Dynamic Acoustic Beamshaping with Coupling-Immune Moiré Metasurfaces.

Moiré effects arising from mutually twisted metasurfaces have showcased remarkable wave manipulation capabilities, unveiling tantalizing emerging phenomena such as acoustic moiré flat bands and topological phase transitions. However, the pursuit of strong near-field coupling in layers has necessitated acoustic moiré metasurfaces to be tightly stacked at narrow distances in the subwavelength range. Here, moiré effects beyond near-field interlayer coupling in acoustics are reported and the concept of coupling-immune moiré metasurfaces is proposed. Remote acoustic moiré effects decoupled from the interlayer distance are theoretically, numerically, and experimentally demonstrated. Tunable out-of-plane acoustic beam scanning is successfully achieved by dynamically controlling twist angles. The engineered coupling-immune properties are further extended to multilayered acoustic moiré metasurfaces and manipulation of acoustic vortices. Good robustness against external disturbances is also observed for the fabricated coupling-immune acoustic moiré metasurfaces. The presented work unlocks the potential of twisted moiré devices for out-of-plane acoustic beam shaping, enabling practical applications in remote dynamic detection, and multiplexed underwater acoustic communication.

[Risk factors for delayed bleeding after intestinal polypectomy in children]. / å„¿ç«¥è‚ æ¯è‚‰åˆ‡é™¤æœ¯åŽè¿Ÿå‘æ€§å‡ºè¡€çš„å±é™©å› ç´ åˆ†æž.

OBJECTIVES: To investigate the clinical characteristics and risk factors of delayed bleeding after intestinal polypectomy in children, and to provide a theoretical basis for clinical surgical intervention of intestinal polyps. METHODS: A retrospective analysis was conducted on the clinical data of 2 456 children with intestinal polyps who underwent endoscopic high-frequency electrocoagulation loop resection in the Endoscopy Center of Children's Hospital Affiliated to Zhengzhou University from January 2014 to December 2021. According to the presence or absence of delayed bleeding after surgery, they were divided into bleeding group with 79 children and non-bleeding group with 2 377 children. A multivariate logistic regression analysis was used to investigate the risk factors for delayed bleeding. The receiver operating characteristic (ROC) curve was used to investigate the value of various indicators in predicting delayed bleeding. RESULTS: Of all 2 456 children, 79 (3.22%) experienced delayed bleeding, among whom 5 children with severe delayed bleeding underwent emergency colonoscopy for hemostasis and 74 received conservative treatment, and successful hemostasis was achieved for all children. There were significant differences between the bleeding and non-bleeding groups in age, body mass index, constipation rate, location of lesion, time of endoscopic procedure, resection method (P<0.05). Children with a diameter of polyps of 6-10 mm and >20 mm were more likely to develop delayed bleeding after resection (P<0.05). The multivariate logistic regression analysis showed that endoscopic operation time, polyp diameter, and resection method were significantly associated with delayed bleeding (P<0.05). The ROC curve analysis showed that the endoscopic operation time, polyp diameter, and resection method had a good value in predicting delayed bleeding after intestinal polypectomy, with an area under the ROC curve of 0.706, 0.688, and 0.627, respectively. CONCLUSIONS: Endoscopic high-frequency electrocoagulation loop resection has a lower incidence of delayed bleeding in children with intestinal polyps, and the endoscopic operation time, polyp diameter, and resection method are closely associated with the occurrence of postoperative delayed bleeding.

Hybrid Metasurfaces for Perfect Transmission and Customized Manipulation of Sound Across Water-Air Interface.

Extreme impedance mismatch causes sound insulation at water-air interfaces, limiting numerous cross-media applications such as ocean-air wireless acoustic communication. Although quarter-wave impedance transformers can improve transmission, they are not readily available for acoustics and are restricted by the fixed phase shift at full transmission. Here, this limitation is broken through impedance-matched hybrid metasurfaces assisted by topology optimization. Sound transmission enhancement and phase modulation across the water-air interface are achieved independently. Compared to the bare water-air interface, it is experimentally observed that the average transmitted amplitude through an impedance-matched metasurface at the peak frequency is enhanced by ≈25.9 dB, close to the limit of the perfect transmission 30 dB. And nearly 42 dB amplitude enhancement is measured by the hybrid metasurfaces with axial focusing function. Various customized vortex beams are experimentally realized to promote applications in ocean-air communication. The physical mechanisms of sound transmission enhancement for broadband and wide-angle incidences are revealed. The proposed concept has potential applications in efficient transmission and free communication across dissimilar media.

Nano-gold micelles loaded Dox and Elacridar for reversing drug resistance of breast cancer.

The aim of this study was to provide a new effective carrier for rescuing the sensitivity of drug-resistant in breast cancer cells. Nano-gold micelles loaded with Dox and Elacridar (FP-ssD@A-E) were chemically synthesised. With the increase in the amount of Dox and Elacridar, the encapsulation rate of FP-ssD@A-E gradually increased, and the drug loading rate gradually decreased. FP-ss@A-E had a sustained-release effect. Dox, Elacridar, FP-ss@AuNPs, and FP-ssD@A-E significantly improved cell apoptosis, in which, FP-ssD@A-E was the most significant. FP-ssD@A-E significantly decreased the cell viability and improved the Dox uptake. The levels of VEGFR-1, P-gp, IL-6, and i-NOS were significantly decreased after Dox, Dox + Elacridar, FP-ss@AuNPs, and FP-ssD@A-E treatment. It was worth noting that FP-ssD@A-E had the most significant effects. The prepared FP-ssD@A-E micelles, which were spherical in shape, uniform in particle size distribution, and had good drug loading performance and encapsulation efficiency.

Identification of the active triple-phase boundary of a non-Pt catalyst layer in fuel cells.

The rational design of non-Pt oxygen reduction reaction (ORR) catalysts and catalyst layers in fuel cells is largely impeded by insufficient knowledge of triple-phase boundaries (TPBs) in the micropore and mesopore ranges. Here, we developed a size-sensitive molecular probe method to resolve the TPB of Fe/N/C catalyst layers in these size ranges. More than 70% of the ORR activity was found to be contributed by the 0.8- to 2.0-nanometer micropores of Fe/N/C catalysts, even at a low micropore area fraction of 29%. Acid-alkaline interactions at the catalyst-polyelectrolyte interface deactivate the active sites in mesopores and macropores, resulting in inactive TPBs, leaving micropores without the interaction as the active TPBs. The concept of active and inactive TPBs provides a previously unidentified design principle for non-Pt catalyst and catalyst layers in fuel cells.

A Nonlinear Magnetoelastic Energy Model and Its Application in Domain Wall Velocity Prediction.

In this letter, we propose a nonlinear Magnetoelastic Energy (ME) with a material parameter related to electron interactions. An attenuating term is contained in the formula of the proposed nonlinear ME, which can predict the variation in the anisotropic magneto-crystalline constants induced by external stress more accurately than the classical linear ME. The domain wall velocity under stress and magnetic field can be predicted accurately based on the nonlinear ME. The proposed nonlinear ME model is concise and easy to use. It is important in sensor analysis and production, magneto-acoustic coupling motivation, magnetoelastic excitation, etc.

Achromatic metasurfaces by dispersion customization for ultra-broadband acoustic beam engineering.

Metasurfaces, the ultra-thin media with extraordinary wavefront modulation ability, have shown great promise for many potential applications. However, most of the existing metasurfaces are limited by narrow-band and strong dispersive modulation, which complicates their real-world applications and, therefore require strict customized dispersion. To address this issue, we report a general methodology for generating ultra-broadband achromatic metasurfaces with prescribed ultra-broadband achromatic properties in a bottom-up inverse-design paradigm. We demonstrate three ultra-broadband functionalities, including acoustic beam deflection, focusing and levitation, with relative bandwidths of 93.3%, 120% and 118.9%, respectively. In addition, we reveal a relationship between broadband achromatic functionality and element dispersion. All metasurface elements have anisotropic and asymmetric geometries with multiple scatterers and local cavities that synthetically support internal resonances, bi-anisotropy and multiple scattering for ultra-broadband customized dispersion. Our study opens new horizons for ultra-broadband highly efficient achromatic functional devices, with promising extension to optical and elastic metamaterials.

miR-515-5p inhibits the proliferation, migration and invasion of human breast cancer cells by targeting CBX4.

microRNA (miR)-515-5p has been previously suggested to function as a tumor suppressor in various types of human cancer. Therefore, the role of miR-515-5p in breast cancer (BC) was explored in the present study. A series of assays were performed to study the function of miR-515-p in BC cells, including Cell Counting Kit-8, TUNEL, flow cytometric and colony formation to detect cell viability and apoptosis, wound healing and Transwell assays to measure cell motility. In addition, reverse transcription quantitative PCR and western blot analysis were used to assess miR-515-5p, CBX4, Cox-2, MMP2, MMP9, CDK2, p21 and Cyclin D1 respectively. Bioinformatics and dual-luciferase reporter assays were used to analyze the target genes of miR-515-5p, which confirmed the direct binding between miR-515-5p and polycomb chromobox 4 (CBX4). It was found that the expression of miR-515-5p is lower in BC cells compared with that in normal breast cells (MCF10A). Overexpression of miR-515-5p using the miR-515 mimic was found to reduce cell viability, facilitate cell apoptosis, inhibit cell proliferation and arrest cell cycle progressio at G1 phase. In addition, miR-515-5p overexpression could inhibit cell migration and invasion, whilst decreasing the expression levels of prostaglandin-endoperoxide synthase 2, MMP2 and MMP9 proteins. In addition, miR-515-5p overexpression could reduce the expression levels of CBX4 in MCF7 and ZR-75-30 cells. By contrast, overexpression of CBX4 reversed the effects of the miR-515-5p mimic transfection on cell proliferation, migration and invasion in MCF7 and ZR-75-30 cells. In combination, these results suggest that miR-515-5p inhibits BC cell proliferation, migration and invasion by directly targeting CBX4.

Electro-mechanical coupling diode of elastic wave in nonlinear piezoelectric metamaterials.

In this investigation, the bandgaps and nonreciprocal transmission of the nonlinear piezoelectric phononic crystal and elastic wave metamaterial are studied. Analytical solutions for the wave motion equations with the electro-mechanical coupling are obtained. According to the continuous conditions, the stop bands and transmission coefficients of both fundamental wave and second harmonic are derived by the stiffness matrix method. Some particular examples are presented to show the nonreciprocal transmission of the nonlinear elastic waves. Additionally, nonlinear ultrasonic experiments are applied to verify the theoretical analyses and numerical simulations. This work is intended to be helpful in the design and fabrication of devices of the elastic wave diode with piezoelectric materials.

Occupational radiation exposure of orthopedists at different locations during pedicle screw insertion: An anthropomorphic phantom study.

BACKGROUND: The purpose of this work was to evaluate orthopedic surgeons' exposure to occupational radiation doses from scattering using a mobile flat panel C-arm X-ray machine at different standing positions during an intraoperative pedicle screw implantation. OBJECTIVE: Evaluate the radiation dose received by medical staff, by applying flat X-ray machine in surgical room during an intraoperative pedicle screw implantation. METHODS: A mobile flat-panel C-arm X-ray machine at a dedicated orthopedic operating room was used to image an anthropomorphic female phantom which was set in a prone position on the operating table. The X-ray was projected horizontally, and 1 minute continuous fluoroscopy was used for lumbar spine and thoracolumbar spine during pedicle screw implantation. Scattering radiation doses to orthopedic surgeons were measured at different standing positions and body heights (50, 100, 150 cm above the ground) with and without limited collimations. RESULTS: The dose area product (DAP) in this experiment is normalized as 343 µGy⋅m2. In the four areas, the lowest scattered radiation measured by DF is 11.2 vs. 0.7 µSv, outside and inside the lead suit, respectively, with or without restricted field, 150 cm above the ground, and the lowest scattered radiation dose inside the lead suit. It is 1.3 vs. 0.5 µSv. Comparing the highest dose of the TF at with the lowest dose of the DF, the average result is 73.7 vs. 11.1 µSv, P< 0.05. CONCLUSIONS: Using a mobile flat-panel C-arm X-ray machine during a pedicle screw implantation, the minimum scattering radiation to surgeons was found to be at the terminal DF area based on the analysis of the scattering doses orthopedic surgeons were exposed to.

Tunable mechanical diode of nonlinear elastic metamaterials induced by imperfect interface.

In this investigation, the non-reciprocal transmission in a nonlinear elastic metamaterial with imperfect interfaces is studied. Based on the Bloch theorem and stiffness matrix method, the band gaps and transmission coefficients with imperfect interfaces are obtained for the fundamental and double frequency cases. The interfacial influences on the transmission behaviour are discussed for both the nonlinear phononic crystal and elastic metamaterial. Numerical results for the imperfect interface structure are compared with those for the perfect one. Furthermore, experiments are performed to support the theoretical analysis. The present research is expected to be helpful to design tunable devices with the non-reciprocal transmission and diode behaviour of the elastic metamaterial.

Broadband square cloak in elastic wave metamaterial plate with active control.

Cloaking invisibility is a novel technique that prevents the object from being detected in the background field. The development of new artificial materials and structures promotes the emergence of new achievements in cloaking research. In this work, a broadband square cloaking configuration of elastic wave metamaterial plate is designed and fabricated by the external active control system. The approximate parameters of the flexural wave cloak can be obtained by the coordinate transformation and achieved by alternating layers of the Acrylonitrile Butadiene Styrene (ABS), polydimethylsiloxane (PDMS), and piezoelectric (PZT) patches. With the introduction of active control systems, the square cloak has a wide effective frequency range. The simulation and experimental results show that the square cloak of flexural waves exhibits a good invisible performance in the frequency region of 500-2200 Hz. Compared to the structure without active control systems, the frequency region 2200-2750 Hz is extended for the active cloak. The design and fabrication of the broadband cloak is wished to be helpful during the practical engineering.

Elastic wave cloak and invisibility of piezoelectric/piezomagnetic mechanical metamaterials.

In this paper, a piezoelectric cloaking mechanism is proposed, which makes the enclosed piezomagnetic cylinder invisible to elastic shear horizontal (SH) waves. Based on the scattering cancellation technique, the piezoelectric cloaking mechanism and dynamic stress concentration factor (DSCF) is obtained by the plane wave expansion method. A nonlinear ray trajectory equation for SH waves is derived based on the nonlinear transformation. Furthermore, piezoelectric effects on both cloaking mechanism and dynamic stress concentration are analyzed. The numerical results show that the scattering cancellation can be attributed to the cloak density, and the piezoelectric property can enhance the object's invisibility. The piezoelectric cloaking design can be applied to reduce the DSCF in some frequency regions, which means that it can change the stress distribution. It means that piezoelectric scattering cancellation can enhance both the cloaking results and structural strength of the mechanical metamaterials. This study is expected to have significance for the development and design of elastic wave metamaterials.

[Complications of upper gastrointestinal foreign body in children and related risk factors].

OBJECTIVE: To study the complications of upper gastrointestinal foreign body in children and related risk factors. METHODS: Clinical data were collected from 772 children with upper gastrointestinal foreign bodies who were treated at the outpatient service or were hospitalized from January 2014 to December 2018. A multivariate logistic regression analysis was used to investigate the risk factors for the development of complications in children with upper gastrointestinal foreign bodies. RESILTS: The upper gastrointestinal foreign bodies were taken out by electronic endoscopy for the 772 children. There were 414 boys and 358 girls, with a median age of 2.8 years. Children under 3 years old accounted for 59.5%. The foreign bodies were mainly observed in the esophagus (57.5%) and the stomach (28.9%), with a retention time of ≤24 hours in 465 children (60.2%) and >24 hours in 307 children (39.8%). The types of upper gastrointestinal foreign bodies mainly included round metal foreign bodies (37.2%), long foreign bodies (24.7%), sharp foreign bodies (16.2%), batteries (14.4%), corrosive substances (4.8%), and magnets (2.7%). As for the severity of complications, 47.7% (368 children) had mild complications, 12.7% (98 children) had serious complications, and 39.6% (306 children) had no complications. The logistic regression analysis showed that an age of <3 years, underlying diseases, location of foreign body, type of foreign body, and a retention time of >24 hours were risk factors for the development of complications in these children (OR=2.141, 7.373, 6.658, 8.892, and 6.376 respectively, P<0.05). CONCLUSIONS: An understanding of the above high-risk factors for the complications of upper gastrointestinal foreign bodies is helpful to choose appropriate intervention methods and thus reduce the incidence of serious complications.

Active control on topological immunity of elastic wave metamaterials.

The topology concept in the condensed physics and acoustics is introduced into the elastic wave metamaterial plate, which can show the topological property of the flexural wave. The elastic wave metamaterial plate consists of the hexagonal array which is connected by the piezoelectric shunting circuits. The Dirac point is found by adjusting the size of the unit cell and numerical simulations are illustrated to show the topological immunity. Then the closing and breaking of the Dirac point can be generated by the negative capacitance circuits. These investigations denote that the topological immunity can be achieved for flexural wave in mechanical metamaterial plate. The experiments with the active control action are finally carried out to support the numerical design.

Porous Carbon Membrane-Supported Atomically Dispersed Pyrrole-Type FeN4 as Active Sites for Electrochemical Hydrazine Oxidation Reaction.

The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe-Nx sites supported by hierarchically porous carbon membranes are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe-Nx single-atom catalyst together with the uniquely mixed micro-/macroporous membrane support positions such an electrode among the best-known heteroatom-based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole-type FeN4 structure is identified as the real catalytic site in HzOR.

Comparison of Bioelectrical Impedance Analysis and Dual Energy X-ray Absorptiometry for Total and Segmental Bone Mineral Content with a Three-Compartment Model.

Modern bioelectrical impedance analysis (BIA) provides a wide range of body composition estimates such as fat mass (FM), lean body mass (LBM), and body water, using specific algorithms. Assuming that the fat free mass (FFM) and LBM can be accurately estimated by the 8-electrode BIA analyzer (BIA8MF; InBody230, Biospace), the bone mineral content (BMC) may be calculated by subtracting the LBM from the FFM estimates based on the three-compartment (3C) model. In this cross-sectional study, 239 healthy Taiwanese adults (106 male and 133 female) aged 20-45 years were recruited for BIA and dual-energy X-ray absorptiometry (DXA) measurements of the whole body and body segments, with DXA as the reference. The results showed a high correlation between BIA8MF and DXA in estimating total and segmental LBM, FM and percentage body fat (r = 0.909-0.986, 0.757-0.964, and 0.837-0.936, respectively). For BMC estimates, moderate to high correlations (r = 0.425-0.829) between the two methods were noted. The percentage errors and pure errors for BMC estimates between the methods ranged from 33.9% to 93.0% and from 0.159 kg to 0.969 kg, respectively. This study validated that BIA8MF can accurately assesses LBM, FM and body fat percentage (BF%). However, the estimation of segmental BMC based on the difference between FFM and LBM in body segments may not be reliable by BIA8MF.

Modulation of out-of-plane reflected waves by using acoustic metasurfaces with tapered corrugated holes.

In this paper, modulation of reflected wavefront out of the incident plane by a tunable acoustic metasurface is investigated based on the fully generalized Snell's law in the three-dimensional space. The metasurface is constructed by a square lattice of circular holes with gradient annular bumps. The phase shift is tuned by changing the volume of water filled in the holes. The acoustic wave steering out of the incident plane and the out-of-plane acoustic focusing with the oblique incidence at the subwavelength scale are demonstrated numerically by selecting suitable distributions of water depth. The numerical results show that the wavefront of the reflected wave can be manipulated over a wide frequency range; and the gradient design of the unit cells can suppress the parasitic reflection. The present work is relevant to the practical design of novel acoustic devices.

Active control on switchable waveguide of elastic wave metamaterials with the 3D printing technology.

Propagation of elastic waves along a direction has special interests in practical applications. These concerns generate the design of an elastic wave metamaterial with electrically switchable properties, which is studied in this work. The structure contains a T-shaped waveguide in a plate with the 3D printing technology; and the active control system is used to tune the propagation direction of the flexural wave. The piezoelectric patches which are connected by the negative capacitance circuits are applied to behave as the active control system. The finite element simulation is performed to give the theoretical prediction of the switchable waveguide and the tunable equivalent parameters are achieved by the electrical circuits. The active control experiments are finally carried out to support the numerical design.

[Application of quality constant method in grade evaluation of Aurantii Fructus Immaturus pieces].

The grade classification of Chinese herbal medicines and their decoction pieces has always been a hot issue in the industry. In the trading history of Chinese herbal medicine,buyers and sellers often determine the price according to quality,so the naturally formed specifications and grades are changing with the change of technology and the increasing demand of the public for medical care.The planting,processing and circulation methods of Chinese medicinal materials have also changed greatly. Under the mode of pursuing yield and short-term benefit,the traditional rating evaluation method has been difficult to be used in the current quality status of prepared slices. Aurantii Fructus Immaturus is a genuine medicinal material of Jiangxi province,which is widely used,but has different quality levels on the market. In this paper,the quality levels were evaluated by the mass constant method. A set of grading method of Aurantii Fructus Immaturus slices was established,laying a foundation for " high quality and high price" Aurantii Fructus Immaturus slices. The grading method of Chinese herbal slices with quality constant was applied to 16 batches of Aurantii Fructus Immaturus slices collected form the market,and the final assessment results were as follows for different piece shapes( hemispherical type and thin type)respectively. The hemispherical Aurantii Fructus Immaturus pieces: quality constant ≥1. 11 for the first grade,< 1. 11 but ≥0. 69 for the second grade,and <0. 69 for the third grade. The thin type Aurantii Fructus Immaturus pieces: quality constant ≥0. 024 for the first grade,<0. 024 but ≥0. 015 for the second grade,and <0. 015 for the third grade. This work indicated that the quality constants grading method can be used to objectively classify the grades of traditional Chinese medicine,providing basis for standardizing market behavior and providing useful reference for grading of hemispherical or thin Aurantii Fructus Immaturus pieces.