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Chirality is a structural property of molecules lacking mirror symmetry that has strong implications in diverse fields, ranging from life sciences to materials science. Chirality-sensitive spectroscopic methods, such as circular dichroism, exhibit weak signal contributions on an achiral background. Helical dichroism, which is based on the orbital angular momentum (OAM) of light, offers a new approach to probe molecular chirality, but it has never been demonstrated on disordered samples. Furthermore, in the optical domain the challenge lies in the need to transfer the OAM of the photon to an electron that is localized on an ångström-size orbital. Here we overcome this challenge using hard X-rays with spiral Fresnel zone plates, which can induce an OAM. We present the helical dichroism spectra of a disordered powder sample of enantiopure salts of the molecular complex of [Fe(4,4′-diMebpy)3]2+ at the iron K edge (7.1 keV) with OAM-carrying beams. The asymmetry ratios for the helical dichroism spectra are within one to five percent for OAM beams with topological charges of one and three. These results open a new window into the studies of molecular chirality and its interaction with the OAM of light.Linearly polarized orbital angular momentum-carrying hard X-ray beams are induced using spiral Fresnel zone plates. By sending the hard X-ray beams to disordered enantiopure molecular complexes, the helicity-dependent and chiral-sensitive signal is obtained.

Coherent diffractive imaging is unique, being the only route for achieving high spatial resolution in the extreme ultraviolet and X-ray regions, limited only by the wavelength of the light. Recently, advances in coherent short-wavelength light sources, coupled with progress in algorithm development, have significantly enhanced the power of X-ray imaging. However, so far, high-fidelity diffraction imaging of periodic objects has been a challenge because the scattered light is concentrated in isolated peaks. Here, we use tabletop 13.5 nm high-harmonic beams to make two significant advances. First, we demonstrate high-quality imaging of an extended, nearly periodic sample for the first time. Second, we achieve subwavelength spatial resolution (12.6 nm) imaging at short wavelengths, also for the first time. The key to both advances is a novel technique called ‘modulus enforced probe’, which enables robust and quantitative reconstructions of periodic objects. This work is important for imaging next-generation nano-engineered devices. Coherent diffractive imaging of periodic samples is demonstrated with a tabletop, 13.5 nm high-harmonic source. With a novel image reconstruction technique, the record high spatial resolution of 12.6 nm is achieved in the extreme-ultraviolet region.

Optical-domain transient grating (TG) spectroscopy is a versatile background-free four-wave-mixing technique that is used to probe vibrational, magnetic and electronic degrees of freedom in the time domain1. The newly developed coherent X-ray free-electron laser sources allow its extension to the X-ray regime. X-rays offer multiple advantages for TG: their large penetration depth allows probing the bulk properties of materials, their element specificity can address core excited states, and their short wavelengths create excitation gratings with unprecedented momentum transfer and spatial resolution. Here, we demonstrate TG excitation in the hard X-ray range at 7.1 keV. In bismuth germanate (BGO), the non-resonant TG excitation generates coherent optical phonons detected as a function of time by diffraction of an optical probe pulse. This experiment demonstrates the ability to probe bulk properties of materials and paves the way for ultrafast coherent four-wave-mixing techniques using X-ray probes and involving nanoscale TG spatial periods.A four-wave mixing technique is developed in the hard X-ray range. A diamond phase grating in an X-ray beam path creates a periodic excitation pattern on a sample via the Talbot effect. The response of the periodic excitation is probed by an optical pulse.

The structure–function relationship is at the heart of biology, and major protein deformations are correlated to specific functions. For ferrous heme proteins, doming is associated with the respiratory function in hemoglobin and myoglobins. Cytochrome c (Cyt c) has evolved to become an important electron-transfer protein in humans. In its ferrous form, it undergoes ligand release and doming upon photoexcitation, but its ferric form does not release the distal ligand, while the return to the ground state has been attributed to thermal relaxation. Here, by combining femtosecond Fe Kα and Kβ X-ray emission spectroscopy (XES) with Fe K-edge X-ray absorption near-edge structure (XANES), we demonstrate that the photocycle of ferric Cyt c is entirely due to a cascade among excited spin states of the iron ion, causing the ferric heme to undergo doming, which we identify. We also argue that this pattern is common to a wide diversity of ferric heme proteins, raising the question of the biological relevance of doming in such proteins.

In haemoglobin the change from the low-spin (LS) hexacoordinated haem to the high spin (HS, S = 2) pentacoordinated domed deoxy-myoglobin (deoxyMb) form upon ligand detachment from the haem and the reverse process upon ligand binding are what ultimately drives the respiratory function. Here we probe them in the case of Myoglobin-NO (MbNO) using element- and spin-sensitive femtosecond Fe K α and K β X-ray emission spectroscopy at an X-ray free-electron laser (FEL). We find that the change from the LS (S = 1/2) MbNO to the HS haem occurs in ~800 fs, and that it proceeds via an intermediate (S = 1) spin state. We also show that upon NO recombination, the return to the planar MbNO ground state is an electronic relaxation from HS to LS taking place in ~30 ps. Thus, the entire ligand dissociation-recombination cycle in MbNO is a spin cross-over followed by a reverse spin cross-over process. The change from low-spin hexacoordinated to high-spin pentacoordinated domed form in heam upon ligand detachment and the reverse process underlie the respiratory function. The authors, using femtosecond time-resolved X-ray emission spectroscopy, capture the transient states connecting the two forms in myoglobin-NO upon NO photoinduced detachment.

Livestock buildings in rural areas are increasingly recognized for their environmental impact, yet few studies provide applied, scenario-based evaluations to guide retrofit interventions. While the existing literature acknowledges the environmental burden of livestock facilities, it often lacks operationally grounded analyses applicable to real-world agricultural contexts. This paper proposes an original integration of experimental climatic monitoring and life cycle assessment (LCA) to evaluate retrofit scenarios for energy efficiency in real poultry farming contexts. Based on an accurate climatic monitoring campaign conducted on-site during the spring and summer periods, relevant data were collected on air temperature, humidity, wind speed, and solar radiation affecting two poultry tunnels in central Italy, highlighting the need for thermal mitigation. The comparison between the observed operational scenario and the hypothesized improved scenario, involving energy supply from photovoltaic sources, evaluated using the PVGIS tool, demonstrated a significant reduction in environmental impact, with a 33.4% decrease in global warming potential and a 26.1% reduction in energy consumption. This study combines experimental on-site climatic data collection with comparative environmental evaluation using LCA methodology. The LCA approach, which guided the entire study, highlighted how the energy efficiency gained through solar panels adequately offsets their production and maintenance costs over the long term. These findings offer a replicable model for energy retrofits in rural livestock facilities, contributing to both environmental goals and rural resilience.

OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu–C and Cu–P bonds represents an underexplored type of luminophore. To investigate the charge transfer and structural rearrangements in this material, we apply complementary pump-probe X-ray techniques: absorption, emission, and scattering including pump-probe measurements at the X-ray free-electron laser SwissFEL. We find that the excitation leads to charge movement from C- and P- coordinated Cu sites and from the phosphorus atoms to phenyl rings; the Cu core slightly rearranges with 0.05 Å increase of the shortest Cu–Cu distance. The use of a Cu cluster bonded to the ligands through C and P atoms is an efficient way to keep structural rigidity of luminophores. Obtained data can be used to verify computational methods for the development of luminophores. OLED materials based on thermally activated delayed fluorescence have promising efficiency. Here, the authors investigate an organometallic multicore Cu complex as luminophore, by pump-probe X-ray techniques at three different facilities deriving a complete picture of the charge transfer in the triplet excited state.

To compare growth and glycemic control in children with type 1 diabetes and silent celiac disease treated with a gluten-free diet for 1 year with those of similar age and gender with type 1 diabetes but without celiac disease, 16 type 1 diabetes patients with silent celiac disease were enrolled and each celiac disease-positive case was matched for age, sex, and duration of diabetes with two type 1 diabetes controls with negative serologic markers of celiac disease. All 16 children with positive celiac disease serology had histologic features consistent with celiac disease despite the absence of symptoms. The mean growth and metabolic control values were similar between children with type 1 diabetes and celiac disease and those with type 1 diabetes but without celiac disease. This study seems to suggest that the early diagnosis of celiac disease and initiation of a gluten-free diet may prevent further deterioration in the nutritional status of children with type 1 diabetes and celiac disease and may reduce the prospect of celiac disease complications without any impact on type 1 diabetes control.

We present a new setup for resonant inelastic hard x-ray scattering at the Bernina beamline of SwissFEL with energy, momentum, and temporal resolution. The compact R = 0.5 m Johann-type spectrometer can be equipped with up to three crystal analyzers and allows efficient collection of RIXS spectra. Optical pumping for time-resolved studies can be realized with a broad span of optical wavelengths. We demonstrate the performance of the setup at an overall ∼180 meV resolution in a study of ground-state and photoexcited (at 400 nm) honeycomb 5d iridate α-Li2IrO3. Steady-state RIXS spectra at the iridium L3-edge (11.214 keV) have been collected and are in very good agreement with data collected at synchrotrons. The time-resolved RIXS transients exhibit changes in the energy loss region <2 eV, whose features mostly result from the hopping nature of 5d electrons in the honeycomb lattice. These changes are ascribed to modulations of the Ir-to-Ir inter-site transition scattering efficiency, which we associate to a transient screening of the on-site Coulomb interaction.

Background Mosquito-borne arboviral diseases represent a growing threat and serious worldwide concern for public health authorities. Host immunoglobulin G (IgG) responses to mosquito salivary antigens emerged as a useful additional tool to evaluate human–vector contact, which is crucial for transmission risk assessment and planning vector control interventions. We previously reported that IgG responses to the Aedes albopictus 34k2 salivary protein (al34k2) are suitable, although with some limitations, to reveal variation of human exposure to the tiger mosquito. In this study we evaluated the Ae. albopictus Ag5-3 (alAg5-3), an Antigen 5 family member specifically and abundantly expressed in the saliva of adult females. Methods IgG responses to recombinant alAg5-3, as well as to a combination of alAg5-3 and al34k2, were measured in a set of sera previously collected from healthy human blood donors before and after the summer season of exposure to mosquito bites. Surveys were conducted in two districts of Northeast Italy, Padua and Belluno, with different density and history of colonization by the tiger mosquito Ae. albopictus . Results A preliminary pilot study, performed on a small subset of individuals from Padua, indicated that alAg5-3 was more immunogenic than al34k2 and may be suitable to detect variations of exposure to Ae. albopictus . Analysis of the whole set of 523 sera showed that anti-alAg5-3 IgG levels significantly increased, in both study areas, after the summer period of high mosquito density. However, differences between the two study sites were only found when a mixture of the two antigens, alAg5-3 and al34k2, was used. Conclusions IgG responses to alAg5-3 represent a novel appropriate marker to evaluate seasonal variation of human exposure to Ae. albopictus and, because of its higher sensitivity, it appears preferable to al34k2, especially for longitudinal studies in conditions of low-to-moderate mosquito density. However, the combination of both antigens may be a better surrogate of Ae. albopictus saliva since it allows the detection of both temporal and spatial variations of exposure to Ae. albopictus bites. The high conservation of the Ag5-3 protein among Aedes species suggests it may be exploited to also reveal exposure to Aedes aegypti and perhaps to other Aedes species. Graphical Abstract