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Much of the dramatic growth in research on topological materials has focused on topologically protected surface states. While the domain walls of topological materials such as Weyl semimetals with broken inversion or time-reversal symmetry can provide a hunting ground for exploring topological interfacial states, such investigations have received little attention to date. Here, utilizing in-situ cryogenic transmission electron microscopy combined with first-principles calculations, we discover intriguing domain-wall structures in MoTe 2 , both between polar variants of the low-temperature( T ) Weyl phase, and between this and the high- T higher-order topological phase. We demonstrate how polar domain walls can be manipulated with electron beams and show that phase domain walls tend to form superlattice-like structures along the c axis. Scanning tunneling microscopy indicates a possible signature of a conducting hinge state at phase domain walls. Our results open avenues for investigating topological interfacial states and unveiling multifunctional aspects of domain walls in topological materials. Domain walls of topological materials may be good candidates to study topological interfacial states. Here, Huang et al. discover polar domain walls which can be manipulated by electron beams and phase domain walls where possible signature of a conducting hinge state is detected in Weyl semimetal MoTe 2 .

Allergens from domestic cats ( Felis catus ) cause allergy-related health problems worldwide. Fel d 1 is a major allergen that causes severe allergic reactions in humans, including rhinitis, conjunctivitis, and life-threatening asthma. Therefore, patients with cat allergies anticipate hypoallergenic cats. We successfully generated Fel d 1 chain 2 (CH2) genome-edited cats using the CRISPR-Cas9 system in this study. T7 endonuclease 1 assay and Sanger sequencing were used to confirm the mutation in CH2 genome-edited cats. Fel d 1 level in CH2 genome-edited cats were assessed by enzyme-linked immunosorbent assay (ELISA). Remarkably, ELISA showed that the level of Fel d 1 in the CH2 homozygous genome-edited cat (Name: Alsik) was extremely low compared with that in wild type domestic cats and could be hypoallergenic cats. Additionally, we successfully cloned the CH2 homozygous genome-edited cat using cytoplasm injection clone technology. The cloned CH2 homozygous genome-edited cat was verified using microsatellite analysis. Creating hypoallergenic cats using the CRISPR-Cas9 system is a significant step forward because these cats can safely approach allergic patients.

To achieve carbon neutrality by 2050, Korea has been expanding its investment in renewal energy distribution and technology development. However, with this rapid expansion of renewable energy, public concern about it has grown. This study developed and used a big data analysis-based procedure to analyze the questions registered on Naver, the largest portal site in Korea, from 2008 to 2020 to identify public concern over renewable energy. The big data analysis-based procedure consisted of two steps. The first was a frequency analysis to identify the most frequently registered words. The second was to classify questions using term frequency-inverse document frequency (TF-IDF) weight and cosine similarity based on word2vec. The analysis revealed the most frequently registered words related to renewable energy, such as “solar power,” “power generation,” “energy,” and “wind power.” It also revealed the most frequently registered questions, such as those related to solar panel installation, renewable energy generation methods, and certificates. To continue expanding renewable energy, it is becoming increasingly important to understand the public’s concerns and create a method to resolve their objections to renewable energy. It is expected that the procedure in this study may provide relevant insight for the method.

High-accuracy numerical simulations are performed to study aeroacoustic source mechanisms of wavy leading edges (WLEs) on a thin aerofoil undergoing vortical disturbances. This canonical study is based on a prescribed spanwise vortex travelling downstream and creating secondary vortices as it passes through the aerofoil’s leading edge. The primary aim of the study is to precisely understand the relationships between the vortex-induced velocity perturbation and the wall pressure fluctuation on the WLE geometry. It is observed that by increasing the size (amplitude) of the WLE the source strength at the peak region is reduced rapidly to a certain point, followed by a saturation stage, while at the root (trough) it remains fairly consistent regardless of the WLE size. This observation is demonstrated to be the consequence of three-dimensional vortex dynamics taking place along the WLE. One of the most profound features is that a system of horseshoe-like secondary vortices are created from the WLE peak region upon the impingement of the prescribed vortex. It is found that the horseshoe vortices produce a significantly non-uniform velocity perturbation in front of the WLE leading to the disparity in the source characteristics between the peak and root. The alterations to the impinging velocity perturbation are carefully analysed and related to the wall pressure fluctuation in this study. In addition, a semi-analytic model based on Biot–Savart’s law is developed to better understand and explain the role of the horseshoe vortex systems and the source mechanisms.

Oxygen octahedral distortions, including tilts/rotations, deformations and off-centring in (layered) perovskites, have the key role in their numerous functional properties. Near the polar-centrosymmetric phase boundary in bi-layered perovskite Ca 3− x Sr x Ti 2 O 7 with x ≈1, we found the presence of abundant topological eight-state vortex-antivortex pairs, associated with four oxygen octahedral tilts at domains and another four different oxygen octahedral tilts at domain walls. Our discovery opens a new revenue to unveil real-space topological defects associated with the possible vector choices in one specific lattice mode. Ferroelectrics: Coupled topological defects with a new state in perovskite Octahedral distortions have close links to the rich variety of functional properties exhibited by perovskite crystals. Sang-Wook Cheong of Rutgers University in the USA and co-workers report the discovery of a new symmetry state in the double-layered perovskite (Ca,Sr) 3 Ti 2 O 7 utilizing a combination of transmission electron microscopy, synchrotron x-ray diffraction and dielectric characterizations. This intermediate tetragonal structure appears in the vicinity of the phase transition boundary at which the increasing Ca doping drives the parent tetragonal Sr 3 Ti 2 O 7 unit cell to undergo an orthorhombic distortion. Associated with the oxygen octahedral tilts along the tetragonal directions in this new intermediate state, there are intriguing topological defects present, which may suggest an avenue towards the realization of unconventional functionalities ultimately.

A wall-resolved large-eddy simulation of a symmetric Joukowski aerofoil with a 12 % thickness at a Reynolds number of 250 000, a Mach number of 0.4 and zero incidence angle is performed in order to investigate the effect of using a serrated trailing edge on the acoustic feedback event that generates a tonal noise. The acoustic feedback is investigated in detail to emphasise the interaction between the upstream travelling acoustic expansion wave and the laminar separation bubble. The simulation shows that the serrated trailing edges may result in a significant reduction of the tonal noise. This paper provides detailed investigations into the noise reduction mechanisms. The main finding is that the presence of a serrated trailing edge decreases the amplitude of the acoustic source pressure in the transitional region and gives rise to destructive phase interference in the wall pressure fluctuations in the vicinity of the trailing edge which weakens the acoustic feedback loop.

The manipulation of magnetic ordering with applied electric fields is of pressing interest for new magnetoelectric devices and information storage applications. Recently, such magnetoelectric control was realized in multiferroics. However, their magnetoelectric switching is often accompanied by significant hysteresis, resulting from a large barrier, separating different ferroic states. Hysteresis prevents robust switching, unless the applied field overcomes a certain value (coercive field). Here we address the role of a switching barrier on magnetoelectric control, and identify a material, collinear antiferromagnetic and pyroelectric Ni 3 TeO 6 , in which magnetoelectric switching occurs without hysteresis. The barrier between two magnetic states in the vicinity of a spin–flop transition is almost flat, and thus small changes in external electric/magnetic fields allow to switch the ferroic state through an intermediate state in a continuous manner, resulting in a colossal magnetoelectric response. This colossal magnetoelectric effect resembles the large piezoelectric effect at the morphotropic phase boundary in ferroelectrics. Usually magnetoelectric switching is accompanied by hysteresis, which is a consequence of the large barrier between different magnetoelectric states. Here, the authors show that in the antiferromagnet Ni 3 TeO 6 magnetoelectric switching of magnetization as well as polarization occur without hysteresis.

The study of abrupt increases in magnetization with magnetic field known as metamagnetic transitions has opened a rich vein of new physics in itinerant electron systems, including the discovery of quantum critical end points with a marked propensity to develop new kinds of order. However, the electric analogue of the metamagnetic critical end point, a \"metaelectric\" critical end point, has been rarely studied. Multiferroic materials wherein magnetism and ferroelectricity are cross-coupled are ideal candidates for the exploration of this novel possibility using magnetic-field (H) as a tuning parameter. Herein, we report the discovery of a magnetic-field-induced metaelectric transition in multiferroic BiMn₂O₅, in which the electric polarization (P) switches polarity along with a concomitant Mn spin-flop transition at a critical magnetic field Hc. The simultaneous metaelectric and spin-flop transitions become sharper upon cooling but remain a continuous cross-over even down to 0.5 K. Near the P = 0 line realized at μ₀Hc [almost equal to] 18 T below 20 K, the dielectric constant (ε) increases significantly over wide field and temperature (T) ranges. Furthermore, a characteristic power-law behavior is found in the P(H) and ε(H) curves at T = 0.66 K. These findings indicate that a magnetic-field-induced metaelectric critical end point is realized in BiMn₂O₅ near zero temperature.

Mid-infrared wavelengths are called the molecular fingerprint region because it contains the fundamental vibrational modes inherent to the substances of interest. Since the mid-infrared spectrum can provide non-destructive identification and quantitative analysis of unknown substances, miniaturized mid-infrared spectrometers for on-site diagnosis have attained great concern. Filter-array based on-chip spectrometer has been regarded as a promising alternative. In this study, we explore a way of applying a pillar-type plasmonic nanodiscs array, which is advantageous not only for excellent tunability of resonance wavelength but also for 2-dimensional integration through a single layer process, to the multispectral filter array for the on-chip spectrometer. We theoretically and experimentally investigated the optical properties of multi-periodic triangular lattices of metal nanodiscs array that act as stopband filters in the mid-infrared region. Soft-mold reverse nanoimprint lithography with a subsequent lift-off process was employed to fabricate the multispectral filter array and its filter function was successfully extracted using a Fourier transform infrared microscope. With the measured filter function, we tested the feasibility of target spectrum reconstruction using a Tikhonov regularization method for an ill-posed linear problem and evaluated its applicability to the infrared spectroscopic sensor that monitors an oil condition. These results not only verify that the multispectral filter array composed of stopband filters based on the metal nanodiscs array when combined with the spectrum reconstruction technique, has great potential for use to a miniaturized mid-infrared on-chip spectrometer, but also provide effective guidance for the filter design.

The association between chronic laryngitis and tinnitus is not a well-studied topic, unlike the association of these two conditions with many other disorders. Cross-sectional data of 11,347 adults (males: 4,934; females: 6,413), who completed the Korea National Health and Nutrition Examination Survey (KNHANES) from 2010 to 2012 were used to investigate this association. Lifestyle patterns, including smoking and alcohol habits, regular exercise, physical and mental health status, socioeconomic status, nutritional status, and other chronic diseases, were analyzed. Chronic laryngitis and tinnitus were diagnosed by field survey teams, which included otolaryngologists, who conducted chronic disease surveillance using a health status interview, a nutritional status questionnaire, and a physical examination. Chronic laryngitis was significantly associated with age, education beyond high school, depressed mood, voice change, metabolic syndrome, and tinnitus in men. In women, chronic laryngitis was associated with body mass index and diabetes mellitus. Chronic laryngitis in men was significantly associated with tinnitus (odds ratio 1.671, [95% confidence interval: 1.167-2.393]) after adjusting for age, body mass index, smoking status, alcohol intake, regular exercise, metabolic syndrome, education beyond high school, and depressed mood. Additionally, the prevalence of chronic laryngitis increased with increasing severity of tinnitus in men alone (P = 0.002). The study revealed a significant association between chronic laryngitis and tinnitus.