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To achieve the best treatment of mitral valve disease in a patient, surgeons aim to optimally combine complementary surgical techniques. Image-based in silico simulation as well as visualization of the mitral valve dynamics can support the visual analysis of the patient-specific valvular dynamics and enable an exploration of different therapy options. The usage in a time-constrained clinical environment requires a mitral valve model that is cost-effective, easy to set up, parameterize and evaluate. Working towards this goal, we develop a simplified model of the mitral valve and analyse its applicability for the sketched use-case. We propose a novel approach to simulate the mitral valve with position-based dynamics. The resulting mitral valve model can be deformed to simulate the closing and opening, and incorporate changes caused by virtual interventions in the simulation. Ten mitral valves were reconstructed from transesophageal echocardiogram sequences of patients with normal and abnormal physiology for evaluation. Simulation results showed good agreements with expert annotations of the original image data and reproduced valve closure in all cases. In four of five pathological cases, abnormal closing behaviour was correctly reproduced. In future research, we aim to improve the parameterization of the model in terms of biomechanical correctness and perform a more extensive validation., Computer Graphics Forum, 41 (1), ISSN:1467-8659, ISSN:0167-7055

We consider two most studied standard models in the theory of elasto-plasticity with hardening in arbitrary dimension $d\ge 2$, namely, the kinematic hardening and the isotropic hardening problem. While the existence and uniqueness of the solution is very well known, the optimal regularity up to the boundary remains an open problem. Here, we show that in the interior we have Sobolev regularity for the stress and hardening while for their time derivatives we have the "half" derivative with the spatial and time variable. This was well known for the limiting problem but we show that these estimates are uniform and independent of the order of approximation. The main novelty consist of estimates near the boundary. We show that for the stress and the hardening parameter, we control tangential derivative in the Lebesgue space~$L^2$, and for time derivative of the stress and the hardening we control the "half" time derivative and also spatial tangential derivative. Last, for the normal derivative, we show that the stress and the hardening have the $3/5$ derivative with respect to the normal and for the time derivative of the stress and the hardening we show they have the $1/5$ derivative with respect to the normal direction, provided we consider the kinematic hardening or near the Dirichlet boundary. These estimates are independent of dimension. In case, we consider the isotropic hardening near the Neumann boundary we shall obtain $W^{\alpha,2}$ regularity for the stress and the hardening with some $\alpha>1/2$ depending on the dimension and $W^{\beta,2}$ with some $\beta > 1/6$ for the time derivative of the stress and the hardening. Finally, in case of kinematic hardening the same regularity estimate holds true also for the velocity gradient.

Accurate quantification of nanoparticles (NPs) in complex media remains a considerable challenge when assessing the risk that manufactured nanoparticles pose for humans and environment. The radiolabeling of nanoparticles is a valuable tool for conducting lab-studies with realistic systems and realistically low NP concentrations. We have developed various methods of introducing radiotracers into some of the most common nanoparticles, such as Ag, carbon, SiO2, CeO2 and TiO2 nanoparticles. The labeling techniques are the synthesis of the nanoparticles using radioactive starting materials, the binding of the radiotracer to the nanoparticles, the activation of the nanoparticles using proton irradiation, the recoil labeling utilizing the recoil of a nuclear reaction to implant a radiotracer into the nanoparticle, and the in-diffusion of radiotracers into the nanoparticles at elevated temperatures. Using these methods we have produced [105/110mAg]Ag, [124/125/131I]CNTs, [48V]TiO2, [13/1419Ce]CeO2, [7Be]MWCNT, [64Cu]SiO2, [44/45Ti]TiO2, etc. for accurate quantification in complex media at environmentally relevant low concentrations. The nanoparticles labeled by our methods can be detected at minimal concentrations well in the ng/L range even with a background of the same element and without complicated sample preparations necessary. The methods are adaptable for a wide range of other nanoparticles. The labeled particles have been successfully used in release studies, environmental mobility studies, fate studies in waste water treatment and plant uptake studies.

Waste water treatment plants (WWTPs) represent an important step in the life cycle of manufactured nanomaterials. A considerable amount of nanoparticles (NPs) that are released from consumer products will end up in WWTPs, so that WWTPs can both serve as a potential end of life point for these nanoparticles, as well as a point of reentry into the environment via the WWTP effluents. It is thus of utmost importance to accurately quantify the fate of manufactured nanomaterials in waste water treatment in order to assess the risk We used the radiolabeling of nanoparticles to accurately quantify the distribution of nanoparticles between the effluents of a model waste water treatment plant. In order to achieve this TiO2 NP were radiolabeled with V-48 using proton irradiation at our cyclotron. Multi-wall carbon nanotubes (MWCNT) were radiolabeled with Be-7 via recoil at our cyclotron. CdSe/ZnS Quantum dots were radiolabeled with Zn-65 and Se-75 via radiosynthesis. The radiolabeled NPs were used in batch experiments and model waste water treatment plant experiments. The radiolabeling allowed us to quantify NP distribution between sludge and water phase in the WWTP and in the WWTP effluents. A distribution of about 10000 : 1 between sludge-associated NPs and free NPs in water is reached in the WWTP already shortly after injection of the NPs. Thus the elimination of the NPs from the WWTP is mainly controlled by the removal of surplus sludge taking place every day of operation. The NPs are eliminated from the WWTP with a half-life of about 6 days reflecting the pre-set sludge age. After about 22 days of operation 10 % of the initial NPs remain in the WWTP. Approximately 1 % of the NPs leave the WWTP via the cleared waste water, mainly associated with non-sedimented sludge particles, such that only about 1 ‰ of the NPs leave the WWTP as free particles via the cleared water. An impact of the NPs on the clearing process, as monitored by chemical oxygen demand of the inflow vs. the outflow, was not observed.

Correction to: Scientific Reports https://doi.org/10.1038/s41598-017-03693-x, published online 29 August 2017 The original version of this Article contained a typographical error in the spelling of the author V. Falk, which was incorrectly given as Falk. This has now been corrected in the PDF and HTML versions of the Article.