Age Spreads and Systematics in λ Orionis with Gaia DR2 and the SPOTS Tracks

In this paper we investigate the robustness of age measurements, age spreads, and stellar models in young pre-main-sequence stars. For this effort, we study a young cluster, λ Orionis, within the Orion star-forming complex. We use Gaia data to derive a sample of 357 targets with spectroscopic temperatures from spectral types or from the automated spectroscopic pipeline in APOGEE Net. After accounting for systematic offsets between the spectral type and APOGEE temperature systems, the derived properties of stars on both systems are consistent. The complex interstellar medium, with variable local extinction, motivates a star-by-star dereddening approach. We use a spectral energy distribution fitting method calibrated on open clusters for the Class III stars. For the Class II population, we use a Gaia G-RP dereddening method, minimizing systematics from disks, accretion, and other physics associated with youth. The cluster age is systematically different in models incorporating the structural impact of starspots or magnetic fields than in nonmagnetic models. Our mean ages range from 2–3 Myr (nonmagnetic models) to 3.9 ± 0.2 Myr in the SPOTS model (f = 0.34). We find that star-by-star dereddening methods distinguishing between pre-main-sequence classes provide a smaller age spread than techniques using a uniform extinction, and we infer a minimum age spread of 0.19 dex and a typical age spread of 0.35 dex after modeling age distributions convolved with observed errors. This suggests that the λ Ori cluster may have a long star formation timescale and that spotted stellar models significantly change age estimates for young clusters.

Influence of the alkyl chain length on the physicochemical properties and microbial biocompatibility of phosphonium based fatty acid ionic liquids

Ionic liquids (ILs) have remarkable properties and applications in many areas of science. Phosphonium ILs have become important because of their unique chemical and thermal stabilities. The present work is focused on the synthesis, characterisation, physicochemical properties, and microbial toxicity assessment of phosphonium ILs bearing seven different fatty acid anions. The structures of the synthesised ILs were confirmed by 1H and 13C nuclear magnetic resonance (NMR) and FTIR spectroscopy. Physicochemical properties such as density and viscosity of pure ILs were measured at temperatures ranging from 298.15 to 313.15 K. The experimental density decreased, whereas the viscosity increased with an increasing number of carbon atoms in the anion. The derived properties were also found to be anion dependent. The thermal decomposition temperature was investigated by TGA. Subsequently, the toxicity profile of the ILs was determined for selected Gram positive and Gram negative bacteria and some species of fungi in terms of minimum inhibitory concentrations (MIC). The results show that the antimicrobial activities of the ILs are strongly related to the structures of the ILs, where an increase in toxicity was observed with increasing alkyl group chain length of the fatty acid anion.

Mars, a molecule archive suite for reproducible analysis and reporting of single molecule properties from bioimages

The rapid development of new imaging approaches is generating larger and more complex datasets revealing the time evolution of individual cells and biomolecules. Single-molecule techniques, in particular, provide access to rare intermediates in complex, multistage molecular pathways, but few standards exist for processing these information-rich datasets, posing challenges for wider dissemination. Here, we present Mars, an open-source platform for storage and processing of image-derived properties of biomolecules. Mars provides Fiji/ImageJ2 commands written in Java for common single-molecule analysis tasks using a Molecule Archive architecture that is easily adapted to complex, multistep analysis workflows. Three diverse workflows involving molecule tracking, multichannel fluorescence imaging, and force spectroscopy, demonstrate the range of analysis applications. A comprehensive graphical user interface written in JavaFX enhances biomolecule feature exploration by providing charting, tagging, region highlighting, scriptable dashboards, and interactive image views. The interoperability of ImageJ2 ensures Molecule Archives can easily be opened in multiple environments, including those written in Python using PyImageJ, for interactive scripting and visualization. Mars provides a flexible solution for reproducible analysis of image-derived properties facilitating the discovery and quantitative classification of new biological phenomena with an open data format accessible to everyone.

Refractive Indices of Aqueous Solutions of Isomeric Butylamines at 303.15 K: Experimental and Correlative Approach

Refractive indices () and densities (r) of water (W) + n-butylamine (NBA), + sec-butylamine (SBA) and + tert-butylamine (TBA) systems had been measured in the whole range of composition at 303.15 K, from which deviation in refractive index (DnD ) molar refraction (Rm) and excess molar refraction () had been evaluated. All of the derived properties were fitted to appropriate polynomials. DnD were fitted to the Redlich-Kister polynomial equation. Values of DnD were all positive and were all negative which were attributed to cross hydrogen bonding, specific interactions as well as interstitial accommodation effect. A comparative study of Lorentz-Lorenz (L-L), Weiner (W), Heller (H), Gladstone-Dale (G-D), Arago-Biot (A-B), Eykman (Eyk), Newton (Nw), Eyring-John (E-J) and Oster (Os) relations for determining the refractive index of a liquid had been carried out to test their validity for the three binaries over the entire mole fraction range of butylamines at 303.15 K.

A framework for quantifying uncertainty in DFT energy corrections

In this work, we demonstrate a method to quantify uncertainty in corrections to density functional theory (DFT) energies based on empirical results. Such corrections are commonly used to improve the accuracy of computational enthalpies of formation, phase stability predictions, and other energy-derived properties, for example. We incorporate this method into a new DFT energy correction scheme comprising a mixture of oxidation-state and composition-dependent corrections and show that many chemical systems contain unstable polymorphs that may actually be predicted stable when uncertainty is taken into account. We then illustrate how these uncertainties can be used to estimate the probability that a compound is stable on a compositional phase diagram, thus enabling better-informed assessments of compound stability.

Feldfrüchte und Strom von Agrarflächen: Was ist Agri-Photovoltaik und was kann sie leisten?

Agri-Photovoltaik bedeutet, dass Agrarflächen doppelt genutzt werden: zum Anbau von Feldfrüchten und zur Produktion von Strom. Aufgrund dieser ,,Doppelernte“ verliert die Landwirtschaft keine Anbauflächen ‐ anders als bei Photovoltaik-Freiflächenanlagen, die überwiegend der Stromerzeugung dienen. Damit Subventionen jenen Nutzungen zugute kommen, die der Umwelt und der Nahrungsmittelproduktion gleichermaßen dienen, ist es wichtig, Agri-Photovoltaik von Freiflächenanlagen abzugrenzen und verschiedene Varianten der Agri-Photovoltaik zu unterscheiden.“Agrivoltaics” denotes approaches to use agricultural areas simultaneously to produce food and to generate photovoltaic (PV) electricity. Social impact analysis shows that for a successful agrivoltaics dissemination, clear standards must be set for the agricultural activity on agrivoltaics sites, so that no subsidy abuse and pseudo-farming occur. Until today there is no internationally recognized definition of agrivoltaics, but since more governments are willing to include the technology in their policies, this article derives a generally valid agrivoltaics definition and puts it up for debate. In the first step, differentiation criteria of agrivoltaics from other PV applications were developed. In the second step, the derived properties were scrutinised with reference to the political reasons for agrivoltaics diffusion in Germany, and compared to Germany’s goals in terms of energy and environmental policy. Finally, a basic definition is derived that must meet certain mandatory requirements. This generally applicable definition of agrivoltaics can be supplemented in the national context by optional requirements to steer diffusion more purposefully. The results contribute to the debate on the definition of agrivoltaics in Germany and can also enrich the discourse in other governments and parliaments on agrivoltaics market introduction.

A Mathematical Investigation of a Continuous Covariance Function Fitting with Discrete Covariances of an AR Process

In this paper, we want to find a continuous function fitting through the discrete covariance sequence generated by a stationary AR process. This function can be determined as soon as the Yule–Walker equations are found. The procedure consists of two steps. At first the inverse zeros of the characteristic polynomial of the AR process must be fixed. The second step is based on the fact that an AR process can also be seen as a difference equation. By solving this difference equation, it is possible to determine a class of functions from which a candidate for a continuous covariance function can be determined. To analyze if this function is applicable as a positive definite covariance function, it is analyzed mathematically in view of the power spectral density compared to the characteristics of the power spectral density for the discrete covariances. Then it is shown that this function is positive semi-definite. At the end, a simulation of a stationary AR(3) process is elaborated to illustrate the derived properties.