Sr2_2IrO4_4/Sr3_3Ir2_2O7_7 superlattice for a model 2D quantum Heisenberg antiferromagnet

Spin-orbit entangled pseudospins hold promise for a wide array of exotic magnetism ranging from a Heisenberg antiferromagnet to a Kitaev spin liquid depending on the lattice and bonding geometry, but many of the host materials suffer from lattice distortions and deviate from idealized models in part due to inherent strong pseudospin-lattice coupling. Here, we report on the synthesis of a magnetic superlattice comprising the single ($n$=1) and the double ($n$=2) layer members of the Ruddlesden-Popper series iridates Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ alternating along the $c$-axis, and provide a comprehensive study of its lattice and magnetic structures using scanning transmission electron microscopy, resonant elastic and inelastic x-ray scattering, third harmonic generation measurements and Raman spectroscopy. The superlattice is free of the structural distortions reported for the parent phases and has a higher point group symmetry, while preserving the magnetic orders and pseudospin dynamics inherited from the parent phases, featuring two magnetic transitions with two symmetry-distinct orders. We infer weaker pseudospin-lattice coupling from the analysis of Raman spectra and attribute it to frustrated magnetic-elastic couplings. Thus, the superlattice expresses a near ideal network of effective spin-one-half moments on a square lattice

Risk factors for severe postpartum hemorrhage requiring blood transfusion after cesarean delivery for twin pregnancy: a nationwide cohort study

Background Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality. Twin pregnancy and cesarean delivery are well-known risk factors for PPH. However, few studies have investigated PPH risk factors in mothers who have undergone cesarean delivery for twin pregnancies. Therefore, this study investigated the risk factors associated with severe PPH after cesarean delivery for twin pregnancies. Methods We searched and reviewed the Korean Health Insurance Review and Assessment Service’s claims data from July 2008 to June 2021 using the code corresponding to cesarean delivery for twin pregnancy. Severe PPH was defined as hemorrhage requiring red blood cell (RBC) transfusion during the peripartum period. The risk factors associated with severe PPH were identified among the procedure and diagnosis code variables and analyzed using univariate and multivariate logistic regressions. Results We analyzed 31,074 cesarean deliveries for twin pregnancies, and 4,892 patients who underwent cesarean deliveries for twin pregnancies and received RBC transfusions for severe PPH were included. According to the multivariate analysis, placental disorders (odds ratio, 4.50; 95% confidence interval, 4.09–4.95; P < 0.001), general anesthesia (2.33, 2.18–2.49; P < 0.001), preeclampsia (2.20, 1.99–2.43; P < 0.001), hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome (2.12, 1.22–3.68; P = 0.008), induction failure (1.37, 1.07–1.76; P = 0.014), and hypertension (1.31, 1.18–1.44; P < 0.001) predicted severe PPH. Conclusions Placental disorders, hypertensive disorders such as preeclampsia and HELLP syndrome, and induction failure increased the risk of severe PPH after cesarean delivery for twin pregnancy

Enzymatic properties of the Caenorhabditis elegans Dna2 endonuclease/helicase and a species-specific interaction between RPA and Dna2

In both budding and fission yeasts, a null mutation of the DNA2 gene is lethal. In contrast, a null mutation of Caenorhabditis elegans dna2(+) causes a delayed lethality, allowing survival of some mutant C.elegans adults to F2 generation. In order to understand reasons for this difference in requirement of Dna2 between these organisms, we examined the enzymatic properties of the recombinant C.elegans Dna2 (CeDna2) and its interaction with replication-protein A (RPA) from various sources. Like budding yeast Dna2, CeDna2 possesses DNA-dependent ATPase, helicase and endonuclease activities. The specific activities of both ATPase and endonuclease activities of the CeDna2 were considerably higher than the yeast Dna2 (∼10- and 20-fold, respectively). CeDna2 endonuclease efficiently degraded a short 5′ single-stranded DNA tail (<10 nt) that was hardly cleaved by ScDna2. Both endonuclease and helicase activities of CeDna2 were stimulated by CeRPA, but not by human or yeast RPA, demonstrating a species-specific interaction between Dna2 and RPA. These and other enzymatic properties of CeDna2 described in this paper may shed light on the observation that C.elegans is less stringently dependent on Dna2 for its viability than Saccharomyces cerevisiae. We propose that flaps generated by DNA polymerase δ-mediated displacement DNA synthesis are mostly short in C.elegans eukaryotes, and hence less dependent on Dna2 for viability

Improvements in structural and optical properties of wafer-scale hexagonal boron nitride film by post-growth annealing

Remarkable improvements in both structural and optical properties of wafer-scale hexagonal boron nitride (h-BN) films grown by metal-organic chemical vapor deposition (MOCVD) enabled by high-temperature post-growth annealing is presented. The enhanced crystallinity and homogeneity of the MOCVD-grown h-BN films grown at 1050 degrees C is attributed to the solid-state atomic rearrangement during the thermal annealing at 1600 degrees C. In addition, the appearance of the photoluminescence by excitonic transitions as well as enlarged optical band gap were observed for the post-annealed h-BN films as direct consequences of the microstructural improvement. The post-growth annealing is a very promising strategy to overcome limited crystallinity of h-BN films grown by typical MOCVD systems while maintaining their advantage of multiple wafer scalability for practical applications towards two-dimensional electronics and optoelectronics.11Ysciescopu

Effects of Cervical Sensorimotor Control Training on Pain, Function and Psychosocial Status in Patients With Chronic Neck Pain

Background: It is reported that the proprioceptive sensation of patients with neck pain is reduced, and neck sensory-motor control training using visual feedback is reported to be effective. Objects: The purpose of this study is to investigate how sensorimotor control training for the cervical spine affects pain, function, and psychosocial status in patients with chronic cervical pain. Methods: The subjects consisted of 36 adults (male: 15, female: 21) who had experienced cervical spine pain for more than 6 weeks. An exercise program composed of cervical stabilization exercise (10 minutes), electrotherapy (10 minutes), manual therapy (10 minutes), and cervical sensorimotor control training (10 minutes) was implemented for both the experimental and the control groups. The cervical range of motion (CROM) and head repositioning accuracy were assessed using a CROM device. In the experimental group, the subjects wore a laser device on the head to provide visual feedback while following pictures in front of their eyes; whereas, in the control group, the subjects had the same training of following pictures without the laser device. Results: There were no statistically significant differences between the two groups in pain, dysfunction, range of motion, or psychosocial status; however, post-test results showed significant decreases after 2 weeks and 4 weeks compared to baseline (p < 0.01), and after 4 weeks compared to after 2 weeks (p < 0.01). The cervical joint position sense differed significantly between the two groups (p < 0.05). Conclusion: In this study, visual feedback enhanced proprioception in the cervical spine, resulting in improved cervical joint position sense. On the other hand, there were no significant effects on pain, dysfunction, range of motion, or psychosocial status

Comparison of Infraspinatus and Posterior Deltoid Muscle Activities According to Exercise Methods and Forearm Positions During Shoulder External Rotation Exercises

Background: Shoulder external rotation exercises are commonly used to improve the stabi-lizing ability of the infraspinatus. However, during exercise, excessive activation of the poste-rior deltoid compared to the infraspinatus causes the humeral head to move anteriorly in an abnormal position. Many researchers have emphasized selective activation of the infraspina-tus during shoulder external rotation exercise.Objects: This study aims to delineate the optimal exercise method for selective activation of infraspinatus by investigating the muscle activities of the infraspinatus and posterior deltoid according to the four shoulder exercise methods and two forearm positions.Methods: Thirty healthy individuals participated in this study. The participants were instruct-ed to perform shoulder external rotation exercises following four exercise methods: sitting external rotation (SIER); standing external rotation at 90° abduction (STER); prone external ro-tation at 90° abduction (PRER); side-lying external rotation (SLER), and two forearm positions (neutral, supinated). The electromyography (EMG) signal amplitude was measured during each exercise. Surface EMG signals were recorded from the posterior deltoid, infraspinatus, and biceps brachii.Results: EMG results of the infraspinatus and posterior deltoid in PRER, were significantly higher than that of the other exercises (p < 0.01). The EMG ratio (infraspinatus/posterior deltoid) in SIER was significantly higher than that of the other exercises. EMG activation of the posterior deltoid in SIER, PRER, and SLER was significantly higher in neutral than in supinated (p < 0.01). Furthermore, the EMG of the infraspinatus in SIER was significantly higher in neu-tral than in supinated (p < 0.01). The EMG ratio (infraspinatus/ posterior deltoid) in SIER was significantly higher in neutral than in supinated (p < 0.05.) Contrarily EMG ratios in PRER and SLER were significantly higher in supinated than in neutral (p < 0.05).Conclusion: The results show that clinicians should consider these exercise methods and forearm positions when planning shoulder external rotation exercises for optimal shoulder rehabilitation

Designing efficient spin Seebeck-based thermoelectric devices via simultaneous optimization of bulk and interface properties

The spin Seebeck effect (SSE) refers to a direct energy conversion of heat to electricity that exploits magnon current in a ferromagnet (FM)/normal metal (NM) heterostructure. Since SSE is a transverse thermoelectric effect, it can be employed to realize transverse thermoelectric devices, which could potentially overcome the inherent limitations of conventional Seebeck effect-based devices. Yet, the widespread use of SSE is currently hindered by its low conversion efficiency. The thermoelectric efficiency of SSE can be improved through an optimization of bulk FM as well as FM/NM interface. A bulk FM can enhance the thermoelectric efficiency by introducing a &apos;phonon-glass magnon-crystal&apos; concept, wherein scattering centers selectively scatter the heat-carrying phonons while not affecting the magnons that contribute to SSE. A high-quality FM/NM interface can boost the spin pumping across the interface as well as the electrical transport in NM. Here, by adopting polycrystalline nickel-ferrite (NFO)/Pt as a platform, we demonstrate the successful optimization of bulk FM together with FM/NM interface via a simple heat treatment scheme. The phase separation of NFO via such heat treatment results in a distinctive hierarchical microstructure of nano-sized NFO embedded in micro-sized NiO precipitates; this structure selectively scatters phonons while barely affecting magnons, leading to reduced thermal conductivity without variation of spin Seebeck coefficient. The simultaneous formation of a clean and smooth NFO/Pt interface provides efficient spin pumping at the interface and high electrical conductivity of Pt. As a result, the energy conversion efficiency of SSE in NFO/Pt system can be significantly improved. The proposed facile approach can be applied to design highly efficient oxide-based SSE devices.11Nsciescopu

Microstructural development of cobalt ferrite ceramics and its influence on magnetic properties

The microstructural evolution and its influence on magnetic properties in cobalt ferrite were investigated. The cobalt ferrite powders were prepared via a solid-state reaction route and then sintered at 1200 A degrees C for 1, 2, and 16 h in air. The microstructures from sintered samples represented a bimodal distribution of grain size, which is associated with abnormal grain growth behavior. And thus, with increasing sintering time, the number and size of abnormal grains accordingly increased but the matrix grains were frozen with stagnant grain growth. In the sample sintered for 16 h, all of the matrix grains were consumed and the abnormal grains consequently impinged on each other. With the appearance of abnormal grains, the magnetic coercivity significantly decreased from 586.3 Oe (1 h sintered sample) to 168.3 Oe (16 h sintered sample). This is due to the magnetization in abnormal grains being easily flipped. In order to achieve high magnetic coercivity of cobalt ferrite, it is thus imperative to fabricate the fine and homogeneous microstructure.118sciescopuskc

Hyper stress induced charge generation in nano sized BaTiO3 particles below critical ferroelectric particle size

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