Atomic scale studies of La/Sr ordering in colossal magnetoresistant La(2-2x)Sr(1+2x)Mn2O7 single crystals.

To date, it is unclear whether chemical order (or disorder) is in any way connected to double exchange, electronic phase separation, or charge ordering (CO) in manganites. In this work, we carry out an atomic resolution study of the colossal magnetoresistant manganite La(2-2x)Sr(1+2x)Mn2O7 (LSMO). We combine aberration-corrected electron microscopy and spectroscopy with spectroscopic image simulations, to analyze cation ordering at the atomic scale in real space in a number of LSMO single crystals. We compare three different compositions within the phase diagram: a ferromagnetic metallic material (x=0.36), an insulating, antiferromagnetic charge ordered (AF-CO) compound (x=0.5), which also exhibits orbital ordering, and an additional AF sample (x=0.56). Detailed image simulations are essential to accurately quantify the degree of chemical ordering of these samples. We find a significant degree of long-range chemical ordering in all cases, which increases in the AF-CO range. However, the degree of ordering is never complete nor can it explain the strongly correlated underlying ordering phenomena. Our results show that chemical ordering over distinct crystallographic sites is not needed for electronic ordering phenomena to appear in manganites, and cannot by itself explain the complex electronic behavior of LSMO.

Clinical characteristics of primary aldosteronism screened from Chinese patients with hypertension: The China primary aldosteronism prospective study.

We investigated the clinical characteristics of primary aldosteronism (PA) screened from patients with hypertension in China. The participants were hypertensive patients who were suspected of PA and registered in the China Primary Aldosteronism Prospective Study. Plasma aldosterone-to-renin ratio (ARR) was used as the screening test. In patients screened positive for PA, that is, an ARR exceeding the thresholds and plasma aldosterone concentration (PAC) > 100 pg/mL, a confirmatory test was performed for diagnosis. Patients with PA underwent a CT scan and adrenal venous sampling for subtyping. Of the 1497 screened patients, 754 (50.4%) had an ARR exceeding the diagnostic threshold and 637 (84.5% of those eligible) were registered. These registered hypertensive patients with suspected PA had a mean (standard deviation) age of 52.6 ± 12.1 years, and included 442 (58.6%) women. In multiple stepwise logistic regression, the significant odds ratios for the presence of diagnosed (n = 490) versus suspected and non-diagnosed PA (n = 147) were 4.54 (95% CI: 2.78-7.39) for a history of hypokalemia, 0.79 (95% CI: 0.64-0.98) for a 0.9 mmol/l higher serum total cholesterol, and 2.25 (95% CI: 1.63-3.10) for a doubling of PAC in the supine or standing/sitting position. In multiple stepwise logistic regression, the significant odds ratios for the presence of unilateral (n = 135) versus bilateral PA (n = 53) were 3.04 (95% CI: 1.90-4.87) for a 0.4 mmol/l lower minimum serum potassium concentration and 1.86 (95% CI: 1.20-2.86) for a 0.3 mmol/l higher serum high-density lipoprotein cholesterol. PA might be a biochemical continuum in the adrenal hypersecretion of aldosterone as well as hypokalemia.

Chiral phase transition in charge ordered 1T-TiSe2.

It was recently discovered that the low-temperature, charge-ordered phase of 1T-TiSe(2) has a chiral character. This unexpected chirality in a system described by a scalar order parameter could be explained in a model where the emergence of relative phase shifts between three charge density wave components breaks the inversion symmetry of the lattice. Here, we present experimental evidence for the sequence of phase transitions predicted by that theory, going from disorder to nonchiral and finally to chiral charge order. Employing x-ray diffraction, specific heat, and electrical transport measurements, we find that a novel phase transition occurs ~7 K below the main charge ordering transition in TiSe(2), in agreement with the predicted hierarchy of charge-ordered phases.

A new machine learning-based prediction model for subtype diagnosis in primary aldosteronism.

Introduction: Unilateral primary aldosteronism (UPA) and bilateral primary aldosteronism (BPA) are the two subtypes of PA. Discriminating UPA from BPA is of great significance. Although adrenal venous sampling (AVS) is the gold standard for diagnosis, it has shortcomings. Thus, improved methods are needed. Methods: The original data were extracted from the public database "Dryad". Ten parameters were included to develop prediction models for PA subtype diagnosis using machine learning technology. Moreover, the optimal model was chose and validated in an external dataset. Results: In the modeling dataset, 165 patients (71 UPA, 94 BPA) were included, while in the external dataset, 43 consecutive patients (20 UPA, 23 BPA) were included. The ten parameters utilized in the prediction model include age, sex, systolic and diastolic blood pressure, aldosterone to renin ratio (ARR), serum potassium, ARR after 50 mg captopril challenge test (CCT), primary aldosterone concentration (PAC) after saline infusion test (SIT), PAC reduction rate after SIT, and number of types of antihypertensive agents at diagnosis. The accuracy, sensitivity, specificity, F1 score, and AUC for the optimal model using the random forest classifier were 90.0%, 81.8%, 96.4%, 0.878, and 0.938, respectively, in the testing dataset and 81.4%, 90.0%, 73.9%, 0.818 and 0.887, respectively, in the validating external dataset. The most important variables contributing to the prediction model were PAC after SIT, ARR, and ARR after CCT. Discussion: We developed a machine learning-based predictive model for PA subtype diagnosis based on ten clinical parameters without CT imaging. In the future, artificial intelligence-based prediction models might become a robust prediction tool for PA subtype diagnosis, thereby, might reducing at least some of the requests for CT or AVS and assisting clinical decision-making.

Yb3AuGe2In3: an ordered variant of the YbAuIn structure exhibiting mixed-valent Yb behavior.

Yb(3)AuGe(2)In(3) was obtained as large single crystals in high yield from reactions run in liquid indium. Single crystal X-ray diffraction data show that Yb(3)AuGe(2)In(3) is an ordered variant of YbAuIn with lattice constants, a = b = 7.3153(8) Å and c = 4.4210(5) Å, and space group P(6)2m. The parent compound YbAuIn was also studied for comparison. YbAuIn crystallizes in the ZrNiAl structure type, hexagonal, P(6)2m space group with lattice parameters a = b = 7.7127(11) Å and c = 4.0294(8) Å. In Yb(3)AuGe(2)In(3), Ge substitutes for one of the two Au positions in the ternary compound Yb(3)Au(3)In(3). The structure can be described as alternating [Ge(2)In(3)] and [Yb(3)Au] slabs that stack along the c-axis. The magnetic susceptibility data follow a modified Curie-Weiss law. The effective magnetic moment µ(eff) of 0.52 µ(B)/Yb atom was deduced from the Curie constant and Curie-Weiss constant of θ(p) = -1.5 K indicating antiferromagnetic interactions in Yb(3)AuGe(2)In(3). X-ray absorption near edge spectroscopy (XANES) measurements indicate intermediate valency for Yb in both compounds. The metallic nature of both compounds was confirmed by the resistivity measurements. Specific heat data for Yb(3)AuGe(2)In(3) and YbAuIn give an electronic γ term of 31 and 84 mJ/mol·K(2), respectively, suggesting that the ternary analog is a "light" heavy fermion compound.

Experimental investigation of flow over two-dimensional multiple hill models.

The aim of this study is to investigate the flow field characteristics in ABL (Atmospheric Boundary Layer) flow over multiple hills and valleys in two-dimensional models under neutral conditions. Active turbulence grids and boundary layer generation frame were used to simulate the natural winds in wind tunnel experiments. As a result, the mean wind velocity, the velocity vector diagram and turbulence intensity around the hills were investigated by using a PIV (Particle Image Velocimetry) system. From the measurement results, it was known that the average velocity was increased along the upstream slope of upside hill, and then separated at the top of the hills, the acceleration region of U/Uref>1 was generated at the downstream of the hill. Meanwhile, a large clockwise circulation flow was generated between the two hill models. Moreover, the turbulence intensity showed small value in the circulation flow regions. Compared to 1H model, the turbulence intensity in the mainstream direction showed larger value than that in the vertical direction. This paper provided a better understanding of the wind energy distribution on the terrain for proper selection of suitable sites for installing wind farms in the ABL.

Evidence of photo-induced dynamic competition of metallic and insulating phase in a layered manganite.

We show evidence that the competition between the antiferromagetic metallic phase and the charge- and orbital-ordered insulating phase at the reentrant phase boundary of a layered manganite, La0.99Sr2.01Mn2O7, can be manipulated using ultrafast optical excitation. The time-dependent evolution of the Jahn-Teller superlattice reflection, which indicates the formation of the charge and orbital order, was measured at different laser fluences. The laser-induced enhancement and reduction the Jahn-Teller reflection intensity shows a reversal of sign between earlier (~10 ns) and later (~150 ns) time delays during the relaxation after photo excitation. This effect is consistent with a scenario whereby the laser excitation modulates the local competition between the metallic and the insulating phases.

Reentrant orbital order and the true ground state of LaSr2Mn2O7.

Contrary to conventional wisdom, our purified La 2-2x Sr 1+2x Mn2O7 crystals exhibit CE-type orbital and charge order as the low-temperature ground state for a hole doping level h=0.5. For small deviations from h=0.5, the high-temperature CE phase is replaced at low temperatures by an A-type antiferromagnet without coexistence. Larger deviations result in a lack of CE order at any temperature. Thus, small inhomogeneities in cation or oxygen composition could explain why others commonly see this reentrance with coexistence.

First-order metal-insulator transitions in manganites: are they universal?

Conductivity data for La(2-2x)Sr(1+2xMn2O7 (x = 0.6) show a first-order transition from an orbital- or charge-ordered insulator to a metal as the temperature falls below approximately 160 K. The change in conductivity is 100 times larger than that seen previously in any single-phase manganite in zero field. The metallic low-temperature state is similar to x = 0.58, but x = 0.58 shows no evidence of orbital or charge order. This result supports a conclusion that strongly coupled magnetic-conductive transitions are first order.