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Entangled two-photon absorption (ETPA) could form the basis of nonlinear quantum spectroscopy at very low photon fluxes, since, at sufficiently low photon fluxes, ETPA scales linearly with the photon flux. When different pairs start to overlap temporally, accidental coincidences are thought to give rise to a "classical" quadratic scaling that dominates the signal at large photon fluxes and, thus, recovers a supposedly classical regime, where any quantum advantage is thought to be lost. Here, we scrutinize this assumption and demonstrate that quantum-enhanced absorption cross sections can persist even for very large photon numbers. To this end, we use a minimal model for quantum light, which can interpolate continuously between the entangled pair and a high-photon-flux limit, to analytically derive ETPA cross sections and the intensity crossover regime. We investigate the interplay between spectral and spatial degrees of freedom and how linewidth broadening of the sample impacts the experimentally achievable enhancement. [ABSTRACT FROM AUTHOR]

Miniaturized photoionization detectors (PIDs) are used in conjunction with gas chromatography systems to detect volatile compounds in gases by collecting the current from the photoionized gas analytes. PIDs should be inexpensive and compatible with a wide range of analyte species. One such PID is based on the formation of a He plasma in a dielectric barrier discharge (DBD), which generates vacuum UV (VUV) photons from excited states of He to photoionize gas analytes. There are several design parameters that can be leveraged to increase the ionizing photon flux to gas analytes to increase the sensitivity of the PID. To that end, the methods to maximize the photon flux from a pulsed He plasma in a DBD-PID were investigated using a two-dimensional plasma hydrodynamics model. The ionizing photon flux originated from the resonance states of helium, He(3P) and He(21P), and from the dimer excimer He2*. While the photon flux from the resonant states was modulated over the voltage pulse, the photon flux from He2* persisted long after the voltage pulse passed. Several geometrical optimizations were investigated, such as using an array of pointed electrodes. However, increasing the capacitance of the dielectric enclosing the plasma chamber had the largest effect on increasing the VUV photon fluence to gas analytes. [ABSTRACT FROM AUTHOR]

Both spontaneous Raman scattering and stimulated Raman scattering (SRS) are cornerstones of modern photonics, spectroscopy, and imaging. However, a unified understanding of the ultimate detectability of Raman scattering is lacking, due to both historical and technical reasons. Starting from quantum electrodynamics, we formulate the fundamental detectability for both spontaneous Raman scattering and SRS. The key concept is recognizing spontaneous Raman scattering as stimulated Raman process driven by vacuum field fluctuation. A simple and unified expression, Eq. (17), is derived, which can be depicted on a two-dimensional phase-diagram-like graph with inherent symmetry. It turns out that the particle nature of light dictates the ultimate detectability of spontaneous Raman scattering, which can be represented by a line on this detectability diagram. Importantly, if provided with a reasonably strong Stokes photon flux, SRS can breach this fundamental limit and open uncharted territory of drastically accelerated measurement speed and much lower detection concentration relevant to biological imaging. Such new territory in the detectability diagram is otherwise forbidden by the spontaneous counterpart. Diagrammatical analysis explains the empirical observations, provides quantitative insights, and makes new predictions. Notably, recent experimental applications of SRS microscopy can almost entirely be captured by this diagram, further supporting the explanatory power of the theory. Thus, this unified diagrammatic approach outlines a framework to understand all Raman-based measurement and provides a theoretical explanation for the remarkable utility of the emerging SRS microscopy. [ABSTRACT FROM AUTHOR]

We investigated the impact of carrier trapping on the carrier lifetime of metal halide perovskite materials, which are key to solar cell production. We examined NH3CH3PbI3 (MAPbI3), NH3CH3PbBr3 (MAPbBr3), and CsPbBr3 using continuous-wave (CW) laser illumination during microwave photoconductivity decay (μ-PCD) measurements. Traditional pulsed light excitation falls short of mirroring solar cell operating conditions, owing to carrier trapping. Implementing CW laser illumination provides a more accurate estimation of the carrier lifetimes under operational conditions. With an increased photon flux from the CW laser, the μ-PCD decay curves changed, indicating reduced recombination via traps. The experiments revealed extended carrier lifetimes under continuous light for the MAPbI3 polycrystal. This suggests that CW lasers can mitigate trapping effects on carrier lifetime measurements. For the other samples, carrier trapping had a negligible effect on the measured carrier lifetimes. We believe that these findings will aid in the design of perovskite-based devices. [ABSTRACT FROM AUTHOR]

High-energy photon interrogation is a nondestructive technique that is used to detect special nuclear materials and characterize nuclear waste. The development of such systems is complex and requires Monte Carlo simulations to optimize system performance. Monte Carlo simulations rely on various scattering, absorption, and photonuclear cross-section data. While the scattering and absorption cross-section data have been extensively studied and validated with experiments, the results obtained from photonuclear simulations are often found to underpredict measured results, indicating uncertainties in the photonuclear cross sections themselves. Thus, there is a need for new measured results that can be used to quantify underpredictions in simulations using photonuclear cross-section data. In the present work, we interrogated depleted uranium with a 9-MV electron linac and detected photoneutrons with trans-stilbene organic scintillators. The measurement of photoneutrons with organic scintillators is challenging due to the presence of the intense photon flux, which causes issues such as pulse pile-up, detector saturation, and poor signal-to-background ratio. To mitigate these challenges, we used iron and polyethylene shielding of varying thicknesses around the depleted uranium target and a neural network–based digital pulse processing algorithm to recover neutron and photon information from piled-up events. Our goal was to compare the measured photoneutron count rate with the simulated rate obtained using the MCNPX-PoliMi transport code. For a light output window of 0.28 to 2.67 MeVee (1.66- to 6.85-MeV proton recoil energy), we found that the simulated count rate obtained using the ENDF/B-VII photonuclear cross-section library underpredicts the measured rate by 32.8% $$ \pm $$ ± 3.2%. Additionally, we compared the simulated and measured photoneutron light output distributions. For the least thicknesses of shielding, the simulation was found to underpredict measurements in the 0.70- to 2.67-MeVee light output window. For the greatest thicknesses of shielding, the simulation was found to underpredict the measurement across the entire light output window of 0.28 to 2.67 MeVee. [ABSTRACT FROM AUTHOR]

Mid-wavelength infrared HgCdTe electron-initiated avalanche photodiodes (e-APDs) have presented excellent performances on resolving and counting photons. Aiming at low flux, the readout integrated circuit noise can be significantly reduced by certain device gain, and very low excess noise of HgCdTe e-APDs gives the opportunity for noise equivalent photon (NEPh) to be 1. Therefore, the main issue for signal-to-noise ratio of HgCdTe APD is gain normalized dark current density (GNDCD) at high reverse bias. In this work, the electric field distribution is optimized by designing the mesa device structure to suppress the tunneling current at high operating voltage. Furthermore, etching technology combining dry etching and wet etching and passivation technology based on plasma enhanced atomic layer deposition were used to reduce surface leakage current. Finally, 20 μm pitch 128 × 128 array HgCdTe APDs for cutoff wavelength 4.32 μm at 80 K corresponding to compositions xCd = 0.326 were fabricated, the measured GNDCD of the test unit is about 1.5–10 × 10−9 A/cm2 at 0–13 V, and very low excess noise guaranteed the NEPh to be 2.0 at gain = 93 and 1.6 at gain = 193. [ABSTRACT FROM AUTHOR]

Objective. A novel x-ray field produced by an ultrathin conical target is described in the literature. However, the optimal design for an associated collimator remains ambiguous. Current optimization methods using Monte Carlo calculations restrict the efficiency and robustness of the design process. A more generic optimization method that reduces parameter constraints while minimizing computational load is necessary. A numerical method for optimizing the longitudinal collimator hole geometry for a cylindrically-symmetrical x-ray tube is demonstrated and compared to Monte Carlo calculations. Approach. The x-ray phase space was modelled as a four-dimensional histogram differential in photon initial position, final position, and photon energy. The collimator was modeled as a stack of thin washers with varying inner radii. Simulated annealing was employed to optimize this set of inner radii according to various objective functions calculated on the photon flux at a specified plane. Main results. The analytical transport model used for optimization was validated against Monte Carlo calculations using Geant4 via its wrapper, TOPAS. Optimized collimators and the resulting photon flux profiles are presented for three focal spot sizes and five positions of the source. Optimizations were performed with multiple objective functions based on various weightings of precision, intensity, and field flatness metrics. Finally, a select set of these optimized collimators, plus a parallel-hole collimator for comparison, were modeled in TOPAS. The evolution of the radiation field profiles are presented for various positions of the source for each collimator. Significance. This novel optimization strategy proved consistent and robust across the range of x-ray tube settings regardless of the optimization starting point. Common collimator geometries were re-derived using this algorithm while simultaneously optimizing geometry-specific parameters. The advantages of this strategy over iterative Monte Carlo-based techniques, including computational efficiency, radiation source-specificity, and solution flexibility, make it a desirable optimization method for complex irradiation geometries. [ABSTRACT FROM AUTHOR]

Context. Determination of solar magnetic fields with a spatial resolution set by the diffraction limit of a telescope is difficult because the time required to measure the Stokes vector with sufficient signal-to-noise ratio is long compared to the solar evolution timescale. This difficulty becomes greater with increasing telescope size as the photon flux per diffraction-limited resolution element remains constant but the evolution timescale decreases linearly with the diffraction-limited resolution. Aims. We aim to improve magnetic field reconstruction at the diffraction limit without averaging the observations in time or space, and without applying noise filtering. Methods. The magnetic field vector tends to evolve more slowly than the temperature, velocity, or microturbulence. We exploit this by adding temporal regularisation terms for the magnetic field to the linear least-squares fitting used in the weak-field approximation, as well as to the Levenberg-Marquardt algorithm used in inversions. The other model parameters are allowed to change in time without constraints. We infer the chromospheric magnetic field from Ca II 854.2 nm observations using the weak field approximation and the photospheric magnetic field from Fe I 617.3 nm observations, both with and without temporal regularisation. Results. Temporal regularisation reduces the noise in the reconstructed maps of the magnetic field and provides a better coherency in time in both the weak-field approximation and Milne-Eddington inversions. Conclusions. Temporal regularisation markedly improves magnetic field determination from spatially and temporally resolved observations. [ABSTRACT FROM AUTHOR]

The development of a suitable irradiation setup is essential for in vitro experiments in photodynamic therapy (PDT). While various irradiation systems have been developed for PDT, only a few offer practical and high‐quality setups for precise and reproducible results in cell culture experiments. This report introduces a cost‐effective illumination setup designed for in vitro photodynamic treatments. The setup consists of a commercially available light‐emitting diode (LED) lamp, a cooling unit, and a specially designed 3D‐printed enclosure to accommodate a multiwell plate insert. The LED lamp is versatile, supporting various irradiation wavelengths and adjustable illumination fields, ensuring consistent and reliable performance. The study evaluates the setup through various parameters, including photon flux density, illumination uniformity, photon distribution across the multiwell plate, and temperature changes during irradiation. In addition, the effectiveness of the LED‐based illumination system is tested by treating mouse mammary breast carcinoma cells (4T1) with Rose Bengal and LED irradiation at around 525 nm. The resulting IC50 of 5.2 ± 0.9 μM and a minimum media temperature change of ca. 1.2°C indicate a highly promising LED‐based setup that offers a cost‐effective and technically feasible solution for achieving consistent, reproducible, and uniform irradiation, enhancing research capabilities and potential applications. [ABSTRACT FROM AUTHOR]

Photosynthesis under oblique illumination has not been studied extensively despite being the prevailing light regime under natural conditions. We studied how photosynthetic rate (An) is affected by the geometrical arrangement between leaf lamina and light rays, in conjunction with key anatomical features; studied plant species selected based on the absence (homobaric) or the occurrence of bundle sheath extensions (BSEs; heterobaric) and the arrangement of these structures, that is, parallel (monocots) or reticulated (dicots). The direction of light ray affected leaf absorptance (Abs) and An; both were maximal when the angle of incidence of light on leaf surface (polar angle, θ) was 90°. For any lower θ, both Abs and An were higher when the angle between the leaf axis and the light rays (azimuthal angle, φ) was zero. The dependence of Abs and An from φ was only evident in monocots and, especially, in heterobaric compared to homobaric leaves. In some species, An was substantially higher than predicted from calculated photon flux density of oblique light. The occurrence of BSEs, especially in monocots, significantly alters leaf optical properties, resulting in more efficient photosynthesis under oblique illumination conditions. Summary statement: Plant leaves harvest light for photosynthesis, usually, in a non‐perpendicular position related to the sun. Leaf anatomy increases light use efficiency under these conditions so that the rate of photosynthesis recorded is often much higher than predicted by optical geometry. [ABSTRACT FROM AUTHOR]

A high-flux beamline optimized for non-resonant X-ray emission spectroscopy (XES) in the tender X-ray energy range has been constructed at the BESSY II synchrotron source. The beamline utilizes a cryogenically cooled undulator that provides X-rays over the energy range 2.1 keV to 9.5 keV. This energy range provides access to XES [and in the future X-ray absorption spectroscopy (XAS)] studies of transition metals ranging from Ti to Cu (Kα, Kβ lines) and Zr to Ag (Lα, Lβ), as well as light elements including P, S, Cl, K and Ca (Kα, Kβ). The beamline can be operated in two modes. In PINK mode, a multilayer monochromator (E/ΔE ≃ 30-80) provides a high photon flux (1014 photons s-1 at 6 keV and 300 mA ring current), allowing non-resonant XES measurements of dilute substances. This mode is currently available for general user operation. X-ray absorption near-edge structure and resonant XAS techniques will be available after the second stage of the PINK commissioning, when a high monochromatic mode (E/ΔE ≃ 10000-40000) will be facilitated by a double-crystal monochromator. At present, the beamline incorporates two von Hamos spectrometers, enabling time-resolved XES experiments with time scales down to 0.1 s and the possibility of two-color XES experiments. This paper describes the optical scheme of the PINK beamline and the endstation. The design of the two von Hamos dispersive spectrometers and sample environment are discussed here in detail. To illustrate, XES spectra of phosphorus complexes, KCl, TiO2 and Co3O4 measured using the PINK setup are presented. [ABSTRACT FROM AUTHOR]

To effectively manage crop production in a greenhouse, it is essential to understand the natural light environment and physiological responses of the plants to light. This study investigated the dynamics of photosynthetic photon flux densities (PPFD) and light quality within the canopies of greenhouse-grown eggplant (Solanum melongena) and the photosynthetic capacities of leaves at different locations within the canopies. The light environment was quantified at 0.2-m intervals within (intracanopy) and adjacent to (extra-canopy) the crop canopy on both sunny and cloudy days within a commercial greenhouse located in Leamington, Ontario, Canada. Our results indicated a linear decline in extra-canopy PPFD on both sunny and cloudy days, but an exponential decrease in intra-canopy PPFD. The intra-canopy PPFD decreased by 91% and 76% between 0 m and 0.4 m from the canopy apex on sunny and cloudy days, respectively. The lower canopy (0.6–1.2 m) light spectrum consisted largely of far-red light, equal amounts of red light and green light, with a lower percentage of blue light. Parameters derived from leaf-level light response curves indicated that the light-saturated net carbon exchange rate, light saturation point, and light compensation point decreased as the distance from canopy apex increased, whereas quantum yield was unaffected. Thus, leaves in the lower canopy were less efficient at using high PPFD, but they displayed no deterioration of photosynthetic machinery. Based solely on photosynthetic capabilities, leaves between 0 and 1.0 m from the canopy apex should not be removed to decrease the total plant sink strength. [ABSTRACT FROM AUTHOR]

Understanding the origin of the diffuse flux of high-energy astrophysical neutrinos detected by IceCube has become a challenging issue within present High Energy Astrophysics. In this work, we present a model to explore the potential neutrino emission of starburst galaxies (SBG) by considering three different neutrino production zones that can be associated to a typical single SBG. The first zone is the starburst nucleus, where due to the high rate of supernova explosions, a significant amount of protons can be accelerated to high energies and undergo pp interactions with cold protons of the interstellar medium. The second zone we consider is the corresponding to the starburst wind, which is formed by the hot gas that emerges from the nucleus and interacts with the intergalactic medium generating shocks. Protons accelerated there can undergo pp interactions with the ambient matter. The third neutrino production zone we consider, is an external one, where we account for the possibility that protons escaping from the whole system interact with the cosmic microwave background. Finally, adding the neutrino contributions of the three zones, we calculate the diffuse neutrino flux and the diffuse photon flux by integration on the redshift range appropriate for SBG. We find that the model behaves well applied to nearby galaxies such as M82 and NGC 253. The contributions made to the diffuse neutrino flux are able to explain part of the data provided by IceCube if typical parameters are considered. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs), distinguished by their maximum atom efficiency and precise control over the coordination and electronic properties of individual atoms, show great promise in electrocatalysis. Gaining a comprehensive understanding of the electrochemical performance of SACs requires the screening of electron transfer process at micro/nano scale. This research pioneers the use of electrogenerated chemiluminescence microscopy (ECLM) to observe the electrocatalytic reactions at individual SACs. It boasts sensitivity at the single photon level and temporal resolution down to 100 ms, enabling real‐time capture of the electrochemical behavior of individual SACs during potential sweeping. Leveraging the direct correlation between ECL emission and heterogeneous electron transfer processes, we introduced photon flux density for quantitative analysis, unveiling the electrocatalytic efficiency of individual SACs. This approach systematically reveals the relationship between SACs based on different metal atoms and their peroxidase (POD)‐like activity. The outcomes contribute to a fundamental understanding of SACs and pave the way for designing SACs with diverse technological and industrial applications. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs), distinguished by their maximum atom efficiency and precise control over the coordination and electronic properties of individual atoms, show great promise in electrocatalysis. Gaining a comprehensive understanding of the electrochemical performance of SACs requires the screening of electron transfer process at micro/nano scale. This research pioneers the use of electrogenerated chemiluminescence microscopy (ECLM) to observe the electrocatalytic reactions at individual SACs. It boasts sensitivity at the single photon level and temporal resolution down to 100 ms, enabling real‐time capture of the electrochemical behavior of individual SACs during potential sweeping. Leveraging the direct correlation between ECL emission and heterogeneous electron transfer processes, we introduced photon flux density for quantitative analysis, unveiling the electrocatalytic efficiency of individual SACs. This approach systematically reveals the relationship between SACs based on different metal atoms and their peroxidase (POD)‐like activity. The outcomes contribute to a fundamental understanding of SACs and pave the way for designing SACs with diverse technological and industrial applications. [ABSTRACT FROM AUTHOR]

Benefiting from the development of high‐brilliance synchrotron radiation sources, microbeam X‐ray scattering has become a well established scattering‐based imaging technology. This article describes the newly constructed time‐resolved microbeam small‐angle X‐ray scattering (µSAXS) experimental station at the BL10U1 beamline at the Shanghai Synchrotron Radiation Facility. The µSAXS endstation provides SAXS/WAXS measurements with a 10 µm hard X‐ray beam and a flux of ∼1012 photons s−1. A multi‐axis sample stage, an on‐axis viewer and in situ experimental apparatus are incorporated to facilitate multi‐method scientific experiments in various material fields. As scientific examples, this article explores 1D tomography, 2D mapping and tomographic sectioning based on X‐ray scattering to investigate the micro–nanostructures of polymer fiber, spherulite and bamboo samples. [ABSTRACT FROM AUTHOR]

The development of simple and highly controllable fabrication methods for the β-Ga2O3, especially for the nanowire structure, has been a challenge. The slanted Ga2O3 nanowires are favorable for increasing the optical contact area and improving photon flux through nanoparticle scattering, leading to an increase in the photogenerated carrier yield. Herein, obliquely oriented and uniformly distributed β-Ga2O3 nanowires are fabricated on Si substrates by a radio frequency magnetron sputtering using the strategy of Au nanoparticles as an intermediate catalyst. By depositing Ti and Au electrodes, the metal-semiconductor-metal Ga2O3-based photodetectors are fabricated with a simple structure. Remarkably, the photodetector based on the β-Ga2O3 nanowires outperforms the one based on the β-Ga2O3 film, demonstrating higher responsivity and an exceptional photocurrent-to-dark current ratio (Iphoto/Idark) of 1.43 x 104 @5 V. This work presents a promising approach to enhance the utilization of incident light and maximize the generation of photoinduced carriers in the Ga2O3-based photodetectors. [ABSTRACT FROM AUTHOR]

In this work, we present an exact solution of phonon quasibound states in a vortex photon flow that creates an analogous black hole background. We worked out and successfully solve the governing differential equation of the systen that is similar with the relativistic Klein–Gordon equation. The exact radial solutions are discovered in terms of the confluent Heun functions that behaves as ingoing waves near the black hole's horizon and decaying far away from the black hole's horizon. The polynomial condition of the confluent Heun function leads to the discovery of the the complex valued quantized energy levels expression of the quasibound state of which depends on the phonon mass Ω 0 , the photon vortex horizon's spin Ω H and the azimuthal and the main quantum number (m, n). In the last section, by using the Damour–Ruffini method, the Hawking radiation of the analog black hole's horizon is investigated to derive the phononic radiation distribution function from where, the Hawking temberature is obtained. [ABSTRACT FROM AUTHOR]

Charge sensitive infrared phototransistors (CSIPs) show great promise for sensitive mid-infrared photodetection, extending up to single-photon counting, owing to the built-in amplification mechanism. However, the operating temperature of previously reported CSIPs has been limited to below 30 K. In this work, we propose a technique that enhances the operating temperature to above liquid nitrogen temperature by dynamically controlling the electrostatic potential of the optical floating gate (FG). This control effectively suppresses the annihilation of photogenerated holes in the FG, mitigating the vertical recombination process of thermally excited electrons. We detected the photosignal up to ∼85 K under a photon flux of Φ ∼ 3.6 × 10 8 s − 1 . An outstanding photoresponsivity (R = 39.11 A / W) to external blinking light at the peak wavelength of λ = 11 μm is achieved at 77 K. Our work not only extends the practical application of CSIPs, meeting the high demand for high temperature operation, but also offers more flexibility in fabricating more general highly sensitive phototransistors. [ABSTRACT FROM AUTHOR]

High redshift blazars are among the most powerful non-explosive sources in the Universe and play a crucial role in understanding the evolution of relativistic jets. To understand these bright objects, we performed a detailed investigation of the multiwavelength properties of 79 γ-ray blazars with redshifts ranging from z = 2.0 to 2.5, using data from Fermi LAT, Swift XRT / UVOT , and NuSTAR observations. In the γ-ray band, the spectral analysis revealed a wide range of flux and photon indices, from 5.32 × 10−10 to 3.40 × 10−7 photon cm−2 s−1 and from 1.66 to 3.15, respectively, highlighting the diverse nature of these sources. The detailed temporal analysis showed that flaring activities were observed in 31 sources. Sources such as 4C+71.07, PKS 1329-049, and 4C + 01.02, demonstrated significant increase in the γ-ray luminosity and flux variations, reaching peak luminosity exceeding 1050 erg s−1. The temporal analysis extended to X-ray and optical/ultraviolet (UV) bands, showed clear flux changes in some sources in different observations. The time-averaged properties of high redshift blazars were derived through modeling the spectral energy distributions with a one-zone leptonic scenario, assuming the emission region is within the broad-line region (BLR) and the X-ray and γ-ray emissions are due to inverse Compton scattering of synchrotron and BLR-reflected photons. This modeling allowed us to constrain the emitting particle distribution, estimate the magnetic field inside the jet, and evaluate the jet luminosity, which is discussed in comparison with the disc luminosity derived from fitting the excess in the UV band. [ABSTRACT FROM AUTHOR]

Shade stress is a common problem encountered in turfgrass management situations worldwide. Shade reduces photosynthetic photon flux (PPF), alters light quality, reduces air movement, and may introduce tree root competition. As a species, Kentucky bluegrass (Poa pratensis L.) possesses relatively poor shade tolerance, which limits its use in reduced light environments. However, genetic alteration of the gibberellic acid enzyme pathway has shown promise in some plant species for improving growth in shade. The objective of this 2‐year field study was to determine the comparative performance under reduced PPF and determine minimal daily light integral (DLIm) requirements for acceptable quality of a conventional (CONV) Kentucky bluegrass (KBG) blend and gibberellic acid 2‐oxidase (GA2ox) transformed "ProVista" (PV) KBG. A 2‐year field study was conducted under neutral density shade treatments producing monthly daily light integrals averaging from ∼5.8 (90% shade) to 48 mol m−2 day−1 (full sun) for mid‐June through October study periods. Based on nonlinear regression of mean monthly DLI during the study period versus turfgrass quality (TQ) at the end of each study period, DLIm was found to range from 7.5 to 10 mol m−2 day−1 for PV and from 22.5 to 26.2 mol m−2 day−1 for CONV KBG. Improved TQ of PV under low light intensities may be associated with reduced rates of leaf elongation, greater stand density, higher chlorophyll concentrations, and darker green color compared to CONV KBG. Although shade duration did not exceed 4 months, the results suggest that GA2ox‐transformed PV KBG possesses improved tolerance to reduced PPF compared to CONV KBG. Core Ideas: Limited data are available on minimal light requirements of Kentucky bluegrass cultivars.ProVista shows improved turf quality and color and reduced vertical regrowth relative to conventional under low photosynthetic photon flux.ProVista required minimal daily light integral of 7.5–10 mol m−2 day−1, while conventional Kentucky bluegrass requires 22–26 mol m−2 day−1. [ABSTRACT FROM AUTHOR]

Following the rapid growth in accelerator-based light sources research since the mid of 20th century, miscellaneous third generation synchrotron radiation (SR) facilities such as SSRL, APS, ESRF, PETRA-III, and SPring-8 have come into existence. These SR source facilities provide 1020–1025 photons/s/mrad2/mm2/0.1%BW peak brightness within the photon energy range of 10–105 eV. Since different measurement techniques are utilized at X-ray beamlines of SR facilities, many kinds of insertion devices (i.e., undulators and wigglers) and optical components (e.g., high-resolution monochromators, double-crystal monochromators, lenses, mirrors, etc.) are employed for each experimental setup as a matter of course. Under the circumstances, optimization of a synchrotron beamline is a big concern for many scientists to ensure required radiation characteristics (i.e., photon flux, spot size, photon energy, etc.) for dedicated user experiments. In this respect, an in-vacuum hybrid undulator driven by a 6 GeV synchrotron electron beam is optimized using evolutionary algorithms (EA). Finally, it is shown that EA results are well consistent with both the literature and the analytical calculations, resulting in a promising design estimation for beamline scientists. [ABSTRACT FROM AUTHOR]

Internal shocks are a leading candidate for the dissipation mechanism that powers the prompt γ-ray emission in gamma-ray bursts (GRBs). In this scenario a compact central source produces an ultra-relativistic outflow with varying speeds, causing faster parts or shells to collide with slower ones. Each collision produces a pair of shocks – a forward shock (FS) propagating into the slower leading shell and a reverse shock (RS) propagating into the faster trailing shell. The RS's lab-frame speed is always smaller, while the RS is typically stronger than the FS, leading to different conditions in the two shocked regions that both contribute to the observed emission. We show that optically thin synchrotron emission from both (weaker FS + stronger RS) can naturally explain key features of prompt GRB emission such as the pulse shapes, time evolution of the ν F ν peak flux and photon energy, and the spectrum. Particularly, it can account for two features commonly observed in GRB spectra: (i) a sub-dominant low-energy spectral component (often interpreted as 'photospheric'-like), or (ii) a doubly broken power-law spectrum with the low-energy spectral slope approaching the slow-cooling limit. Both features can be obtained while maintaining high-overall radiative efficiency without any fine tuning of the physical conditions. [ABSTRACT FROM AUTHOR]

Improving the efficiency of photosynthesis has important theoretical and practical value, and the application of pulsed light is an effective strategy for this goal. This study explored the theoretical temporal model of photosynthesis. In the experiment, the mean rate of oxygen evolution was measured under different photosynthetic photon flux densities and cycle durations with incremental pulse width modulation. The results revealed that the instantaneous oxygen evolution rate calculated using the differential method is an exponential curve, and a mathematical model was fitted. A photosynthetic capacitance model was proposed by referencing the capacitor charge circuit. The model suggests that a particular substance, which is stored in the photosynthetic capacitor, is consumed during the light period and accumulated during the dark period. This model could be used to explain the impact of the pulse parameters on the photosynthetic rate and provide new avenues for the study of photosynthesis under pulsed light to increase the photosynthetic rate. Oxygen evolution rate was measured using a new differential method. Temporal curve of photosynthetic rate was achieved by calculation. A capacitance model was proposed for photosynthesis under pulsed light. [ABSTRACT FROM AUTHOR]

Context. Galactic cosmic rays (CRs) play a crucial role in ionisation, dissociation, and excitation processes within dense cloud regions where UV radiation is absorbed by dust grains and gas species. CRs regulate the abundance of ions and radicals, leading to the formation of more and more complex molecular species, and determine the charge distribution on dust grains. A quantitative analysis of these effects is essential for understanding the dynamical and chemical evolution of star-forming regions. Aims. The CR-induced photon flux has a significant impact on the evolution of the dense molecular medium in its gas and dust components. This study evaluates the flux of UV photons generated by CRs to calculate the photon-induced dissociation and ionisation rates of a vast number of atomic and molecular species, as well as the integrated UV photon flux. Methods. To achieve these goals, we took advantage of recent developments in the determination of the spectra of secondary electrons, in the calculation of state-resolved excitation cross sections of H2 by electron impact, and of photodissociation and photoionisation cross sections. Results. We calculated the H2 level population of each rovibrational level of the X, B, C, B′, D, B″, D′, and a states. We then computed the UV photon spectrum of H2 in its line and continuum components between 72 and 700 nm, with unprecedented accuracy, as a function of the CR spectrum incident on a molecular cloud, the H2 column density, the isomeric H2 composition, and the dust properties. The resulting photodissociation and photoionisation rates are, on average, lower than previous determinations by a factor of about 2, with deviations of up to a factor of 5 for the photodissociation of species such as AlH, C2H2, C2H3, C3H3, LiH, N2, NaCl, NaH, O2+, S2, SiH, l-C4, and l-C5H. A special focus is given to the photoionisation rates of H2, HF, and N2, as well as to the photodissociation of H2, which we find to be orders of magnitude higher than previous estimates. We give parameterisations for both the photorates and the integrated UV photon flux as a function of the CR ionisation rate, which implicitly depends on the H2 column density, as well as the dust properties. [ABSTRACT FROM AUTHOR]

The influence of six experimental light sources (lamps) based on LEDs with different emission spectra simulating optical radiation close to solar radiation on the photochemical activity of photosystems (PS) of purple basil leaves and on the redox state of the P700 reaction center was studied. The spectra differed in the photon flux distribution over the main emission spectrum ranges, correlated color temperature (CCT), and general color rendering index (Ra). A comparative analysis of PAM fluorometry parameters resulted in the identification of the spectral regions that ensure more efficient photosynthetic processes in basil leaf cells at stages of technical ripening and flowering. In particular, basil plants grown on a spectrum with a CCT of 5260 K and Ra 98 had a fairly low F0 level, one of the highest Fv/Fm ratios characteristic of plants under nonstressful conditions, one of the highest quantum yields of both PS Y(I) and Y(II), and high electron flow rates. Spectra with CCT 4550 K and Ra 91 and with CCT 2820 K and Ra 81 also looked promising in terms of PAM fluorometry parameters. The spectrum with CCT 2990 and Ra 97 had the worst performance in terms of the studied PSI and PSII parameters. [ABSTRACT FROM AUTHOR]

This article provides an overview of the upgrade of the Swiss Light Source (SLS) synchrotron facility at the Paul Scherrer Institute in Switzerland. The upgrade, known as SLS 2.0, aims to improve the facility's performance by implementing new technologies such as multibend achromats and higher storage-ring energy. The article discusses the X-ray sources at SLS 2.0, including bending magnets and insertion devices, with innovations and upgrades being made for the undulators. The beamlines at SLS 2.0 are also undergoing changes, with upgrades in optics and the addition of new beamlines. The timeline for the project is provided, with full user operation expected after the completion of the upgrades. [Extracted from the article]

Recent technical developments and the performance of the X-ray photon correlation spectroscopy (XPCS) method over the ultra-small-angle range with the Extremely Brilliant Source (EBS) at the ESRF are described. With higher monochromatic coherent photon flux (~1012 photons s-1) provided by the EBS and the availability of a fast pixel array detector (EIGER 500K detector operating at 23000 frames s-1), XPCS has become more competitive for probing faster dynamics in relatively dilute suspensions. One of the goals of the present development is to increase the user-friendliness of the method. This is achieved by means of a Python-based graphical user interface that enables online visualization and analysis of the processed data. The improved performance of XPCS on the Time-Resolved Ultra-Small-Angle X-ray Scattering instrument (ID02 beamline) is demonstrated using dilute model colloidal suspensions in several different applications. [ABSTRACT FROM AUTHOR]

In this paper we report the detection of five strong gamma-ray bursts (GRBs) by the High-Energy Particle Detector (HEPD-01) mounted on board the China Seismo-Electromagnetic Satellite, operational since 2018 on a Sun-synchronous polar orbit at a ∼507 km altitude and 97° inclination. HEPD-01 was designed to detect high-energy electrons in the energy range 3–100 MeV, protons in the range 30–300 MeV, and light nuclei in the range 30–300 MeV n−1. Nonetheless, Monte Carlo simulations have shown HEPD-01 is sensitive to gamma-ray photons in the energy range 300 keV–50 MeV, even if with a moderate effective area above ∼5 MeV. A dedicated time correlation analysis between GRBs reported in literature and signals from a set of HEPD-01 trigger configuration masks has confirmed the anticipated detector sensitivity to high-energy photons. A comparison between the simultaneous time profiles of HEPD-01 electron fluxes and photons from GRB190114C, GRB190305A, GRB190928A, GRB200826B, and GRB211211A has shown a remarkable similarity, in spite of the different energy ranges. The high-energy response, with peak sensitivity at about 2 MeV, and moderate effective area of the detector in the actual flight configuration explain why these five GRBs, characterized by a fluence above ∼3 × 10−5 erg cm−2 in the energy interval 300 keV–50 MeV, have been detected. [ABSTRACT FROM AUTHOR]

Lettuce tipburn is a physiological disorder characterized by marginal necrosis and curling of inner, younger leaves caused by localized calcium deficiency, especially in low evapotranspiration environments that restrict mass flow and thus calcium mobility. Severe tipburn negatively affects the marketability and quality of greenhouse-grown hydroponic lettuce. We aimed to assess the effectiveness of a chemical-based, calcium-mobilizing biostimulant for mitigating lettuce tipburn when applied in hydroponic nutrient solutions. Butterhead lettuce (Lactuca sativa 'Rex') was grown indoors under warm-white light-emitting diodes at a mean photosynthetic photon flux density of 300 lmol-m22-s21 for 11 days. Subsequently, we transplanted seedlings into deep-water-culture hydroponic trays in a greenhouse at an air temperature of 24.6 ± 1.2 °C, relative humidity of 76.2% ± 7.4%, and 20-hour photoperiod with supplemental lighting from high-pressure sodium lamps. The plants were grown in nutrient solutions with and without the biostimulant codenamed CC US-2105 at two concentrations (22 and 220 lL-L21). Data were collected from plant samples at three harvests at 14, 21, and 28 days after transplant (DAT). At 14 DAT, there was no tipburn under any treatments. Compared with the control, the biostimulant at 22 lL-L21 increased shoot dry mass by 31%. At 21 DAT, the biostimulant at 220 lL-L21 eliminated tipburn, and the biostimulant increased shoot fresh weight by 28%, irrespective of the concentration. At 28 DAT, despite sufficient calcium in the whole plant and the remaining nutrient solution, severe tipburn still occurred in plants that did not receive the biostimulant (control). Compared with the control, the biostimulant at the higher concentration of 220 lL-L21 decreased the tipburn rating by 88% and the number of leaves with tipburn by 85%, increased the plant diameter by 11%, increased the total leaf number by six, and accumulated higher levels of manganese and zinc. In contrast, these parameters remained unaffected at the lower biostimulant concentration of 22 lL-L21. At 28 DAT, shoot biomass was unaffected by the biostimulant. In conclusion, the calcium-mobilizing biostimulant is an effective strategy to mitigate hydroponic lettuce tipburn without decreasing biomass accumulation in greenhouse conditions. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of diurnal and seasonal variations in photon flux density (PPFD) and air temperature on PSII efficiency in three sweet potato leaf-color cultivars: green (G), yellow-green (Y), and purple (P). The cultivars were exposed to full sunlight and measurements were taken from November to March. The maximal quantum yield of PSII photochemistry for the dark-adapted state (Fv/Fm) indicated Y's increased sensitivity to low temperatures at predawn, followed by G and P. Both quantum yield of PSII photochemistry for the dark and light- adapted state (ΔF/Fm') depressions were correlated with increased PPFD, with regression slopes in the order of Y > G > P. On high-light and low-temperature days, Fv/Fm values deviated below regression lines, with differences ranked as Y > G > P. These findings suggest that Y exhibits the highest sensitivity to high light and low temperatures, followed by G and then P in terms of PSII efficiency. [ABSTRACT FROM AUTHOR]

In this paper, we explore the noncommutative space–time to revive the idea that gamma-ray excess in the galactic center may stem from the annihilation of particle dark matter. In the noncommutative theory, the photon spectrum is produced by direct emission during this annihilation wherein a photon can be embed in the final state together with other direct products in new vertices. In the various configurations of dark matter phenomenology, we pursue the most prevalent model known as singlet scalar. Calculating the relevant aspects of the model and determining the parameters phase space, we derive the photon flux in the galactic center. This region, known for its high density and occasional existence of robust magnetic fields, serves as an ideal location for investigating theories that encompass the concept of Lorentz symmetry breaking. Upon comparing our numerical achievements with experimental data, it becomes evident that noncommutative space–time can be a reliable framework to explain the gamma-ray excess. [ABSTRACT FROM AUTHOR]

A quantitative simulation of a system of optical concentrators based on Winston's hexagonal cones, intended for the registration camera of the TAIGA-IACT Cherenkov gamma-ray telescope, has been performed. The data on the transmission of the cones are obtained; the distributions of the photon flux intensity in the plane of the detector are given. On the basis of the results obtained, an optimal configuration of optical concentrators is proposed, taking into account the design features of the mount, mirror and TAIGA-IACT camera, as well as the features of its new detector units. [ABSTRACT FROM AUTHOR]

A new method for the synthesis and deposition of tungsten oxide nanopowders directly on the surface of a carbon-fiber-reinforced polymer composite (CFRP) is presented. The CFRP was chosen because this material has very good thermal and mechanical properties and chemical resistance. Also, CFRPs have low melting points and are transparent under ionized radiation. The synthesis is based on the direct interaction between high-power-density microwaves and metallic wires to generate a high-temperature plasma in an oxygen-containing atmosphere, which afterward condenses as metallic oxide nanoparticles on the CFRP. During microwave discharge, the value of the electronic temperature of the plasma, estimated from Boltzmann plots, reached up to 4 eV, and tungsten oxide crystals with a size between 5 nm and 100 nm were obtained. Transmission electron microscopy (TEM) analysis of the tungsten oxide nanoparticles showed they were single crystals without any extended defects. Scanning electron microscopy (SEM) analysis showed that the surface of the CFRP sample does not degrade during microwave plasma deposition. The X-ray attenuation of CFRP samples covered with tungsten oxide nanopowder layers of 2 µm and 21 µm thickness was measured. The X-ray attenuation analysis indicated that the thin film with 2 µm thickness attenuated 10% of the photon flux with 20 to 29 KeV of energy, while the sample with 21 µm thickness attenuated 60% of the photon flux. [ABSTRACT FROM AUTHOR]

Plant biomass production (BP), nitrogen uptake (Nup) and their ratio, and nitrogen use efficiency (NUE) must be quantified to understand how nitrogen (N) cycling constrains terrestrial carbon (C) uptake. But the controls of key plant processes determining Nup and NUE, including BP, C and N allocation, tissue C:N ratios and N resorption efficiency (NRE), remain poorly known.We compiled measurements from 804 forest and grassland sites and derived regression models for each of these processes with growth temperature, vapour pressure deficit, stand age, soil C:N ratio, fAPAR (remotely sensed fraction of photosynthetically active radiation absorbed by green vegetation) and growing‐season average daily incident photosynthetic photon flux density (gPPFD; effectively the seasonal concentration of light availability, which increases polewards) as predictors. An empirical model for leaf N was based on optimal photosynthetic capacity (a function of gPPFD and climate) and observed leaf mass per area. The models were used to produce global maps of Nup and NUE.Global BP was estimated as 72 Pg C/year; Nup as 950 Tg N/year; and NUE as 76 g C/g N. Forest BP was found to increase with growth temperature and fAPAR and to decrease with stand age, soil C:N ratio and gPPFD. Forest NUE is controlled primarily by climate through its effect on C allocation—especially to leaves, being richer in N than other tissues. NUE is greater in colder climates, where N is less readily available, because below‐ground allocation is increased. NUE is also greater in drier climates because leaf allocation is reduced. NRE is enhanced (further promoting NUE) in both cold and dry climates.Synthesis. These findings can provide observationally based benchmarks for model representations of C–N cycle coupling. State‐of‐the‐art vegetation models in the TRENDY ensemble showed variable performance against these benchmarks, and models including coupled C–N cycling produced relatively poor simulations of Nup and NUE. [ABSTRACT FROM AUTHOR]

This study examined the photochemical transformation of an oxazolone derivative in a continuous microreactor irradiated by a UVC LED array (273 nm). The aim of this study was to transfer the reaction protocol originally developed under batch conditions to continuous flow and to further evaluate the scope of this application. A custom-built UVC-LED panel was combined with a microchip, and this microflow system allowed to work under perfectly controlled operating conditions. NMR and LC-MS were used to identify and quantify the main products obtained during the reaction. From this, an HPLC method was developed for imine separation, allowing for an easy and fast monitoring of the reaction progress. Subsequently, the influence of the operating conditions (residence time, photon flux density, temperature) on the selectivity and conversion was investigated to identify the most favorable conditions for a specific product. Temperature did not affect conversion but had an impact on the reaction's selectivity. The developed UVC-LED-driven continuous-flow microreactor was found to be very efficient since a quantum photon balance ratio of 0.7 was enough to convert all the reactant, while at the same time achieving the maximal yield of the target product. Exhaustive irradiation did not change the molar ratio of each compound present in the reaction medium, thus excluding follow-up photoreactions of the products. This work opens promising perspectives for boosting flow photochemistry in the UV-C domain. [ABSTRACT FROM AUTHOR]

The main objective of this study was to characterize intumescence injury of three susceptible tomato cultivars grown in a greenhouse or indoors using two types of soilless culture systems. Plants of cultivars Maxifort, Camaro, and Patio were grown in either an indoor environment with broadband white and red light-emitting diode (LED) fixtures providing a daily light integral (DLI) of 12.7 mol·m-2·day-1 [photosynthetic photon flux density (PPFD) of 220 ± 3 mmol·m-2·s-1 for 16 h·d-1] or in a glass-glazed greenhouse with supplemental lighting provided by high-pressure sodium lamps that delivered a PPFD of ~150 μmol·m-2·s-1. Plants were grown using deep-water culture hydroponic systems or containers with a peat-based substrate. The growing environment had a larger effect on intumescence incidence and severity than the growing system, likely due to differences in ultraviolet radiation (100 to 400 nm), but other factors such as day/night temperature and relative humidity (RH), could have affected the response. Across cultivars, the probability of developing intumescence was higher indoors (>91%) than in the greenhouse. Indoor-grown plants also developed symptoms of the disorder from 2 to 6 days earlier than those in the greenhouse. Similarly, intumescence incidence was higher in plants from all cultivars grown indoors than in the greenhouse, but differences between the two environments were generally greater for Patio and Camaro than for Maxifort, which was the most susceptible cultivar. Greenhouse conditions were more conducive to active plant growth. For example, plants in the greenhouse were more than 2 times taller and had at least 12 times greater leaf area than those indoors, which resulted in large differences in shoot dry mass. However, environmental effects on intumescence response also contributed to differences in growth, as plants that were most affected by the disorder experienced severe leaf abscission and/or senescence. Our overall findings show that intumescence is greatly affected by the production environment, but injuries are likely to change based on genetic susceptibility. [ABSTRACT FROM AUTHOR]

A study of the activity of a bright M-dwarf L 98-59, located at a distance of 10.6 pc from Earth is reported. The star has a multiplanetary system, where one of the planets, L 98-59 b, is a rocky planet with a mass not exceeding the mass of Venus. It was found that the level of chromospheric activity of L 98-59 does not exceed the average value characteristic of other cold dwarfs with similar color index values . This level is below solar, the mean parameter for L 98-59 is equal to 5.297 dex. The data about the parent star and its activity was used to estimate the magnitude of the atmospheric escape of five planets (including the planet candidate 05). To calculate the loss of matter from the planetary atmospheres (without a detailed modeling of the processes in the "star–planet" system), we applied an approximation formula corresponding to the energy-limited atmospheric loss model. Estimates of the XUV photon flux—extreme ultraviolet (EUV) and X-ray photons for the medium and high activity levels, as well as the estimates of the tidal parameter were found. Variations of the parameter have been specified for five planets of the L 98-59 system, taking into account the possible activity level variations of the star. The parameter variations for planets c–e range from g s to g s (average activity level) and – g s (high activity level). For the planet L 98-59 b, the an analogue of Venus, we got the following estimates: and g s (for the intermediate and high activity levels, respectively). It can be assumed that the relatively modest outflow of matter from their atmospheres , despite the proximity of the planets to their star, is due to a small flux of XUV photons from the star due to the low level of its activity. [ABSTRACT FROM AUTHOR]

Phycoerythrin (PE) is a photosensitive red pigment from phycobiliprotein family predominantly present in the red algae. The concentration of PE depends on photon flux density (PFD) and the quality of light absorbed by the algae tissue. This necessitates robust techniques to extract PE from the embedded cell-wall matrix of the algal frond. Similarly, PE is sensitive to various factors which influence its stability and purity of PE. The PE is extracted from Red algae through different extraction techniques. This review explores an integrative approach of fractionating PE for the scaling-up process and commercialization. The mechanism for stabilizing PE pigment in food was critically evaluated for further retaining this pigment within the food system. The challenges and possibilities of employing efficient extraction for industrial adoption are meticulously estimated. The techniques involved in the sustainable way of extracting PE pigments improved at a laboratory scale in the past decade. Although, the complexity of industrial-scale biorefining was found to be a bottleneck. The extraction of PE using benign chemicals would be safe for food applications to promote health benefits. The precise selection of encapsulation technique with enhanced sensitivity and selectivity of the membrane would bring better stability of PE in the food matrix. [ABSTRACT FROM AUTHOR]

Fermi -Large Area Telescope (LAT) observations provide continuous and regularly sampled measurements of gamma-ray photon flux for hundreds of blazars. Many of these light curves, spanning almost 15 yr, have been thoroughly examined for periodicity in multiple studies. However, the possibility that blazars may exhibit irregularly repeating flaring patterns in their gamma-ray light curves has not been systematically explored. In this study, we aim to find repeating episodes of flaring activity in the 100 brightest blazars using Fermi-LAT light curves with various integration times. We use a Bayesian Blocks representation to convert the time series into strings of symbols and search for repeating sub-strings using a fuzzy search algorithm. As a result, we identify 27 repeated episodes in the gamma-ray light curves of 10 blazars. We find that the patterns are most likely produced in structured jets composed of a fast spine and a slower sheath. When individual emission features propagate in the spine, they scatter seed photons produced in the non-uniform sheath through the inverse Compton mechanism, resulting in a set of gamma-ray flares with a similar profile every such passage. Additionally, we explore the theoretically predicted possibility that the spine-sheath structure facilitates the production of high-energy neutrinos in blazar jets. Using the catalogue of track-like events detected by the IceCube neutrino telescope, we find evidence supporting this hypothesis at a 2.8σ significance level. [ABSTRACT FROM AUTHOR]

N 157B located in the Large Magellanic Cloud is the first pulsar wind nebula detected outside of the Galaxy in γ-rays. In this paper, we analyse the emission above 30 GeV from N 157B using ∼14.3 yr of Fermi -LAT data. The γ-ray spectrum between 30 and 500 GeV is well described by a single power-law function with a photon index of 1.83 ± 0.26, and its integral photon flux is (4.10 ± 0.83) × 10−11 photons cm−2 s−1. We adopt a one-zone leptonic model to investigate whether the multiband non-thermal emission of the target source can be generated by synchrotron radiation and inverse-Compton scattering of the electrons/positrons. Assuming the electrons/positrons in the nebula have a broken power-law spectrum with two breaks, the model can reproduce the observed fluxes in the radio, X-ray, and γ-ray bands. This result indicates that the γ-ray emission from N 157B can be explained by the leptonic process of electrons/positrons via inverse-Compton scattering. [ABSTRACT FROM AUTHOR]

The SAXSMAT beamline P62 (Small-Angle X-ray Scattering beamline for Materials Research) is a new beamline at the high-energy storage ring PETRA III at DESY. This beamline is dedicated to combined small- and wide-angle X-ray scattering (SAXS/WAXS) techniques for both soft and hard condensed matter systems. It works mainly in transmission geometry. The beamline covers an energy range from 3.5 keV to 35.0 keV, which fulfills the requirements of the user community to perform anomalous scattering experiments. Mirrors are used to reduce the intensity of higher harmonics. Furthermore, the mirrors and 2D compound refracting lenses can focus the beam down to a few micrometres at the sample position. This option with the high photon flux enables also SAXS/WAXS tensor tomography experiments to be performed at this new beamline in a relatively short time. The first SAXS/ WAXS pattern was collected in August 2021, while the first user experiment was carried out two months later. Since January 2022 the beamline has been in regular user operation mode. In this paper the beamline optics and the SAXS/ WAXS instrument are described and two examples are briefly shown. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) are semiconductors with promising application in optoelectronic devices, particularly, in solar cell technologies. The chemical and electronic properties of MHPs at the surface and interfaces with adjacent layers dictate charge transfer within stacked devices and ultimately the efficiency of the latter. X‐ray photoelectron spectroscopy is a powerful tool to characterize these material properties. However, the X‐ray radiation itself can potentially affect the MHP and therefore jeopardize the reliability of the obtained information. In this work, the effect of X‐ray irradiation is assessed on Cs0.05MA0.15FA0.8Pb(I0.85Br0.15)3 (MA for CH3NH3, and FA for CH2(NH2)2) MHP thin‐film samples in a half‐cell device. There is a comparison of measurements acquired with synchrotron radiation and a conventional laboratory source for different times. Changes in composition and core levels binding energies are observed in both cases, indicating a modification of the chemical and electronic properties. The results suggest that changes observed over minutes with highly brilliant synchrotron radiation are likely occurring over hours when working with a lab‐based source providing a lower photon flux. The possible degradation pathways are discussed, supported by steady‐state photoluminescence analysis. The work stresses the importance of beam effect assessment at the beginning of XPS experiments of MHP samples. [ABSTRACT FROM AUTHOR]

The electrical‐substitution cryogenic detector BOLometer for Use in the range of X‐rays (BOLUX), which was developed some years ago at CEA/DAM, has been set up and restarted now at LNHB. It has been used for the primary measurement of the intensity (total energy per unit time) of monochromatic synchrotron beams in the energy range from 3 to 30 keV. These well‐determined photon beams have been employed for the efficiency calibration of two photodiodes in terms of current induced per unit optical power at different photon energies. In a final step, we explored the possibility to use these primary‐calibrated photodiodes to determine the efficiency curve of an energy‐dispersive spectrometer based on a semiconductor detector (Silicon Drift Detector) using less intense monochromatic photon fluxes. The characteristics of the radiometer BOLUX and its principle of operation are described, and the measurements carried out at the synchrotron beamline are presented, including the determination of the beams' intensities, the direct calibration of photodiodes with respect to BOLUX and the use of one of those photodiodes as a standard transfer for the calibration of the SDD. [ABSTRACT FROM AUTHOR]

Dose calculation plays a critical role in radiotherapy (RT) treatment planning, and there is a growing need to develop accurate dose deposition models that incorporate heterogeneous tumour properties. Deterministic models have demonstrated their capability in this regard, making them the focus of recent treatment planning studies as they serve as a basis for simplified models in RT treatment planning. In this study, we present a simplified deterministic model for photon transport based on the Boltzmann transport equation (BTE) as a proof‐of‐concept to illustrate the impact of heterogeneous tumour properties on RT treatment planning. We employ the finite element method (FEM) to simulate the photon flux and dose deposition in real cases of diffuse intrinsic pontine glioma (DIPG) and neuroblastoma (NB) tumours. Importantly, in light of the availability of pipelines capable of extracting tumour properties from magnetic resonance imaging (MRI) data, we highlight the significance of such data. Specifically, we utilise cellularity data extracted from DIPG and NB MRI images to demonstrate the importance of heterogeneity in dose calculation. Our model simplifies the process of simulating a RT treatment system and can serve as a useful starting point for further research. To simulate a full RT treatment system, one would need a comprehensive model that couples the transport of electrons and photons. [ABSTRACT FROM AUTHOR]

In our study, we aimed to show how different reaction parameters can affect production rates using photocatalytic hydrogen peroxide formation by different polymeric carbon nitrides (PCN). For this purpose, selected materials were first compared under the same reaction conditions and compared with TiO2 (P25). We also show that different light intensities can have a different influence on seemingly similar materials. Since hydrogen peroxide production in the presence of an electron donor proceeds mainly by reduction of oxygen, we also show an influence of the oxygen flow on the formation rates. Thus, with high oxygen fluxes and high intensities of irradiated light, we were able to achieve an H2O2 concentration of 125 mM after about 25 h. Finally, the two best PCN materials were selected to measure light intensity dependence at different wavelengths up to visible light. It was found that they behaved differently at the different wavelengths and thus it could be shown that an exact specification of the reaction parameters is indispensable for comparisons in the literature. [ABSTRACT FROM AUTHOR]

With a highly coherent, optically addressable electron spin, the nitrogen-vacancy (NV) center in diamond is a promising candidate for a node in a quantum network. A resonant microcavity can boost the flux of coherent photons emerging from single NV centers. Here, we present an open Fabry–Pérot microcavity geometry containing a single-crystal diamond membrane, which operates in a regime where the vacuum electric field is strongly confined to the diamond membrane. There is a field anti-node at the diamond–air interface. Despite the presence of surface losses, a finesse of F = 11 500 was observed. The quality (Q) factor for the lowest mode number is 120 000 ; the mode volume V is estimated to be 3.9 λ 0 3 , where λ 0 is the free-space wavelength. We investigate the interplay between different loss mechanisms and the impact these loss channels have on the performance of the cavity. This analysis suggests that the surface waviness (roughness with a spatial frequency comparable to that of the microcavity mode) is the mechanism preventing the Q / V ratio from reaching even higher values. Finally, we apply the extracted cavity parameters to the NV center and calculate a predicted Purcell factor exceeding 150. [ABSTRACT FROM AUTHOR]

The retina is a part of the brain that sits at the back of the eye, looking out onto the world. The first neurons of the retina are the rod and cone photoreceptors, which convert changes in photon flux into electrical signals that are the basis of vision. Rods and cones are frequent targets of heritable neurodegenerative diseases that cause visual impairment, including blindness, in millions of people worldwide. This review summarizes the diverse genetic causes of inherited retinal degenerations (IRDs) and their convergence onto common pathogenic mechanisms of vision loss. Currently, there are few effective treatments for IRDs, but recent advances in disparate areas of biology and technology (e.g., genome editing, viral engineering, 3D organoids, optogenetics, semiconductor arrays) discussed here enable promising efforts to preserve and restore vision in IRD patients with implications for neurodegeneration in less approachable brain areas. Kerschensteiner provides an overview of vision loss from inherited retinal degenerations, including its causes and the latest therapies being developed to treat it. [ABSTRACT FROM AUTHOR]