Electric field control of nonvolatile four-state magnetization at room temperature

We find the realization of large converse magnetoelectric (ME) effects at room temperature in a multiferroic hexaferrite Ba$_{0.52}$Sr$_{2.48}$Co$_{2}$Fe$_{24}$O$_{41}$ single crystal, in which rapid change of electric polarization in low magnetic fields (about 5 mT) is coined to a large ME susceptibility of 3200 ps/m. The modulation of magnetization then reaches up to 0.62 $\mu$$_{B}$/f.u. in an electric field of 1.14 MV/m. We find further that four ME states induced by different ME poling exhibit unique, nonvolatile magnetization versus electric field curves, which can be approximately described by an effective free energy with a distinct set of ME coefficients

High Density, Localized Quantum Emitters in Strained 2D Semiconductors

Two-dimensional chalcogenide semiconductors have recently emerged as a host material for quantum emitters of single photons. While several reports on defect and strain-induced single photon emission from 2D chalcogenides exist, a bottom-up, lithography-free approach to producing a high density of emitters remains elusive. Further, the physical properties of quantum emission in the case of strained 2D semiconductors are far from being understood. Here, we demonstrate a bottom-up, scalable, and lithography-free approach to creating large areas of localized emitters with high density (~150 emitters/um2) in a WSe2 monolayer. We induce strain inside the WSe2 monolayer with high spatial density by conformally placing the WSe2 monolayer over a uniform array of Pt nanoparticles with a size of 10 nm. Cryogenic, time-resolved, and gate-tunable luminescence measurements combined with near-field luminescence spectroscopy suggest the formation of localized states in strained regions that emit single photons with a high spatial density. Our approach of using a metal nanoparticle array to generate a high density of strained quantum emitters opens a new path towards scalable, tunable, and versatile quantum light sources.Comment: 45 pages, 20 figures (5 main figures, 15 supporting figures

Roles of peroxiredoxin II in the regulation of proinflammatory responses to LPS and protection against endotoxin-induced lethal shock

Mammalian 2-Cys peroxiredoxin II (Prx II) is a cellular peroxidase that eliminates endogenous H2O2. The involvement of Prx II in the regulation of lipopolysaccharide (LPS) signaling is poorly understood. In this report, we show that LPS induces substantially enhanced inflammatory events, which include the signaling molecules nuclear factor κB and mitogen-activated protein kinase (MAPK), in Prx II–deficient macrophages. This effect of LPS was mediated by the robust up-regulation of the reactive oxygen species (ROS)–generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and the phosphorylation of p47phox. Furthermore, challenge with LPS induced greater sensitivity to LPS-induced lethal shock in Prx II–deficient mice than in wild-type mice. Intravenous injection of Prx II–deficient mice with the adenovirus-encoding Prx II gene significantly rescued mice from LPS-induced lethal shock as compared with the injection of a control virus. The administration of catalase mimicked the reversal effects of Prx II on LPS-induced inflammatory responses in Prx II–deficient cells, which suggests that intracellular H2O2 is attributable, at least in part, to the enhanced sensitivity to LPS. These results indicate that Prx II is an essential negative regulator of LPS-induced inflammatory signaling through modulation of ROS synthesis via NADPH oxidase activities and, therefore, is crucial for the prevention of excessive host responses to microbial products

Selective clamping hand-assisted laparoscopic partial nephrectomy for localized renal tumors: A novel technique

Purpose: In this study, we described our initial experience and analyze the learning curve of segmental renal artery branch clamping with hand-assisted laparoscopic partial nephrectomy (PN) using special instruments. Materials and Methods: We conducted a retrospective review of consecutive cases of hand-assisted laparoscopic PN (LPN) between May 2015 and April 2018. Patient demographics, tumor characteristics, perioperative details, postoperative complications, and warm ischemic time for segmental artery branch clamping were included in our analysis. We used the cumulative sum (CUSUM) method to generate learning curves. Results: Segmental renal artery branch clamping was successfully completed in 16 of 20 patients. The median tumor size was 2.9 cm (range, 1.7–7.0 cm), median operation time was 185 minutes (range, 140–245 minutes), median blood loss was 291 mL (range, 100–600 mL), and median hospital stay was 5 days (range, 4–7 days). The median selective ischemic time was 21 minutes (range, 16–35 minutes). No patient had postoperative complications, acute or delayed bleeding. The median pre- and postoperative serum creatinine levels (0.91 and 0.98 mg/dL, respectively), and the pre- and postoperative estimated glomerular filtration rate (89.7 and 79.6 mL/min per 1.73 m2, respectively) were similar. Upon visual assessment of the CUSUM plots, a downward inflection point for decreasing total operation time was observed in the 9th case and estimated blood loss in the 12th case. Conclusions: Our study shows that segmental renal artery branch clamping hand-assisted LPN for localized renal tumors is feasible, safe, and has a relatively short learning curve

Enhancement of the helical twisting power with increasing the terminal chain length of nonchiral bent-core molecules doped in a chiral nematic liquid crystal

In this work, we prepared a series of nonchiral bent-core molecules with different terminal alkoxy chain lengths, and measured the helical twisting power (HTP) of the bent-core molecules doped in a chiral nematic liquid crystal (N*LC). We investigated the doping effect through the colour change and spectral change due to the Bragg (selective) reflection and found that the bent-core molecules with longer alkoxy chains showed stronger HTP under chiral circumstances such as N*LC. Namely, not only the axial conformations at wings linked to the bent central unit but also the length of the alkoxy chains at the terminal positions of the bent-core molecules play an important role in the resulting unusual chiral behaviour. A preliminary stochastic dynamics simulation to determine the distribution of the chirality order parameters was made, being consistent with the present experimental result

Replacement of Ni by Mn in High-Ni-Containing Austenitic Cast Steels used for Turbo-Charger Application

High-temperature tensile properties of austenitic cast steels fabricated by replacing Ni by Mn in a 20 wt pct Ni-containing steel were investigated. In a steel where 8 wt pct Ni was replaced by 9.2 wt pct of Mn, 17.4 and 9.8 pct of ferrite existed in equilibrium phase diagrams and actual microstructures, respectively, because a role of Mn as an austenite stabilizer decreased, and led to deterioration of high-temperature properties. When 2 to 6 wt pct Ni was replaced by 2.3 to 6.9 wt pct Mn, high-temperature properties were comparable to those of the 20 wt pct Ni-containing steel because ferrites were absent, which indicated the successful replacement of 6 wt pct Ni by Mn, with cost reduction of 27 pct.11sciescopu

Polymer Stabilization of Liquid-Crystal Blue Phase II toward Photonic Crystals

The temperature ranges where a pure simple-cubic blue phase (BPII) emerges are quite narrow compared to the body-centered-cubic BP (BPI) such that the polymer stabilization of BPII is much more difficult. Hence, a polymer-stabilized BPII possessing a wide temperature range has been scarcely reported. Here, we fabricate a polymer-stabilized BPII over a temperature range of 50 °C including room temperature. The fabricated polymer-stabilized BPII is confirmed via polarized optical microscopy, Bragg reflection, and Kossel diagram observations. Furthermore, we demonstrate reflective BP liquid-crystal devices utilizing the reflectance–voltage performance as a potential application of the polymer-stabilized BPII. Our work demonstrates the possibility of practical application of the polymer-stabilized BPII to photonic crystals

Serotonin inhibits GABA synaptic transmission in presympathetic paraventricular nucleus neurons

Activation of serotonin (5-hydroxytryptamine, 5-HT) receptors produces various autonomic and neuroendocrine responses in the hypothalamic paraventricular nucleus (PVN), including increased blood pressure and heart rate. However, the role(s) of 5-HT on the local GABA synaptic circuit have not been well understood in the PVN, where the inhibitory neurotransmitter GABA plays a key role in the modulation of sympathoexcitatory outflow. In the present study, we examined the effects of 5-HT on GABA synaptic transmission in presympathetic PVN neurons projecting to spinal cord using patch-clamp electrophysiology combined with tract-tracing techniques. Bath application of 5-HT (0.01–100 μM) reversibly decreased the frequency of spontaneous GABAergic inhibitory postsynaptic currents (sIPSC) in a concentration dependent manner (IC50, 0.07 μM), with no significant changes in the amplitudes and decay kinetics of sIPSC. The sIPSC inhibition of 5-HT was mimicked by 5-HT1A agonist, 8-OH-DPAT (8-hydroxy-2(di-n-propylamino)tetralin, 10 μM), and blocked by 5-HT1A antagonist WAY-100635 but not by 5-HT1B antagonist SB224289. 5-HT also reduced the frequency of miniature IPSC (mIPSC) (2.59 ± 0.51 Hz, control vs. 1.25 ± 0.31 Hz, 5-HT, n = 16) in similar extent with 5-HT induced reduction of sIPSC frequency (sIPSCs, 55.8 ± 6.2%, n = 11 vs. mIPSCs, 52.30 ± 5.85%, n = 16; p > 0.5). All together, our results indicate that 5-HT can inhibit presynaptic GABA release via presynaptic 5-HT1A receptors in presympathetic PVN neurons projecting to spinal cord.We thank Dr. Javier Stern (University of Cincinnati) for the critical reading of the manuscript. This work was supported by research fund of Chungnam National University to J.B. Park

Microwave-assisted solvothermal synthesis of nanostructured Ga-Doped Li7La3Zr2O12 solid electrolyte with enhanced densification and Li-ion conductivity

Garnet-type Li7La3Zr2O12 (LLZO) Li-ion solid electrolytes are promising candidates for safe, next-generation solid-state batteries. In this study, we synthesize Ga-doped LLZO (Ga–LLZO) electrolytes using a microwave-assisted solvothermal method followed by low-temperature heat treatment. The nanostructured precursor (<50 nm) produced by the microwave-assisted solvothermal process has a high surface energy, facilitating the reaction for preparing garnet-type Ga–LLZO powders (<800 nm) within a short time (<5 h) at a low calcination temperature (<700 °C). Additionally, the calcined nanostructured Ga–LLZO powder can be sintered to produce a high-density pellet with minimized grain boundaries under moderate sintering conditions (temperature: 1150 °C, duration: 10 h). The optimal doping concentration was determined to be 0.4 mol% Ga, which resulted significantly increased the ionic conductivity (1.04 × 10−3 S cm−1 at 25 °C) and stabilized the cycling performance over 1700 h at 0.4 mA cm−2. This approach demonstrates the potential to synthesize oxide-type solid electrolyte materials with improved properties for solid-state batteries