Geometric frustration of Jahn-Teller order in the infinite-layer lattice.

The Jahn-Teller effect, in which electronic configurations with energetically degenerate orbitals induce lattice distortions to lift this degeneracy, has a key role in many symmetry-lowering crystal deformations1. Lattices of Jahn-Teller ions can induce a cooperative distortion, as exemplified by LaMnO3 (refs. 2,3). Although many examples occur in octahedrally4 or tetrahedrally5 coordinated transition metal oxides due to their high orbital degeneracy, this effect has yet to be manifested for square-planar anion coordination, as found in infinite-layer copper6,7, nickel8,9, iron10,11 and manganese oxides12. Here we synthesize single-crystal CaCoO2 thin films by topotactic reduction of the brownmillerite CaCoO2.5 phase. We observe a markedly distorted infinite-layer structure, with ångström-scale displacements of the cations from their high-symmetry positions. This can be understood to originate from the Jahn-Teller degeneracy of the dxz and dyz orbitals in the d7 electronic configuration along with substantial ligand-transition metal mixing. A complex pattern of distortions arises in a [Formula: see text] tetragonal supercell, reflecting the competition between an ordered Jahn-Teller effect on the CoO2 sublattice and the geometric frustration of the associated displacements of the Ca sublattice, which are strongly coupled in the absence of apical oxygen. As a result of this competition, the CaCoO2 structure forms an extended two-in-two-out type of Co distortion following 'ice rules'13.

Linear-in-temperature resistivity for optimally superconducting (Nd,Sr)NiO2.

The occurrence of superconductivity in proximity to various strongly correlated phases of matter has drawn extensive focus on their normal state properties, to develop an understanding of the state from which superconductivity emerges1-4. The recent finding of superconductivity in layered nickelates raises similar interests5-8. However, transport measurements of doped infinite-layer nickelate thin films have been hampered by materials limitations of these metastable compounds: in particular, a high density of extended defects9-11. Here, by moving to a substrate (LaAlO3)0.3(Sr2TaAlO6)0.7 that better stabilizes the growth and reduction conditions, we can synthesize the doping series of Nd1-xSrxNiO2 essentially free from extended defects. In their absence, the normal state resistivity shows a low-temperature upturn in the underdoped regime, linear behaviour near optimal doping and quadratic temperature dependence for overdoping. This is phenomenologically similar to the copper oxides2,12 despite key distinctions-namely, the absence of an insulating parent compound5,6,9,10, multiband electronic structure13,14 and a Mott-Hubbard orbital alignment rather than the charge-transfer insulator of the copper oxides15,16. We further observe an enhancement of superconductivity, both in terms of transition temperature and range of doping. These results indicate a convergence in the electronic properties of both superconducting families as the scale of disorder in the nickelates is reduced.

Evidence for d-wave superconductivity of infinite-layer nickelates from low-energy electrodynamics.

The discovery of superconductivity in infinite-layer nickelates established another category of unconventional superconductors that shares structural and electronic similarities with cuprates. However, key issues of the superconducting pairing symmetry, gap amplitude and superconducting fluctuations are yet to be addressed. Here we utilize static and ultrafast terahertz spectroscopy to address these. We demonstrate that the equilibrium terahertz conductivity and non-equilibrium terahertz responses of an optimally Sr-doped nickelate film (superconducting transition temperature of Tc = 17 K) are in line with the electrodynamics of d-wave superconductivity in the dirty limit. The gap-to-Tc ratio (2Δ/kBTc) is found to be 3.4, indicating that the superconductivity falls in the weak coupling regime. In addition, we observed substantial superconducting fluctuations near Tc that do not extend into the deep normal state as the optimally hole-doped cuprates do. Our results support a d-wave system that closely resembles the electron-doped cuprates.

Superconductivity in an infinite-layer nickelate.

The discovery of unconventional superconductivity in (La,Ba)2CuO4 (ref. 1) has motivated the study of compounds with similar crystal and electronic structure, with the aim of finding additional superconductors and understanding the origins of copper oxide superconductivity. Isostructural examples include bulk superconducting Sr2RuO4 (ref. 2) and surface-electron-doped Sr2IrO4, which exhibits spectroscopic signatures consistent with a superconducting gap3,4, although a zero-resistance state has not yet been observed. This approach has also led to the theoretical investigation of nickelates5,6, as well as thin-film heterostructures designed to host superconductivity. One such structure is the LaAlO3/LaNiO3 superlattice7-9, which has been recently proposed for the creation of an artificially layered nickelate heterostructure with a singly occupied [Formula: see text] band. The absence of superconductivity observed in previous related experiments has been attributed, at least in part, to incomplete polarization of the eg orbitals10. Here we report the observation of superconductivity in an infinite-layer nickelate that is isostructural to infinite-layer copper oxides11-13. Using soft-chemistry topotactic reduction14-20, NdNiO2 and Nd0.8Sr0.2NiO2 single-crystal thin films are synthesized by reducing the perovskite precursor phase. Whereas NdNiO2 exhibits a resistive upturn at low temperature, measurements of the resistivity, critical current density and magnetic-field response of Nd0.8Sr0.2NiO2 indicate a superconducting transition temperature of about 9 to 15 kelvin. Because this compound is a member of a series of reduced layered nickelate crystal structures21-23, these results suggest the possibility of a family of nickelate superconductors analogous to copper oxides24 and pnictides25.

An archaeal transcription factor EnfR with a novel 'eighth note' fold controls hydrogen production of a hyperthermophilic archaeon Thermococcus onnurineus NA1.

Thermococcus onnurineus NA1, a hyperthermophilic carboxydotrophic archaeon, produces H2 through CO oxidation catalyzed by proteins encoded in a carbon monoxide dehydrogenase (CODH) gene cluster. TON_1525 with a DNA-binding helix-turn-helix (HTH) motif is a putative repressor regulating the transcriptional expression of the codh gene cluster. The T55I mutation in TON_1525 led to enhanced H2 production accompanied by the increased expression of genes in the codh cluster. Here, TON_1525 was demonstrated to be a dimer. Monomeric TON_1525 adopts a novel 'eighth note' symbol-like fold (referred to as 'eighth note' fold regulator, EnfR), and the dimerization mode of EnfR is unique in that it has no resemblance to structures in the Protein Data Bank. According to footprinting and gel shift assays, dimeric EnfR binds to a 36-bp pseudo-palindromic inverted repeat in the promoter region of the codh gene cluster, which is supported by an in silico EnfR/DNA complex model and mutational studies revealing the implication of N-terminal loops as well as HTH motifs in DNA recognition. The DNA-binding affinity of the T55I mutant was lowered by ∼15-fold, for which the conformational change of N-terminal loops is responsible. In addition, transcriptome analysis suggested that EnfR could regulate diverse metabolic processes besides H2 production.

Resolving the polar interface of infinite-layer nickelate thin films.

Nickel-based superconductors provide a long-awaited experimental platform to explore possible cuprate-like superconductivity. Despite similar crystal structure and d electron filling, however, superconductivity in nickelates has thus far only been stabilized in thin-film geometry, raising questions about the polar interface between substrate and thin film. Here we conduct a detailed experimental and theoretical study of the prototypical interface between Nd1-xSrxNiO2 and SrTiO3. Atomic-resolution electron energy loss spectroscopy in the scanning transmission electron microscope reveals the formation of a single intermediate Nd(Ti,Ni)O3 layer. Density functional theory calculations with a Hubbard U term show how the observed structure alleviates the polar discontinuity. We explore the effects of oxygen occupancy, hole doping and cation structure to disentangle the contributions of each for reducing interface charge density. Resolving the non-trivial interface structure will be instructive for future synthesis of nickelate films on other substrates and in vertical heterostructures.

Long-term prognostic factors for cardiovascular events in patients with chest pain without diabetes mellitus nor significant coronary stenosis.

Chest pain is the most common symptom of coronary artery disease (CAD) and diabetes mellitus (DM) is a well-known single strongest risk factor for cardiovascular diseases. Thus, the impact of CAD nor DM on long-term clinical effects is reported widely, but the prognostic factors of non-DM patients presenting with chest pain without significant CAD are limited. A total of 1,046 patients with chest pain without DM and significant CAD who underwent coronary angiography (CAG) and acetylcholine (ACH) provocation tests were finally enrolled. Propensity score matching and multivariate Cox-proportional hazard ratio analysis were performed to adjust for baseline potential confounders. Major adverse cardiac and cerebrovascular events (MACCE) were defined as the composite of total death, myocardial infarction (MI), revascularization, stroke, and recurrent angina. This study aimed to evaluate the long-term prognostic factors for MACCE in patients with chest pain without DM and CAD up to 5 years. Coronary artery spasm (CAS) was the most common cause of chest pain. However, long-term MACCE of CAS was not worse than those of patients with chest pain without CAS when patients with CAS had subsequent optimal antianginal medication therapy. However, a recurrent chest pain remains a problem even with continuous antianginal medication therapy. Up to 5 years, the incidence of MACCE was in 7.3%, including recurrent angina 6.9%. Dyslipidemia (HR: 2.010, 95% CI 1.166-3.466, P = 0.012), mild-moderate (30-70%) coronary stenosis (HR: 2.369, 95% CI 1.118-5.018, P = 0.024), the use of aspirin (HR: 2.885, 95% CI 1.588-5.238, P < 0.001), and the use of nitrates (HR: 1.938, 95% CI 1.094-3.433, P = 0.023) were independent risk factors for MACCE. Among the patients with chest pain without DM and significant CAD, the incidence of MACE were rare, but recurrent angina was still a challenging problem who had treated with antianginal medications.

Doping evolution of the Mott-Hubbard landscape in infinite-layer nickelates.

The recent observation of superconductivity in [Formula: see text] has raised fundamental questions about the hierarchy of the underlying electronic structure. Calculations suggest that this system falls in the Mott-Hubbard regime, rather than the charge-transfer configuration of other nickel oxides and the superconducting cuprates. Here, we use state-of-the-art, locally resolved electron energy-loss spectroscopy to directly probe the Mott-Hubbard character of [Formula: see text] Upon doping, we observe emergent hybridization reminiscent of the Zhang-Rice singlet via the oxygen-projected states, modification of the Nd 5d states, and the systematic evolution of Ni 3d hybridization and filling. These experimental data provide direct evidence for the multiband electronic structure of the superconducting infinite-layer nickelates, particularly via the effects of hole doping on not only the oxygen but also nickel and rare-earth bands.

Gate Controlled Excitonic Emission in Quantum Dot Thin Films.

Formation of charged trions is detrimental to the luminescence quantum efficiency of colloidal quantum dot (QD) thin films as they predominantly undergo nonradiative recombination. In this regard, control of charged trion formation is of interest for both fundamental characterization of the quasi-particles and performance optimization. Using CdSe/CdS QDs as a prototypical material system, here we demonstrate a metal-oxide-semiconductor capacitor based on QD thin films for studying the background charge effect on the luminescence efficiency and lifetime. The concentration ratio of the charged and neutral quasiparticles in the QDs is reversibly controlled by applying a gate voltage, while simultaneous steady-state and time-resolved photoluminescence measurements are performed. Notably, the photoluminescence intensity is modulated by up to 2 orders of magnitude with a corresponding change in the effective lifetime. In addition, chip-scale modulation of brightness is demonstrated, where the photoluminescence is effectively turned on and off by the gate, highlighting potential applications in voltage-controlled electrochromics.

Korean vs. Western Exercise Capacity Nomograms for Korean Patients With Cardiovascular Disease.

BACKGROUND: Exercise capacity is known to be an independent predictor of cardiovascular events and mortality. However, most previous studies were based on Western populations. Further study is warranted for Asian patients according to ethnic or national standards. We aimed to compare prognostic values of Korean and Western nomograms for exercise capacity in Korean patients with cardiovascular disease (CVD). METHODS: In this retrospective cohort study, we enrolled 1,178 patients (62 ± 11 years; 78% male) between June 2015 and May 2020, who were referred for cardiopulmonary exercise testing in our cardiac rehabilitation program. The median follow-up period was 1.6 years. Exercise capacity was measured in metabolic equivalents by direct gas exchange method during the treadmill test. The nomogram for exercise capacity from healthy Korean individuals and a previous landmark Western study was used to determine the percentage of predicted exercise capacity. The primary endpoint was the composite of major adverse cardiovascular events (MACE; all-cause death, myocardial infarction, repeat revascularization, stroke and hospitalization for heart failure). RESULTS: A multivariate analysis showed that the risk of primary endpoint was more than double (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.10-4.40) in the patients with lower exercise capacity (< 85% of predicted) by Korean nomogram. The lower exercise capacity was one of the strong independent predictors along with left ventricular ejection fraction, age, and level of hemoglobin. However, the lower exercise capacity by Western nomogram could not predict the primary endpoint (HR, 1.33; 95% CI, 0.85-2.10). CONCLUSION: Korean patients with CVD with lower exercise capacity have higher risk of MACE. Considering inter-ethnic differences in cardiorespiratory fitness, the Korean nomogram provides more suitable reference values than the Western nomogram to determine lower exercise capacity and predict cardiovascular events in Korean patients with CVD.

Effect of permissive hypercarbia on lung oxygenation during one-lung ventilation and postoperative pulmonary complications in patients undergoing thoracic surgery: A prospective randomised controlled trial.

BACKGROUND: The effect of hypercarbia on lung oxygenation during thoracic surgery remains unclear. OBJECTIVE: To investigate the effect of hypercarbia on lung oxygenation during one-lung ventilation in patients undergoing thoracic surgery and evaluate the incidence of postoperative pulmonary complications. DESIGN: Prospective randomised controlled trial. SETTING: A tertiary university hospital in the Republic of Korea from November 2019 to December 2020. PATIENTS: Two hundred and ninety-seven patients with American Society of Anaesthesiologists physical status II to III, scheduled to undergo elective lung resection surgery. INTERVENTION: Patients were randomly assigned to Group 40, 50, or 60. An autoflow ventilation mode with a lung protective ventilation strategy was applied to all patients. Respiratory rate was adjusted to maintain a partial pressure of arterial carbon dioxide of 40 ±â€Š5 mmHg in Group 40, 50 ±â€Š5 mmHg in Group 50 and 60 ±â€Š5 mmHg in Group 60 during one-lung ventilation and at the end of surgery. MAIN OUTCOME MEASURES: The primary outcome was the arterial oxygen partial pressure/fractional inspired oxygen ratio after 60 min of one-lung ventilation. RESULTS: Data from 262 patients were analysed. The partial pressure/fractional inspired oxygen ratio was significantly higher in Group 50 and Group 60 than in Group 40 (269.4 vs. 262.9 vs. 214.4; P  < 0.001) but was not significantly different between Group 50 and Group 60. The incidence of postoperative pulmonary complications was comparable among the three groups. CONCLUSION: Permissive hypercarbia improved lung oxygenation during one-lung ventilation without increasing the risk of postoperative pulmonary complications or the length of hospital stay. TRIAL REGISTRATION: NCT04175379.

Development of Path Generation and Algorithm for Autonomous Combine Harvester Using Dual GPS Antenna.

Research on autonomous driving technology is actively underway to solve the facing problems in the agricultural field. Combine harvesters used in East Asian countries, including Korea, are tracked-type vehicles. The steering control system of the tracked vehicle has different characteristics from the wheeled vehicle used in the agricultural tractor. In this paper, a dual GPS antenna-based autonomous driving system and path tracking algorithm were developed for a robot combine harvester. An α-turn-type work path generation algorithm and a path tracking algorithm were developed. The developed system and algorithm were verified through experiments using actual combine harvesters. The experiment consisted of an experiment with harvesting work and an experiment without harvesting work. In the experiment without harvesting work, an error of 0.052 m occurred during working driving and 0.207 m during turning driving. In the experiment where the harvesting work was carried out, an error of 0.038 m occurred during work driving and 0.195 m during turning driving. As a result of comparing the non-work area and driving time to the results of manual driving, the self-driving experiment with harvesting work showed an efficiency of 76.7%.

Transcription activation of two clusters for exopolysaccharide biosynthesis by phosphorylated DctD in Vibrio vulnificus.

NtrC-mediated production of exopolysaccharides (EPS), essential components for Vibrio vulnificus biofilms, is highly increased in the presence of dicarboxylic or tricarboxylic acids. Gel-shift assays showed that regulation of the EPS-gene cluster I (EPS-I cluster) by NtrC was direct via binding of phosphorylated NtrC (p-NtrC) to the regulatory region of the EPS-I cluster. In contrast, p-NtrC did not bind to the EPS-II and EPS-III clusters, suggesting that NtrC regulation was not direct and another transcription factor belonging to an NtrC-regulon might play a role in activating their transcription. A candidate transcription factor, DctD, of which expression was induced by NtrC, activated the expression of the EPS-II and EPS-III clusters via direct binding to their upstream regions. Under growth conditions with either dicarboxylic or tricarboxylic acids, the expression of NtrC was induced and the transcription of dctD was activated. Furthermore, DctD exhibited higher transcriptional activity under the conditions with dicarboxylic acids than with tricarboxylic acids. Therefore, this study demonstrates that under dicarboxylate-rich conditions, both the abundance and activity of DctD were markedly induced, which activates the expression of two EPS clusters to maximize biosynthesis of EPS facilitating biofilm maturation in V. vulnificus.

Cooperative insertion of CO2 in diamine-appended metal-organic frameworks.

The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as 'phase-change' adsorbents, with unusual step-shaped CO2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO2 from various gas mixtures, and yield insights into the conservation of Mg(2+) within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes.

A Superconducting Praseodymium Nickelate with Infinite Layer Structure.

A variety of nickel oxide compounds have long been studied for their manifestation of various correlated electron phenomena. Recently, superconductivity was observed in nanoscale infinite layer nickelate thin films of Nd0.8Sr0.2NiO2, epitaxially stabilized on SrTiO3 substrates via topotactic reduction from the perovskite precursor phase. Here, we present the synthesis and properties of PrNiO2 thin films on SrTiO3. Upon doping in Pr0.8Sr0.2NiO2, we observe superconductivity with a transition temperature of 7-12 K and robust critical current density at 2 K of 334 kA/cm2. These findings indicate that superconductivity in the infinite layer nickelates is relatively insensitive to the details of the rare earth 4f configuration. Furthermore, they motivate the exploration of a broader family of compounds based on two-dimensional NiO2 planes, which will enable systematic investigation of the superconducting and normal state properties and their underlying mechanisms.

Aging in Place With a Spouse in Need: Neighborhood Cohesion and Older Adult Spouses' Physical and Mental Health.

This study examines the association of perceived neighborhood cohesion (NC) with older adults' health and the buffering effects of NC against the negative effects of spousal caregiving on health. Data of 3329 community-living older adults living with a spouse in need of care from the Health and Retirement Study were collected at two time-points. Multiple regression analyses were computed for each of the four health outcomes. For men, NC predicted fewer depressive symptoms and better cognition. NC buffered the negative effect of providing activities of daily living (ADL) help to the wife on cognition. For women, NC predicted fewer depressive symptoms and better cognition. NC buffered the negative effect of providing ADL help to the husband on ADL difficulties. The results accentuate the importance of residency location for older adults' physical and mental health. The health benefits of NC may have more implications for older adults providing spousal care.

Polar landmark protein HubP recruits flagella assembly protein FapA under glucose limitation in Vibrio vulnificus.

How motile bacteria recognize their environment and decide whether to stay or navigate toward more favorable location is a fundamental issue in survival. The flagellum is an elaborate molecular device responsible for bacterial locomotion, and the flagellum-driven motility allows bacteria to move themselves to the appropriate location at the right time. Here, we identify the polar landmark protein HubP as a modulator of polar flagellation that recruits the flagellar assembly protein FapA to the old cell pole, thereby controlling its activity for the early events of flagellar assembly in Vibrio vulnificus. We show that dephosphorylated EIIAGlc of the PEP-dependent sugar transporting phosphotransferase system sequesters FapA from HubP in response to glucose and hence inhibits FapA-mediated flagellation. Thus, flagellar assembly and motility is governed by spatiotemporal control of FapA, which is orchestrated by the competition between dephosphorylated EIIAGlc and HubP, in the human pathogen V. vulnificus.

Superconducting Dome in Nd_{1-x}Sr_{x}NiO_{2} Infinite Layer Films.

We report the phase diagram of Nd_{1-x}Sr_{x}NiO_{2} infinite layer thin films grown on SrTiO_{3}. A superconducting dome spanning 0.125