Colossal magnetoresistance in EuZn2_2P2_2 and its electronic and magnetic structure

We investigate single crystals of the trigonal antiferromagnet EuZn$_2$P$_2$ ($P\overline{3}m1$) by means of electrical transport, magnetization measurements, X-ray magnetic scattering, optical reflectivity, angle-resolved photoemission spectroscopy (ARPES) and ab-initio band structure calculations (DFT+U). We find that the electrical resistivity of EuZn$_2$P$_2$ increases strongly upon cooling and can be suppressed in magnetic fields by several orders of magnitude (CMR effect). Resonant magnetic scattering reveals a magnetic ordering vector of $q = (0\, 0\, \frac{1}{2})$, corresponding to an $A$-type antiferromagnetic (AFM) order, below $T_{\rm N} = 23.7\,\rm K$. We find that the moments are canted out of the $a-a$ plane by an angle of about $40^{\circ}\pm 10^{\circ}$ degrees and tilted away from the [100] - direction by $30^{\circ}\pm 5^{\circ}$. We observe nearly isotropic magnetization behavior for low fields and low temperatures which is consistent with the magnetic scattering results. The magnetization measurements show a deviation from the Curie-Weiss behavior below $\approx 150\,\rm K$, the temperature below which also the field dependence of the material's resistivity starts to increase. An analysis of the infrared reflectivity spectrum at $T=295\,\rm K$ allows us to resolve the main phonon bands and intra-/interband transitions, and estimate indirect and direct band gaps of $E_i^{\mathrm{opt}}=0.09\,\rm{eV}$ and $E_d^{\mathrm{opt}}=0.33\,\rm{eV}$, respectively, which are in good agreement with the theoretically predicted ones. The experimental band structure obtained by ARPES is nearly $T$-independent above and below $T_{\rm N}$. The comparison of the theoretical and experimental data shows a weak intermixing of the Eu 4$f$ states close to the $\Gamma$ point with the bands formed by the phosphorous 3$p$ orbitals leading to an induction of a small magnetic moment at the P sites

Site- and spin-dependent coupling at the highly ordered h-BN/Co(0001) interface

Using photoelectron diffraction and spectroscopy, we explore the structural and electronic properties of the hexagonal boron nitride (h-BN) monolayer epitaxially grown on the Co(0001) surface. Perfect matching of the lattice parameters allows formation of a well-defined interface where the B atoms occupy the hollow sites while the N atoms are located above the Co atoms. The corrugation of the h-BN monolayer and its distance from the substrate were determined by means of R-factor analysis. The obtained results are in perfect agreement with the density functional theory (DFT) predictions. The electronic structure of the interface is characterized by a significant mixing of the h-BN and Co states. Such hybridized states appear in the h-BN band gap. This allows to obtain atomically resolved scanning tunneling microscopy (STM) images from the formally insulating 2D material being in contact with ferromagnetic metal. The STM images reveal mainly the nitrogen sublattice due to a dominating contribution of nitrogen orbitals to the electronic states at the Fermi level. We believe that the high quality, well-defined structure and interesting electronic properties make the h-BN/Co(0001) interface suitable for spintronic applications.L.V.Ya. acknowledges the RSF (Grant No. 16-42-01093). A.V.T., V.O.S., K.A.B., O.Yu.V., and D.Yu.U. acknowledge St. Petersburg State University for research Grant No. 11.65.42.2017. M.V.K. and I.I.O. acknowledge the RFBR (Grant No. 16-29-06410). C.L. acknowledges the DFG (Grant Nos. LA655-17/1 and LA655-19/1).Peer reviewe

The genetics of blood pressure regulation and its target organs from association studies in 342,415 individuals

To dissect the genetic architecture of blood pressure and assess effects on target-organ damage, we analyzed 128,272 SNPs from targeted and genome-wide arrays in 201,529 individuals of European ancestry and genotypes from an additional 140,886 individuals were used for validation. We identified 66 blood pressure loci, of which 17 were novel and 15 harbored multiple distinct association signals. The 66 index SNPs were enriched for cis-regulatory elements, particularly in vascular endothelial cells, consistent with a primary role in blood pressure control through modulation of vascular tone across multiple tissues. The 66 index SNPs combined in a risk score showed comparable effects in 64,421 individuals of non-European descent. The 66-SNP blood pressure risk score was significantly associated with target-organ damage in multiple tissues, with minor effects in the kidney. Our findings expand current knowledge of blood pressure pathways and highlight tissues beyond the classic renal system in blood pressure regulation

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Dependence of the Registered Blood Flow in Incoherent Optical Fluctuation Flowmetry on the Mean Photon Path Length in a Tissue

Laser-based medical techniques for evaluating blood flow (BF), such as laser Doppler flowmetry, laser speckle contrast imaging, etc., are known, but expensive and have some disadvantages. Recently, we have proposed a new technique—incoherent optical fluctuation flowmetry (IOFF), which is realized using a LED-based optical probe. This work aims to theoretically study the dependence of BF registered by IOFF on the source-detector distance (SDD) in the probe. For this purpose, we developed a three-layer optical model of skin and used Monte Carlo (MC) simulations of light propagation. All computations were performed for a wavelength of 810 nm and several SDDs from 1 to 14 mm. MC results showed that the BF depends nonlinearly on the SDD. Herewith, the BF is strongly correlated with the mean photon path length in a tissue (R = 0.92). Thus, flowmeters with different SDDs can give different BF values on the same patient. Based on the study results, to standardize BF measurements, it has been justified that BF magnitudes measured should be normalized to the exponential function of the SDD in the used optical probe in the form of [1 − exp(−b·SDD)], where b is a constant

Dependence of the Registered Blood Flow in Incoherent Optical Fluctuation Flowmetry on the Mean Photon Path Length in a Tissue

Laser-based medical techniques for evaluating blood flow (BF), such as laser Doppler flowmetry, laser speckle contrast imaging, etc., are known, but expensive and have some disadvantages. Recently, we have proposed a new technique—incoherent optical fluctuation flowmetry (IOFF), which is realized using a LED-based optical probe. This work aims to theoretically study the dependence of BF registered by IOFF on the source-detector distance (SDD) in the probe. For this purpose, we developed a three-layer optical model of skin and used Monte Carlo (MC) simulations of light propagation. All computations were performed for a wavelength of 810 nm and several SDDs from 1 to 14 mm. MC results showed that the BF depends nonlinearly on the SDD. Herewith, the BF is strongly correlated with the mean photon path length in a tissue (R = 0.92). Thus, flowmeters with different SDDs can give different BF values on the same patient. Based on the study results, to standardize BF measurements, it has been justified that BF magnitudes measured should be normalized to the exponential function of the SDD in the used optical probe in the form of [1 − exp(−b·SDD)], where b is a constant

Microstructure and properties of a nanostructured W-31 wt% Cu composite produced by magnetic pulse compaction of bimetallic nanoparticles

Nanostructured W-31wt.%Cu composite was for the first time produced via magnetic pulse compaction from bimetallic particles obtained using electric explosion of intertwisted copper/tungsten wires in argon and then characterized for microstructures, mechanical strength and tribological behavior at high temperatures. Microstructure of the composite is characterized by recrystallized copper grains with mean grain size of 59 ± 3 nm and unreacted spherical tungsten particles. The composite density was in the range 93–99%. Flexural and compression strengths were 560 ± 10 and 1035 ± 150 MPa, respectively. Tribological high temperature tests showed that this composite develops reduced wear starting from the testing at 250 ◦C. Such an adaptation mechanisms is related to generation of copper tungstate CuWO4 on the worn surfaces