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Influences of different reduction temperatures on the microstructure and resulting internal stresses of (100) nickel oxide single crystal
No full textUnderstanding soil organic carbon dynamics in integrated crop-pasture systems: Insights into deep carbon
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Generalizability and transferability of machine learning models using hyperspectral reflectance data for maize traits
No full textHyperspectral reflectance provides rapid, non-destructive phenotyping of plant leaves. These data have been used to develop machine learning models for predicting diverse plant traits, yet key challenges remain. We collected hyperspectral reflectance data together with 25 anatomical, gas exchange, and chlorophyll fluorescence traits from 320 recombinant inbred lines grown over three seasons. Using these data, we systematically (1) compare the performance of PLSR and SVR across a wide range of traits, including also slow fluorescence kinetics, (2) assess model generalizability and transferability, and (3) investigate how different aggregation strategies affect predictive accuracy. Based on a nested cross-validation framework, single cross-validation with MSE as metric performed comparably to repeated cross-validation or PRESS-based calibration. Optimal performance of trait-specific predictions was found to be dependent on the combination of model and data aggregation levels. Structural and biochemical traits showed the best generalizability and transferability, whereas physiological traits, particularly those derived from gas exchange and fluorescence kinetics, exhibited markedly reduced transferability. Together, these results provide a rigorous benchmark for evaluating machine learning models for trait prediction from hyperspectral reflectance data, and highlight both the opportunities and limitations for achieving robust generalization across diverse environments and genotypes
Quasiparticle Effects and Strong Excitonic Features in Exfoliable 1D Semiconducting Materials
No full textWe report a first-principles study of the electronic and optical properties of recently identified one-dimensional semiconducting materials exfoliable from van der Waals-bonded bulk crystals. Specifically, we investigate four chalcogenide-based atomic chains, the covalently bonded S3 and Te3 chains, and polar-bonded As2S3 and Bi2Te3 chains, using a fully first-principles approach that combines density functional theory (DFT), density functional perturbation theory (DFPT), and many-body perturbation theory within the GW approximation and Bethe–Salpeter equation (BSE). Our vibrational analysis shows that the isolated, freestanding wires remain dynamically stable, with the zone-center optical phonon modes leading to infrared activity. The main finding of this study is the presence of very strong exciton binding energies (1–3 eV), which make these exfoliable 1D materials suitable platforms for room-temperature excitonic applications. Interestingly, the exciton character remains Wannier–Mott-like, as indicated by average electron–hole separations greater than the lattice constant. Notably, the optical gaps of these materials span a wide range ─ from infrared (0.8 eV, Bi2Te3), through the visible spectrum (yellow: 2.17 eV, Te3; blue: 2.71 eV, As2S3), up to ultraviolet (4.07 eV, S3) ─ highlighting their versatility for broadband optoelectronic applications. Our results offer a detailed, many-body perspective on the optoelectronic behavior of these low-dimensional materials and underscore their potential for applications in nanoscale optoelectronic devices
Giant Resonant Enhancement of Photoinduced Dynamical Cooper Pairing, far above T<sub>c</sub>
No full textPump-probe experiments performed on K3C60 have unveiled both optical and transport signatures of metastable light-induced superconductivity up to room temperature, far above Tc. Recent experiments have uncovered that excitation in the vicinity of 50meV enables the observation of high temperature light-induced superconductivity at significantly lower fluences. Inspired by these experiments we develop a mechanism which can explain such a giant resonant enhancement of light-induced superconductivity. Within a minimal non-linear Holstein model, we show that resonantly driving optical Raman modes leads to a time-dependent electron-phonon coupling. Such a coupling then modulates the effective electron-electron attraction, with the strongest modulations occurring when the drive is resonant with the phonon frequency. These dynamical modulations of the pairing interactions lead to Floquet-BCS instabilities at temperatures far exceeding equilibrium Tc, as observed in experiments. We conclude by discussing the implications of our general analysis on the K3C60 experiments specifically and suggesting experimental signatures of our mechanism
A 25 THz bandwidth THz spectroscopy system exploiting BNA crystals and a tunable single-ring-fiber pulse compressor
No full textWe present a terahertz time-domain spectroscopy (THz-TDS) system which accesses a broadband spectrum, efficiently covering the so-called "new THz gap" between 5 and 15 THz and extending beyond 25 THz. The system exploits nonlinear interactions within the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline) to generate and detect THz radiation upon excitation by a near-infrared (NIR) pulse centered at 1.03 um. To enable broadband THz spectral monitoring, the NIR pulse from a Yb-based solid-state laser undergoes spectral broadening in a gas-filled single-ring hollow-core photonic crystal fiber, followed by pulse compression to achieve durations as short as 31 fs. This approach paves the way for broadband spectroscopy in hard-to-access THz regions using widely available near-infrared ultrafast sources
Photoschaltbare Peptide als molekulare Werkzeuge zur Kodierung von Strukturordnung und -Unordnung in intrazellulären Aggregaten
No full textLong-distance transport of siRNAs with functional roles in pollen development
No full textSmall interfering RNAs (siRNAs) play a crucial role in plant reproduction, yet their mobility and function remain incompletely understood. We report that a large proportion of siRNAs found in pollen of Capsella rubella relies on mobile siRNAs from maternal sporophytic tissues, highlighting the importance of non-cell-autonomous siRNAs in male gametophyte development. Unlike tapetal siRNAs, which guide DNA methylation and require CLASSY3 and DNA-dependent RNA polymerase IV (Pol IV) activity in the tapetum, we found that Pol IV-dependent mobile siRNAs (PMsiRNAs) mainly function post-transcriptionally and do not guide DNA methylation. Nevertheless, PMsiRNAs share key features with tapetal siRNAs, including Pol IV dependency, clustering and a size range of 21–24 nucleotides. Using a grafting approach, we show that sporophytic Pol IV-dependent siRNAs act as non-cell-autonomous mobile signals that trigger PMsiRNA formation through post-transcriptional gene silencing. This process parallels reproductive phased siRNA biogenesis, which is widespread across angiosperms but has been considered absent in Brassicaceae. Loss of PMsiRNAs causes pollen arrest, underscoring their essential role. Together, these findings highlight siRNAs as long-distance communication signals from maternal sporophytic tissues to the male gametophyte with critical functions in developmental regulation