bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vanillin as low-temperature isocyanate-blocking agent and its use in one-component aqueous coatings
Authors: Knospe Philipp , Reichmann René , Gutmann Jochen S. , Dornbusch Michael 
Published: November 2022

AbstractMainly because of the high sensitivity of the isocyanate group to atmospheric moisture, it is blocked with a blocking agent for many applications and thus kept as inert as possible at room temperature (Zhang et al. in Langmuir ACS J Surf Colloids 37:12705, 2021, Meier-Westhues in Polyurethane: Lacke, Kleb-und Dichtstoffe, Vincentz Network, Hannover, p 36, 2007). When exposed to temperature, the protective group unblocks, and the isocyanate group reacts with the reactant that was previously present together with the blocked isocyanate (Meier-Westhues in Polyurethane: Lacke, Kleb- und Dichtstoffe, Vincentz Network, Hannover, p 36, 2007, Goldschmidt and Streitberger in BASF handbook on basics of coating technology, Vincentz Network, Hannover, pp 96–99, 2007). Many of the substances which are used today as blocking agents have toxicological concerns or unblock at high temperatures, which limits their application areas (Guillem Parra et al. in Blocked isocyanate polyurethane compositions using a new blocking agent, method of manufacture and uses thereof: European patent application, 2019, https://data.epo.org/publication-server/document?iDocId=6506253&iFormat=0). In this work, vanillin is presented as an effective deblocking agent at low temperatures and is compared with similar structures. The process of deblocking from an hexamethylene diisocyanate trimer (HDI-trimer) is followed by means of IR-spectroscopic measurements at different temperatures and thermogravimetric analysis. Temperature-dependent oscillation measurements using a rheometer are suitable for measuring onset temperatures and for qualitatively tracking the unblocking process. The combination of the results is used to draw conclusions about the existing deblocking mechanism. The comparatively low deblocking temperature of vanillin enables the formulation of an HDI-trimer modified with sulfonate groups and blocked with vanillin, which is dispersed in the aqueous phase and then reacted with OH-functional binders. Deblocking and subsequent reaction with the binder are followed by means of IR spectroscopy, and the mechanical properties of the coating films are examined. Vanillin is therefore suitable as a toxicologically harmless blocking agent for isocyanates and enables the production of crosslinkers for one-component water-based coatings (Arya et al. Adv Tradit Med (ADTM) 21:1, 2021).
Statistical optimization of the fermentation factors for increased biorefinery of corn-steep water effluent to lactic acid by Enterococcus faecium strain WH51-1
Authors: Selim Mohamed T. , Fouda Amr , Salem Salem S. , Abdel-Rahman Mohamed Ali 
Published: November 2022

AbstractOrganic
waste bioprocessing for production of useful products are increasing due to fossil fuel depletion, problems with waste management, and the requirement for biodegradable plastics. Lactic acid (LA) is important in foods, polymer beverages, cosmetics, and medicine applications. However, the main challenge in the large-scale processing of LA is the enhanced production and productivity using low-cost resources. In this study, Enterococcus faecium WH51-1, a newly obtained thermo-alkali tolerant LA bacterium, was used for LA production from corn-steep water (CSW) as raw material. The optimal culture conditions and medium components were established. Different concentrations of yeast extract (YE) and pH values were investigated with highest LA production of 48.2 ± 2.7 g/L at a yield of 0.89 ± 0.04 g/g-consumed sugars and a productivity of 0.50 ± 0.03 g/L.h at pH 8.5 without YE supplementation. A central composite design (CCD) was utilized to determine the high LA concentrations at optimal values for the process variables (sugar concentrations, temperature, inocula sizes, pH value, and YE concentration). The model was realized with an acceptable fit. The optimization of the factors was carried out by normal probability plots, interaction-plots, incorporating effect plots, analysis of variance (ANOVA), surface plots, Pareto charts, and contour plots. All the parameters were influenced at a 5% significance level. Additionally, some of the possible interactions between these parameters also influenced the production process. A regression model was suggested and fitted the experimental data very well. The results of this work investigated that LA synthesized of the optimized-fermentation conditions was 10% greater than classical optimization methods. This study presented a green “free nutrient” and cost-effective utilization of corn steep effluent as a cheap alternative substrate for biorefinery to lactic acid.
Graphical Abstract
On-farm experimentation practices and associated farmer-researcher relationships: a systematic literature review
Authors: Toffolini Quentin , Jeuffroy Marie-Hélène 
Published: November 2022

AbstractThe convergence among the rise of digital technologies, the attention paid to the localized issues of transitions in practices toward agroecology, and the emergence of new open innovation models are renewing and reviving the scientific community’s interest in on-farm experimentation (OFE). This form of experimentation is claimed to be enhanced by digital tools as well as being an enabler of production of credible, salient, and legitimate science insofar as it embraces a farmer-centric perspective. However, the forms of research in which some experimental activities on farms are anchored vary greatly, notably with regard to the actual forms that interventions on farms take, the legitimacy of the actors involved and their roles, or the observations and instruments applied for interpretation. We propose a systematic review of the literature and an analytical framework in order to better understand this diversity of practices behind on-farm experimentation. Our analysis segregated six major publication clusters based on themes appearing in titles and abstracts. These themes guided a more in-depth analysis of representative articles, from which we identified seven types of OFE practices that are described and discussed here with regard to the knowledge targeted, roles of the various actors, and on-farm experimental space. Our typology provides an original basis for supporting reflexivity and building alignment between the above-mentioned dimensions and the ways in which new tools can support the experimental process.
Multiple shell ejections on a 100 yr timescale from a massive yellow hypergiant
Authors: Oudmaijer René D. , Koumpia Evgenia 
Published: November 2022

AbstractThis contribution focuses on a rare example of the class of post-Red Supergiants, IRAS 17163-3907, the central star of the Fried Egg nebula. In particular, we discuss some of our recently published results in detail. The inner parts of the circumstellar environment of this evolved massive star are probed at milli-arcsec resolution using VLTI’s GRAVITY instrument operating in the K-band (2 µm), while larger, arcsecond, scales are probed by VISIR diffraction limited images around 10 µm, supplemented by a complete Spectral Energy Distribution. The spectro-interferometric data cover important diagnostic lines (Brγ, Na I), which we are able to constrain spatially. Both the presence and size of the Na i doublet in emission has been traditionally challenging to explain towards other objects of this class. In this study we show that a two-zone model in Local Thermal Equilibrium can reproduce both the observed sizes and strengths of the emission lines observed in the K-band, without the need of a pseudo-photosphere. In addition, we find evidence for the presence of a third hot inner shell, and demonstrate that the star has undergone at least three mass-loss episodes over roughly the past century. To explain the properties of the observed non-steady mass-loss we explore pulsation-driven and line-driven mass-loss and introduce the bi-stability jump as a possible underlying mechanism to explain mass-loss towards Yellow Hypergiants.
The impact of UV photons from a stellar companion on the chemistry of AGB outflows
Authors: Van de Sande M. , Millar T. J. 
Published: November 2022

AbstractBinary interaction with a stellar or planetary companion has been proposed to be the driving mechanism behind large-scale asymmetries, such as spirals and disks, observed within AGB outflows. We developed the first chemical kinetics model that takes the effect of a stellar companions’s UV radiation into account. The presence of a stellar companion can initiate a rich photochemistry in the inner wind. Its impact is determined by the intensity of the UV radiation and the extinction the radiation experiences. The outcome of the inner wind photochemistry depends on the balance between two-body reactions and photoreactions. If photoreactions dominate, the outflow can appear molecule-poor. If two-body reactions dominate, chemical complexity within the outflow can increase, yielding daughter species with a large inner wind abundance. A comprehensive view on the molecular content of the outflow, especially combined with abundance profiles, can point towards the presence of a stellar companion.
Circumbinary discs around post-AGB binaries as a result of binary interactions: an infrared interferometric view
Authors: Corporaal Akke , Kluska Jacques , Van Winckel Hans 
Published: November 2022

AbstractPost-Asymptotic Giant Branch (post-AGB) binary systems are binary interaction products. These stars have recently undergone a strong, but not well understood, binary interaction phase, leading to the formation of stable, compact circumbinary discs. These circumbinary discs are found to show many similar properties to protoplanetary discs around young stars. Here, we focus on one such system, namely IRAS 08544-4431 and resolve the inner regions of the complex circumstellar environment using multi-wavelength infrared interferometric techniques. The visibility data of PIONIER (H-band), GRAVITY (K-band), and MATISSE (L and N band) are analysed together using two families of geometric models, giving a good fit to all data.
Explaining the winds of AGB stars: Recent progress
Authors: Höfner Susanne , Freytag Bernd 
Published: November 2022

AbstractThe winds observed around asymptotic giant branch (AGB) stars are generally attributed to radiation pressure on dust, which is formed in the extended dynamical atmospheres of these pulsating, strongly convective stars. Current radiation-hydrodynamical models can explain many of the observed features, and they are on the brink of delivering a predictive theory of mass loss. This review summarizes recent results and ongoing work on winds of AGB stars, discussing critical ingredients of the driving mechanism, and first results of global 3D RHD star-and-wind-in-a-box simulations. With such models it becomes possible to follow the flow of matter, in full 3D geometry, all the way from the turbulent, pulsating interior of an AGB star, through its atmosphere and dust formation zone into the region where the wind is accelerated by radiation pressure on dust. Advanced instruments, which can resolve the stellar atmospheres, where the winds originate, provide essential data for testing the models.
Learning about AGB stars by studying the stars polluted by their outflows
Authors: Escorza Ana , De Rosa Robert J. 
Published: November 2022

AbstractA rich zoo of peculiar objects forms when Asymptotic Giant Branch (AGB) stars, undergo interactions in a binary system. For example, Barium (Ba) stars are main-sequence and red-giant stars that accreted mass from the outflows of a former AGB companion, which is now a dim white dwarf (WD). Their orbital properties can help us constrain AGB binary interaction mechanisms and their chemical abundances are a tracer of the nucleosynthesis processes that took place inside the former AGB star. The observational constraints concerning the orbital and stellar properties of Ba stars have increased in the past years, but important uncertainties remained concerning their WD companions. In this contribution, we used HD 76225 to demonstrate that by combining radial-velocity data with Hipparcos and Gaia astrometry, one can accurately constrain the orbital inclinations of these systems and obtain the absolute masses of these WDs, getting direct information about their AGB progenitors via initial-final mass relationships.
Long-term light curve variations of AGB stars: episodic mass-loss or binarity?
Authors: Ortiz Roberto , Jorissen Alain , Planquart Léa 
Published: November 2022

AbstractA significant fraction of the stars near the tip of the AGB phase become regular or semi-regular (Mira-type, SRs) pulsators. However, some of these light curves have shown intriguing secondary minima or sharp dips with much longer periods. Although this phenomenon shows some resemblance with the R CrB variables, the light curve is generally symmetric before and after the dip, whereas in R CrB the luminosity recovers slower after its minimum. More recently, high-resolution ALMA CO observations revealed a spiral structure around some of these stars, which suggests the presence of a stellar or sub-stellar companion. In these cases, the long-term light curve minima could be caused by periodic eclipses of the primary by a spiral circumstellar structure, and the long-period would be related to the orbital period. In this paper we discuss the pros and cons of the various proposed scenarios for the long-term minima of pulsating AGB stars.
BOSS-3D: A Binary Object Spectral Synthesis Code in 3D
Authors: Hennicker L. , Kee N. D. , Shenar T. , Bodensteiner J. , Abdul-Masih M. , El Mellah I. , Sana H. , Sundqvist J. O. 
Published: November 2022

AbstractTo decode the information stored within a spectrum, detailed modelling of the physical state is required together with accurate radiative transfer solution schemes. In the analysis of stellar spectra, the numerical model often needs to account for high velocity outflows, multi-dimensional structures, and the effects of binary companions. Focusing now on binary systems, we present the BOSS-3D spectral synthesis code, which is capable of calculating synthetic line profiles for a variety of binary systems. Assuming the state of the circumstellar material to be known, the standard pz-geometry is extended by defining individual coordinate systems for each object. By embedding these coordinate systems within the observer’s frame, BOSS-3D automatically accounts for outflows or discs within both involved systems, and includes all Doppler shifts. Moreover, the code accounts for different length-scales, and thus could also be used to analyse transit-spectra of planetary atmospheres. As a first application of BOSS-3D, we model the phase-dependent line profiles for the enigmatic binary (or multiple) system LB-1.
Getting started: How a supersonic stellar wind is initiated from a hydrostatic surface
Authors: Owocki Stan 
Published: November 2022

AbstractMost of a star’s mass is bound in a hydrostatic equilibrium in which pressure balances gravity. But if at some near-surface layer additional outward forces overcome gravity, this can transition to a supersonic, outflowing wind, with the sonic point, where the outward force cancels gravity, marking the division between hydrostatic atmosphere and wind outflow. This talk will review general issues with such transonic initiation of a stellar wind outflow, and how this helps set the wind mass loss rate. The main discussion contrasts the flow initiation in four prominent classes of steady-state winds: (1) the pressure-driven coronal wind of the sun and other cool stars; (2) line-driven winds from OB stars; (3) a two-stage initiation model for the much denser winds from Wolf-Rayet (WR) stars; and (4) the slow “overflow” mass loss from highly evolved giant stars. A follow on discussion briefly reviews eruptive mass loss, with particular focus on the giant eruption of η Carinae.
When Do Subpollen Particles Become Relevant for Ice Nucleation Processes in Clouds?
Authors: Werchner Sven , Gute E. , Hoose C. , Kottmeier Ch. , Pauling A. , Vogel H. , Vogel B. 
Published: November 2022

AbstractWhen exposed to sufficiently humid environments, pollen grains burst and release large quantities of small subpollen particles (SPPs) which carry ice nucleating macromolecules. In this study, for the first time we develop a physically based parameterization describing the bursting process of pollen by applying a turgor pressure parameterization and quantify the impact SPPs have on overall ice nucleation in clouds. SPPs are generated from simulated birch pollen emissions over Europe for a 10‐day case study in spring. We found SPP concentrations to surpass pollen grain concentrations by 4–6 orders of magnitude leading to an abundance of biological ice nuclei from SPPs in the range of 103−104 m−3. However, it is found that these concentrations lead to only small changes in hydrometeor number densities and precipitation. Addressing the question when SPPs become relevant for ice nucleation in clouds, we conducted a sensitivity investigation. We find that amplifying ice nucleation efficiency of biological particles by factors greater 100 increases the ice particle numbers by up to 25% (T ≈ 268 K). Strong reductions show in cloud droplet number concentration and water vapor at these temperatures while water vapor is increasing at 600 m. Overall, we found a net reduction of water in the atmosphere as liquid and particularly water vapor density is reduced, while frozen water mass density increases above 257 K. Findings indicate an alteration of mixed‐phase cloud composition and increased precipitation (up to 6.2%) when SPPs are considered as highly efficient biological ice nuclei.
A Generic Relation Between Turbidity, Suspended Particulate Matter Concentration, and Sediment Characteristics
Authors: Sehgal Dhruv , Martínez‐Carreras Núria , Hissler Christophe , Bense Victor F. , Hoitink A. J. F. (Ton) 
Published: November 2022

AbstractOptical turbidity sensors have become standard instrumentation to estimate suspended particulate matter concentration (SPMC). However, turbidity readings respond to factors other than SPMC, such as particle size and shape, organic fraction, sediment density and color. Therefore, local and site dependent calibrations are needed to transfer turbidity to SPMC. In this study, we propose a new relation between turbidity, suspended particulate matter (SPM) carbon content and particle size, which helps to move from local calibrations between turbidity and SPMC toward generic relations based on inherent SPM properties. Organic content is known to influence particle size, density and, as a result, turbidity, but an explicit formulation of turbidity accounting for organic content has not yet been established. We address this knowledge gap by collecting field data from four sites representing contrasting land use types, geological settings and watershed size. The sites were monitored with a turbidity meter, a LISST‐200X particle size analyzer and an automatic water sampler. SPM samples were collected and analyzed for particle size, carbon content, and color. Local calibrations between turbidity and SPMC derived at each site were compared with a generic calibration, where SPMC was obtained as a function of turbidity, carbon content, particle size and color. The mean relative error associated to predicted SPMCs was equal to 3% when using the generic calibration, which is only marginally lower than the mean relative error of 5% obtained using the local calibrations.
Limited Potential for Mineralization of Permafrost Peatland Soil Carbon Following Thermokarst: Evidence From Anoxic Incubation and Priming Experiments
Authors: Estop‐Aragonés Cristian , Heffernan Liam , Knorr Klaus‐Holger , Olefeldt David 
Published: November 2022

AbstractPermafrost thaw in peatlands risks emitting vast stores of soil organic carbon (SOC) as greenhouse gases to the atmosphere, yet anoxic conditions and low peat quality may prevent rapid SOC loss. To assess differences in anaerobic SOC mineralization following thaw and vulnerability of previously‐frozen peat, we incubated peat (5° and 14°C) from 15 depths of ⁓6 m cores from different thaw sites including an intact permafrost peat plateau and thermokarst bogs that thawed ∼30 and ∼200 years ago. Furthermore, a glucose‐addition experiment after >700 days assessed whether labile C inputs occurring following thermokarst could accelerate SOC mineralization (priming). We found a common pattern of SOC mineralization rate decreasing with depth and peat age. However, we found no differences in peat mineralization rates among sites for samples of similar age and of corresponding peatland developmental stage. Priming effects were minor and short‐term, and did not vary among sites or with peat developmental stage. We also found mineralization rates from anoxic incubations more than an order of magnitude higher than rates implied from field observations, suggesting mineralization rates from anaerobic incubations should be used mainly to interpret relative differences. Peat humification and peat nitrogen and phosphorous content explained more than 85% of the variability in mineralization rates. Peat quality did not influence the temperature sensitivity of peat mineralization. Overall, the absence of substantial priming effects and the lack of differences in mineralization rates between permafrost peat and peat thawed 200 years ago suggests that rapid peatland SOC loss following thaw is unlikely.
Analytic Approximations of Scattering Effects on Beam Chromaticity in 21‐cm Global Experiments
Authors: Rogers Alan E. E. , Barrett John P. , Bowman Judd D. , Cappallo Rigel , Lonsdale Colin J. , Mahesh Nivedita , Monsalve Raul A. , Murray Steven G. , Sims Peter H. 
Published: November 2022

AbstractScattering from objects near an antenna produce correlated signals from strong compact radio sources in a manner similar to those used by the “Sea Interferometer” to measure the radio source positions using the fine frequency structure in the total power spectrum of a single antenna. These fringes or ripples due to correlated signal interference are present at a low level in the spectrum of any single antenna and are a major source of systematics in systems used to measure the global redshifted 21‐cm signal from the early universe. In the Sea Interferometer a single antenna on a cliff above the sea is used to add the signal from the direct path to the signal from the path reflected from the sea thereby forming an interferometer. This was used for mapping radio sources with a single antenna by Bolton and Slee in the 1950s. In this paper we derive analytic expressions to determine the level of these ripples and compare these results in a few simple cases with electromagnetic modeling software to verify that the analytic calculations are sufficient to obtain the magnitude of the scattering effects on the measurements of the global 21‐cm signal. These analytic calculations are needed to evaluate the magnitude of the effects in cases that are either too complex or take too much time to be modeled using software.