of life. One type of adaptivity is the reconfiguration of a functional system states by correlating sensory inputs. We report polymer transformers, which can adaptively reconfigure their composition from a state of a mixed copolymer to being enriched in either monomer A or B. This is achieved by embedding and hierarchically interconnecting two chemically fueled activation/deactivation enzymatic reaction networks for both monomers via a joint activation pathway (network level) and an AB linker monomer reactive to both A and B (species level). The ratio of enzymes governing the individual deactivation pathways (our external signals) control the enrichment behavior in the dynamic state. The method shows high programmability of the reconfigured state, rejuvenation of transformation cycles, and quick in situ adaptation. As a proof‐of‐concept, we showcase this dynamic reconfiguration for colloidal surface functionalities.     

Dynamic light scattering method of polymer solutions

The main features of dynamic light scattering are briefly outlined. The capability of this method to characterizing molar mass distributions and to distinguishing different molecular architectures is demonstrated with some examples. Special attention is given to the question of internal mobility and the spectrum of relaxation times. Recent results on asymptotic behavior are presented and discussed. Scaling behavior of the first cumulant with respect of space and of the time correlation function with respect of time (shape function) is found. All examples studied so far demonstrate the dynamic scaling of Zimm-Rouse chains, but the prefactors strongly depend on branching and crosslinking.     

Comparison of irreversible and reversible cluster formation

Covalent and reversible cluster molecules were synthesized by an A₃B₂ type gelation. Crosslinking of three-arm hydroxyl-terminated star polymers with 2,4-toluenediisocyanate gave branched polymers, while the reversible analogue was made by crosslinking of tertiary amine-terminated star polymers with bis(4-hydroxy-3,5-dinitrophenyl) adipate. Gelation process was followed by static and dynamic light scattering. The extent of reacted groups was measured with UV spectroscopy. Growth of the covalent clusters could be described in terms of percolation scaling laws. The experimental gel point (P_{OH, cr} = 0.70) was shifted significantly from the theoretical predicted gel point (P_{OH, cr} = 0.50), indicating extensive ring formation during the gelation. The reversible endlinking reaction gave no macroscopic gelation, though increase of the cluster dimensions was observed. Ring formation proved to be an important side reaction in both cases; however, the ring formation ability seems to change in a different manner during the course of a gelation.