Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa2Cu3Oy.

Uniaxial pressure provides an efficient approach to control charge density waves in YBa2Cu3Oy. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials.

Contemporary outcomes of left thoraco-abdominal esophagectomy due to cancer in the esophagus or gastroesophageal junction, a multicenter cohort study.

Surgery for cancer of the esophagus or gastro-esophageal junction can be performed with a variety of minimally invasive and open approaches. The left thoracoabdominal esophagectomy (LTE) is an open technique that gives an opportunity to operate in the chest and abdomen with excellent exposure of the gastro-esophageal junction through a single incision, and there is currently no equivalent minimally invasive technique available. The aim of this multi-institutional review was to study a large contemporary international study cohort of patients treated with LTE. An international multicenter cohort study was performed including all patients treated with LTE at six high-volume centers for gastro-esophageal cancer surgery between 2012 and 2022. Patient data were prospectively collected in each participating centers' institutional database. Information about patient, tumor, and treatment details were collected. The study cohort included a total of 793 patients treated with LTE during the study period. The most frequently observed complications were pneumonia in 185/727 (25.5%) patients and atrial fibrillation in 91/727 (12.5%). Anastomotic leak occurred in 35/727 (4.8%) patients; no patient suffered from conduit necrosis. Thirty-day mortality occurred in 15/785 (1.9%) patients and 90-day mortality in 39/785 (5.0%) patients. Factors with statistically significant association with survival were American Society for Anesthesiologists-score, tumor location, tumor stage, and tumor free resection margins. Neoadjuvant therapy was not associated with increased survival compared to surgery alone but neoadjuvant chemoradiotherapy compared to neoadjuvant chemotherapy showed statistically significant improved survival with hazard ratio 0.60 (95% confidence intervals:0.44-0.80, P = 0.001) in a multivariable adjusted model. This study demonstrates that LTE can be applied in selected patients with results that are comparable to other large studies of open and minimally invasive surgery for esophageal or gastro-esophageal cancer at high-volume centers.

Mapping internal temperatures during high-rate battery applications.

Electric vehicles demand high charge and discharge rates creating potentially dangerous temperature rises. Lithium-ion cells are sealed during their manufacture, making internal temperatures challenging to probe1. Tracking current collector expansion using X-ray diffraction (XRD) permits non-destructive internal temperature measurements2; however, cylindrical cells are known to experience complex internal strain3,4. Here, we characterize the state of charge, mechanical strain and temperature within lithium-ion 18650 cells operated at high rates (above 3C) by means of two advanced synchrotron XRD methods: first, as entire cross-sectional temperature maps during open-circuit cooling and second, single-point temperatures during charge-discharge cycling. We observed that a 20-minute discharge on an energy-optimized cell (3.5 Ah) resulted in internal temperatures above 70 °C, whereas a faster 12-minute discharge on a power-optimized cell (1.5 Ah) resulted in substantially lower temperatures (below 50 °C). However, when comparing the two cells under the same electrical current, the peak temperatures were similar, for example, a 6 A discharge resulted in 40 °C peak temperatures for both cell types. We observe that the operando temperature rise is due to heat accumulation, strongly influenced by the charging protocol, for example, constant current and/or constant voltage; mechanisms that worsen with cycling because degradation increases the cell resistance. Design mitigations for temperature-related battery issues should now be explored using this new methodology to provide opportunities for improved thermal management during high-rate electric vehicle applications.

Acute appendicitis in elderly during Covid-19 pandemic.

PURPOSE: During the past months, the Italian Government has reduced the restrictions and access to hospitals. Since then, up to 40% of non-traumatic abdominal emergencies have had unusual delayed treatment. Given the rapidly evolving situation and the absence of evidence to support recommendations during the pandemic, it is useful to assess how the current situation is influencing the management of elderly with acute appendicitis. METHODS: Between February 2020 and December 2020, all patients older than 68 years old undergone appendectomy were included. Surgical approach, hospital stay, post-operative complications, radiology reports, and histologic examination were included in the retrospective analysis and compared with a same sample of the same period before the pandemic. RESULTS: Twenty-seven patients underwent appendectomy for acute appendicitis during the pandemic and 34 patients in the pre-outbreak period. Laparoscopic approach was completed in 51.8% of the cases, while conversion to laparotomy in 22.3% of patients and open procedure in the 25.9%, before the pandemic 73.6%, 14.7%, and 11.7%, respectively. During the pandemic, complicated appendicitis occurred in 59.3% of the cases (26.5% before the outbreak). One patient was treated for a pelvic abscess, while no minor complications were detected. No mortality rate was reported, with a mean hospital stay of 5.64 days during the outbreak and 4.21 days before the pandemic. CONCLUSION: Our data highlighted a partial delay in diagnosis in the elderly group, and an increase in complicated appendicitis also demonstrated by the need for conversion to laparotomy.

Exploring phase transitions and the emergence of structural complexity at the ESRF extremely brilliant source.

The underlying mechanisms of phase transitions and the emergence of complexity are long-standing fundamental subjects for which a complete and unified description is still missing. This is due to the intrinsic nature of condensed matter, which contains a very large number of interacting particles. The partial or complete resolution of these open questions will require a considerable development of the experimental and theoretical means. In this context, the newlydevelopedextremely brilliant x-ray source at the European Synchrotron Radiation Facility with its unprecedented performances will provide the scientific community with a unique tool to tackle such challenging objectives. In this review article, we will discuss, through some selected examples, the potential impact this new instrument could have in the short and long term in this field of research.

Melting Curve and Isostructural Solid Transition in Superionic Ice.

The phase diagram and melting curve of water ice is investigated up to 45 GPa and 1600 K by synchrotron x-ray diffraction in the resistively and laser heated diamond anvil cell. Our melting data evidence a triple point at 14.6 GPa, 850 K. The latter is shown to be related to a first-order solid transition from the dynamically disordered form of ice VII, denoted ice VII^{'}, toward a high-temperature phase with the same bcc oxygen lattice but larger volume and higher entropy. Our experiments are compared to ab initio molecular dynamics simulations, enabling us to identify the high-temperature bcc phase with the predicted superionic ice VII^{''} phase [J.-A. Hernandez and R. Caracas, Phys. Rev. Lett. 117, 135503 (2016).PRLTAO0031-900710.1103/PhysRevLett.117.135503].

Phase stability and electronic structure of iridium metal at the megabar range.

The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter. Synchrotron-based powder x-ray diffraction results highlight a large stability range (up to 1.4 Mbar) of the low-pressure phase. The compressibility behaviour was characterized by an accurate determination of the pressure-volume equation of state, with a bulk modulus of 339(3) GPa and its derivative of 5.3(1). X-ray absorption spectroscopy, which probes the local structure and the empty density of electronic states above the Fermi level, was also utilized. The remarkable agreement observed between experimental and calculated spectra validates the reliability of theoretical predictions of the pressure dependence of the electronic structure of iridium in the studied interval of compressions.

High-pressure polymorphism of BaFe2Se3.

BaFe2Se3 is a potential superconductor material exhibiting transition at 11 K and ambient pressure. Here we extended the structural and performed electrical resistivity measurements on this compound up to 51 GPa and 20 GPa, respectively, in order to distinguish if the superconductivity in this sample is intrinsic to the BaFe2Se3 phase or if it is originating from minor FeSe impurities that show a similar superconductive transition temperature. The electrical resistance measurements as a function of pressure show that at 5 GPa the superconducting transition is observed at around 10 K, similar to the one previously observed for this sample at ambient pressure. This indicates that the superconductivity in this sample is most likely intrinsic to the BaFe2Se3 phase and not to FeSe with T c > 20 K at these pressures. Further increase in pressure suppressed the superconductive signal and the sample remained in an insulating state up to the maximum achieved pressure of 20 GPa. Single-crystal and powder x-ray diffraction measurements revealed two structural transformations in BaFe2Se3: a second order transition above 3.5 GPa from Pnma (CsAg2I3-type structure) to Cmcm (CsCu2Cl3-type structure) and a first order transformation at 16.6 GPa. Here, γ-BaFe2Se3 transforms into δ-BaFe2Se3 (Cmcm, CsCu2Cl3-type average structure) via a first order phase transition mechanism. This transition is characterized by a significant shortening of the b lattice parameter of γ-BaFe2Se3 (17%) and accompanied by an anisotropic expansion in the orthogonal ac plane at the transition point.

Uniaxial pressure control of competing orders in a high-temperature superconductor.

Cuprates exhibit antiferromagnetic, charge density wave (CDW), and high-temperature superconducting ground states that can be tuned by means of doping and external magnetic fields. However, disorder generated by these tuning methods complicates the interpretation of such experiments. Here, we report a high-resolution inelastic x-ray scattering study of the high-temperature superconductor YBa2Cu3O6.67 under uniaxial stress, and we show that a three-dimensional long-range-ordered CDW state can be induced through pressure along the a axis, in the absence of magnetic fields. A pronounced softening of an optical phonon mode is associated with the CDW transition. The amplitude of the CDW is suppressed below the superconducting transition temperature, indicating competition with superconductivity. The results provide insights into the normal-state properties of cuprates and illustrate the potential of uniaxial-pressure control of competing orders in quantum materials.

Stability and nature of the volume collapse of ε-Fe2O3 under extreme conditions.

Iron oxides are among the major constituents of the deep Earth's interior. Among them, the epsilon phase of Fe2O3 is one of the less studied polymorphs and there is a lack of information about its structural, electronic and magnetic transformations at extreme conditions. Here we report the precise determination of its equation of state and a deep analysis of the evolution of the polyhedral units under compression, thanks to the agreement between our experiments and ab-initio simulations. Our results indicate that this material, with remarkable magnetic properties, is stable at pressures up to 27 GPa. Above 27 GPa, a volume collapse has been observed and ascribed to a change of the local environment of the tetrahedrally coordinated iron towards an octahedral coordination, finding evidence for a different iron oxide polymorph.

High-Pressure Synthesized Lithium Pentazolate Compound Metastable under Ambient Conditions.

Polynitrogen compounds have been actively pursued driven by their potential as ultra-high-performing propellants or explosives. Despite remarkable breakthroughs over the past two decades, the two figures of merit for a compelling material, namely a large fraction of nitrogen by weight and a bulk stability under ambient conditions, have not yet been achieved. We report the synthesis of a lithium pentazolate solid by compressing and laser-heating lithium embedded in molecular N2 around 45 GPa along with its recovery under ambient conditions. The observation by Raman spectroscopy of vibrational modes unique to the cyclo-N5- anion is the signature of the formation of LiN5. Mass spectroscopy experiments confirm the presence of the pentazolate anion in the recovered compound. A monoclinic lattice is obtained from X-ray diffraction measurements and the volume of the LiN5 compound under pressure is in good agreement with the theoretical calculations.

Topologically frustrated ionisation in a water-ammonia ice mixture.

Water and ammonia are considered major components of the interiors of the giant icy planets and their satellites, which has motivated their exploration under high P-T conditions. Exotic forms of these pure ices have been revealed at extreme (~megabar) pressures, notably symmetric, ionic, and superionic phases. Here we report on an extensive experimental and computational study of the high-pressure properties of the ammonia monohydrate compound forming from an equimolar mixture of water and ammonia. Our experiments demonstrate that relatively mild pressure conditions (7.4 GPa at 300 K) are sufficient to transform ammonia monohydrate from a prototypical hydrogen-bonded crystal into a form where the standard molecular forms of water and ammonia coexist with their ionic counterparts, hydroxide (OH-) and ammonium [Formula: see text] ions. Using ab initio atomistic simulations, we explain this surprising coexistence of neutral/charged species as resulting from a topological frustration between local homonuclear and long-ranged heteronuclear ionisation mechanisms.

Differential expression of synapsin genes during early zebrafish development.

Synapsins are a family of synaptic vesicle (SV)-associated phosphoproteins that have been identified in several vertebrates and invertebrates. We report here the cloning and expression of synapsin family genes in the zebrafish Danio rerio. We identified the complete coding sequence of synapsin 3, which is not present in the currently available genome, and characterized and annotated the synapsin gene family in the zebrafish D. rerio. By means of whole-mount in situ hybridization, we showed the spatiotemporal expression of synapsin genes at three different time points during early embryonic development: 20-24 h postfertilization (hpf), 30-33 hpf, and 3 days postfertilization (dpf). As very few data are available describing the expression of synapsin family genes during CNS development in vertebrate models, our results may help to achieve a better understanding of the complex functions of these molecules. Finally, new interesting evidence from our temporal gene expression studies suggests that synapsins have also maternal functions.

An x-ray scattering study of Sn2P2S6: absence of incommensurate phase up to 1 GPa.

The ferroelectric phase transition in a semiconductor Sn(2)P(2)S(6) single crystal has been studied by means of high-resolution synchrotron x-ray diffraction in the pressure-temperature range where an incommensurate modulated phase has been anticipated for many years. In contrast with the predictions, the present measurements reveal only a direct ferroelectric-paraelectric phase transition close to T = 100 K, p = 1.1 GPa. In the vicinity of this phase transition, a characteristic critical diffuse scattering was observed, but no satellite peaks could be resolved there. It is concluded that the earlier hypothesis about the presence of an incommensurate phase and associated Lifshitz point in the temperature-pressure phase diagram of Sn(2)P(2)S(6) is incorrect.

"Compressed graphite" formed during C60 to diamond transformation as revealed by scattering computed tomography.

The collapsing of C60 into polycrystalline diamond has been studied after nonhydrostatic pressurization at ambient temperature using x-ray scattering computed tomography. Using this selective structural probe we provide evidence of concentric coexistence of "compressed graphite" (d(00l)∼3.09-3.11 Å), sp2-graphitelike phase (d(00l)∼3.35-3.42 Å), and sp3-like amorphous carbon surrounding polycrystalline diamond (a∼3.56-3.59 Å). The so-called "compressed graphite" exhibits a collapsed c axis and is textured with disordered layers. This latter phase is better described as a short interlayered carbon phase with buckled sp2-sp3 layers with possible interlayer bonding. Additionally, our 3D maps of phase distribution and of the residual stress retained in the polycrystalline diamond phase support the importance of stressed synthesis conditions for diamond formation.

X-ray magnetic circular dichroism measurements in Ni up to 200 GPa: resistant ferromagnetism.

The structural stability of fcc Ni over a very large pressure range offers a unique opportunity to experimentally investigate how magnetism is modified by simple compression. K-edge x-ray magnetic circular dichroism (XMCD) shows that fcc Ni is ferromagnetic up to 200 GPa, contradicting recent predictions of an abrupt transition to a paramagnetic state at 160 GPa. Density functional theory calculations point out that the pressure evolution of the K-edge XMCD closely follows that of the p projected orbital moment rather than that of the total spin moment. The disappearance of magnetism in Ni is predicted to occur above 400 GPa.