Silver Nanoparticle Fate and Accumulation in the Aquatic Food Web of Stream Microcosms

Silver nanoparticles (AgNPs) are used in 25% of all nano-enabled products and applied for anti-microbial properties. Silver nanoparticles are discharged into aquatic environments through wastewater discharge, runoff, and chemical spills. Once in aquatic environments silver nanoparticles have the potential to harm aquatic organisms. While the fate of silver nanoparticles in lentic systems has been investigated, limited information is available for the fate of silver nanoparticles in flowing environments. The purpose of this study was to compare the fate of AgNPs following a one-time pulsed application simulating a chemical spill, or small repetitive applications simulating effluent discharge, in artificial stream communities containing river water, sediment, periphyton, snails, and fish under realistic environmental conditions. In addition to comparing the fate of AgNPs between application types, the fate of AgNPs were also compared between 35 and 70 µg L-1 concentrations of AgNPs. Water samples were collected on days 0, 7, and 14 to quantify total Ag (TAg) in the water column. Periphyton samples were taken on days 0 and 14, and sediment, snail, and fish samples were taken on day 14 for silver content. Results from this study show that AgNP concentrations applied to streams only affects the fate of AgNPs in sediment where the majority of AgNPs settled and in fish which had limited exposure to AgNPs in the water column. Additionally, application type only affected the fate of AgNPs in periphyton samples of pulsed treated streams where snails and flowing conditions had a longer period of time to reduce Ag adsorption to periphyton compared to repetitively treated streams. In this study, silver nanoparticles rapidly settled in lotic environments placing benthic organisms at risk for Ag accumulation. Furthermore, exposure to 70 µg L-1 and 35 µg L-1 AgNPs concentrations in artificial streams was not toxic to aquatic organisms regardless of application type. This study emphasizes the importance of testing AgNP exposure under environmentally relevant conditions to assess their fate and toxicity in the environment

Large nuclear spin polarization in gate-defined quantum dots using a single-domain nanomagnet

The electron-nuclei (hyperfine) interaction is central to spin qubits in solid state systems. It can be a severe decoherence source but also allows dynamic access to the nuclear spin states. We study a double quantum dot exposed to an on-chip single-domain nanomagnet and show that its inhomogeneous magnetic field crucially modifies the complex nuclear spin dynamics such that the Overhauser field tends to compensate external magnetic fields. This turns out to be beneficial for polarizing the nuclear spin ensemble. We reach a nuclear spin polarization of ~50%, unrivaled in lateral dots, and explain our manipulation technique using a comprehensive rate equation model

Polaronic conductivity in the photoinduced phase of 1T-TaS2

The transient optical conductivity of photoexcited 1T-TaS2 is determined over a three-order-of-magnitude frequency range. Prompt collapse and recovery of the Mott gap is observed. However, we find important differences between this transient metallic state and that seen across the thermally-driven insulator-metal transition. Suppressed low-frequency conductivity, Fano phonon lineshapes, and a mid-infrared absorption band point to polaronic transport. This is explained by noting that the photo-induced metallic state of 1T-TaS2 is one in which the Mott gap is melted but the lattice retains its low-temperature symmetry, a regime only accessible by photo-doping.Comment: 10 pages, 4 figure

Oberflächen- und Tiefenmerkmale von Aufgaben in der Internationalen PhysikOlympiade

Wettbewerbsaufgaben sind, national wie international, zentraler Bestandteil naturwissenschaftlicher Schülerolympiaden, oder allgemeiner von Leistungstests, die vorgegebene Aufgaben in den Mittelpunkt stellen. Zu den Kernzielen der Wettbewerbsaufgaben gehören vor allem eine differenzierende Leistungsbeurteilung, die fachliche Weiterentwicklung und die Motivation der Teilnehmenden. Trotz der hohen Bedeutung der Aufgaben gibt es wenig systematisches Wissen darüber, was eine in diesem Sinne „gute” Wettbewerbsaufgabe ausmacht und in welcher Weise verwendete Aufgaben diese Kernziele erreichen. Im Rahmen des Auswahlwettbewerbs zur Internationalen PhysikOlympiade (IPhO) ist daher ein Projekt zur Untersuchung der diagnostischen Güte von Wettbewerbsaufgaben und Möglichkeiten zur Beurteilung ihrer Qualität begonnen worden. Dabei wird zum einen an Untersuchungen aus verschiedenen Wettbewerben und zum anderen an Erkenntnisse aus der Erforschung schwierigkeitsgenerierender Merkmale von Aufgaben in der Physik angeknüpft. Die Ergebnisse sollen genutzt werden, um bei der Entwicklung der Aufgaben an den aktuellen Forschungsstand anzuschließen und diese zukünftig stärker systematisiert voranzubringen. Dieser Beitrag gibt einen kurzen Überblick über die IPhO und stellt das skizzierte Projekt vor

Automatic Plane Pose Estimation for Cardiac Left Ventricle Coverage Estimation via Deep Adversarial Regression Network

Accurate segmentation of the ventricles plays a crucial role in determining cardiac functional parameters such as ventricular volume, ventricular mass, or ejection fraction. However, poor image quality, such as inadequate coverage of the left ventricle (LV) and right ventricle (RV) in cardiac magnetic resonance (CMR) image sequences, can significantly affect the assessment of cardiac function. This study investigates issues related to missing or corrupted imaging planes, which often lead to incomplete ventricle coverage. To address the challenge of estimating ventricle coverage in CMR images regardless of variations in imaging parameters such as device type, magnetic field strength, and protocol execution, we introduce a novel convolutional neural network (CNN) based on adversarial learning. Additionally, we integrate supplementary information (e.g., cross-view image data) as privileged information to enhance the interpretability of our model’s predictions and identify potential biases or inaccuracies. This research represents the first attempt to automatically estimate ventricular coverage by identifying missing slices and plane orientations in CMR images using a dataset-agnostic approach. The effectiveness of the proposed model is demonstrated through the evaluation of datasets from three diverse and sizable image acquisition cohorts, demonstrating superior performance compared to existing methods

Performance of absorption chillers in field tests

Absorption chillers can use waste heat, solar heat, or excess heat by cogeneration facilities to supply chilled water. Therefore, absorption chillers are important components for poly-generation, which can improve plant utilization and efficiency of the overall energy supply system. Currently, 27 new small and medium-scale (30–160 kW cooling capacity) absorption chillers with high efficiency in full- and part-load as well as low specific size and weight are the focus of two research projects sponsored by German Federal Ministries. The chillers are located in 20 different sites, four of them in Jordan and the rest in Germany. The main objective of these projects is to enhance trigeneration and solar cooling system efficiency. The Jordan projects and more than 70% of the German installations use dry cooling towers. Combined heat and power (CHP) plants or district heating grids provide the driving heat for regeneration at the German installations. Solar thermal collectors drive one German and all Jordan installations. Within the projects, the chillers are provided with an intelligent control algorithm that allows achieving several objectives at the same time. One of the objectives, of course, is to match the desired chilled water temperature as well as the cooling capacity. Another objective is, for instance, to fit the hot water outlet temperature. This is commonly essential in cogeneration to avoid emergency shutdowns of the CHP engine. The field operation shows that the deviation of said temperatures from the set point is usually less than ±0.5 K in operation. In those operational hours in which the temperatures of the heat source or heat sink do not allow to reach all objectives, a set of hierarchical aims can be established within the algorithm so that the chiller can be controlled to match its prioritized objectives. Furthermore, the designed absorption chiller performs dynamically and autonomously in a very large range of temperatures and flow rates. These can vary from 20% up to 150% of nominal conditions. This flexibility can be used to achieve up to 80% savings of electrical power consumption using speed-controlled pumps in part load conditions. In contrast to the common opinion that small and medium-scale absorption chillers are not competitive as compared to compression chillers, this paper shows applications in which absorption chillers are advantageous because of synergies with and multiple benefits within the rest of the energy supply system

Ecopreneurship fördern

Die Verbindung von Entrepreneurship und konsequenter Umweltorientierung begründet Ecopreneurship. Ecopreneure beeinflussen mit ihrem Unternehmen den Gesamtmarkt sowohl durch eine herausragende Umwelt- als auch Marktorientierung. Die Basis sind weniger Managementsysteme oder technische Verfahren als vielmehr persönliche Fähigkeiten, die entsprechend entwickelt werden sollten