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Microhabitat factors play an important role in regulating bryophyte species distribution and the development of bryophyte-dominated biological soil crusts (hereafter bryophyte crusts). We investigated the distribution and development of bryophytes in eight microhabitats in the water-wind erosion crisscross region of the Loess Pla-teau. We used the line intercept transects to explore and quantify the influencing pathways of microhabitat factors on bryophyte diversity and analyzed the influencing pathways of plant cover, slope aspect, and slope gradient by using structural equation model to quantify influencing coefficients. Our results showed that: 1) The Patrick, Shannon, Pielou, and Simpson indcies of bryophytes under plant canopy were 63.4%, 66.6%, 91.0%, and 68.3% lower than that without plant canopy, respectively, while the thickness, biomass, and chlorophyll content of bryophyte crusts were 0.5, 0.2, and 1.3 times higher than that without plant canopy, respectively. 2) The Patrick, Shannon, Pielou, and Simpson indexes of bryophytes on the north slope were 0.6, 0.9, 5.6, and 0.9 times higher than those on the south slope, while the thickness, biomass, and chlorophyll content of bryophyte crusts were 0.3, 0.3, and 0.6 times higher than those on the south slope, respectively. 3) As the slope increasing from 14° to 34°, the Patrick, Shannon, Pielou, and Simpson indexes of bryophyte were decreased by 59.8%, 84.1%, 57.3% and 68.0%, and the thickness, biomass, and chlorophyll content of bryophyte crusts were decreased by 15.2%, 25.0%, and 16.5%, respectively. 4) The importance of the three microhabitat factors on bryophyte diversity and the development of bryophyte crusts followed an order of plant canopy coverslope aspectslope gradient. The primary influencing pathway varied among the microhabitat factors. In conclusion, plant cover, slope aspect, and slope gradient significantly affected the distribution of bryophytes species and developmental level of bryophyte crusts through direct and indirect pathways. Therefore, full consideration should be given to microhabitat conditions when using bryophyte crusts to control desertification.微生境因子对苔藓结皮的物种分布和发育有重要调控作用。为探明其作用途径和影响程度,以黄土高原水蚀风蚀交错区的苔藓结皮为研究对象,通过样线法调查了8种微生境中苔藓结皮的物种分布和发育特征,结合结构方程模型剖析了植物冠层覆盖、坡向和坡度对苔藓多样性和苔藓结皮发育的影响途径并量化了其影响系数。结果表明: 1)与无冠层相比,冠层覆盖使苔藓的Patrick、Shannon、Pielou和Simpson指数分别降低了63.4%、66.6%、91.0%和68.3%,但使苔藓结皮的厚度、生物量和叶绿素含量分别提高了0.5、0.2和1.3倍;2)北坡样地的4种苔藓物种多样性指数较南坡分别提高了0.6、0.9、5.6和0.9倍,而3种苔藓结皮发育指标分别提高了0.3、0.3和0.6倍;3)坡度从14°增加到34°,4种苔藓多样性指数分别降低了59.8%、84.1%、57.3%和68.0%,而3种苔藓结皮发育指标分别降低了15.2%、25.0%和16.5%;4)3种微生境因子对苔藓多样性和苔藓结皮发育的影响程度为冠层覆盖＞坡向＞坡度,其主要影响途径因微生境因子不同而存在差异。综上,植物冠层覆盖、坡度和坡向分异通过直接和间接途径显著影响了苔藓的物种分布和苔藓结皮发育,因此,在利用苔藓结皮进行荒漠化治理时应充分考虑微生境条件。.

We selected typical croplands in the black soil region of Northeast China to analyze the characteristics of biocrusts during the growing season, including species composition, thickness, coverage, and biomass (chlorophyll content). We collected bareground soil and biocrusts samples with chlorophyll content of 5-15, 15-25, 25-35, and 35-50 mg·g于作物生长季对东北黑土区典型农田中生物结皮的发育特征(类型、物种、厚度、覆盖度、生物量)进行分析,并使用数显推拉力计测定比较了无结皮土壤与不同生物量(以叶绿素含量表征,分别为5～15、15～25、25～35、35～50 mg·g

The changes in soil properties caused by grazing and trampling are important reasons for the changes in soil respiration rates, carbon fixation, and emission. However, the effects of different intensities of grazing and trampling on biocrusts respiration rate are unclear. In this study, we simulated grazing and trampling disturbances of 10%, 30%, 50%, and 70% intensity on moss biocrusts developed in aeolian sandy soil on Loess Plateau, with undisturbed moss biocrusts serving as a control. The changes in respiration rate of moss biocrusts were monitored continuously, and its responses to different disturbance intensities were analyzed. The results showed that: 1) moderate disturbance stimulated moss biocrusts respiration, while heavy disturbance inhibited that. The respiration rate of moss biocrusts was increased by 41.1% and 22.2% at disturbance intensities of 10% and 30%, but was decreased by 8.9% and 15.3% at disturbance intensities of 50% and 70%, respectively. 2) The trampling disturbance significantly changed soil temperature but did not affect soil water content. In comparison to the control, soil temperature of biocrusts was decreased by 0.4 and 1.2 ℃ at disturbance intensities of 10% and 30%, but it was increased by 1.1 and 1.0 ℃ at disturbance intensities of 50% and 70%, respectively. 3) The respiration rate of moss biocrusts showed a significant exponential relationship with soil temperature and a linear positive relationship with soil water content under different disturbance intensities. However, the correlation between respiration rate of moss biocrust and the characteristics of moss biocrust was not significant. Soil temperature and water content could explain 70.6%-96.3% and 49.1%-70.0% of the total variation of respiration rate of moss biocrusts, respectively. In conclusion, grazing and trampling affected the respiration rate of moss biocrusts, with short-term moderate grazing and trampling would have positive effects. On the other hand, excessive grazing and trampling would reduce the rate of moss biocrust respiration. As a result, future studies on soil carbon balance of the Loess Plateau should consider the effects of grazing and trampling on biocrust respiration.放牧踩踏造成的土壤属性变化是引起土壤呼吸速率和碳固排波动的重要原因,但目前有关不同强度放牧踩踏对生物结皮呼吸的影响尚不明确。本研究针对黄土高原风沙土发育的藓结皮,以未干扰为对照,分别进行强度为10%、30%、50%和70%的模拟放牧踩踏干扰,连续测定了藓结皮呼吸速率的变化,分析了藓结皮呼吸速率对不同干扰强度的响应规律。结果表明: 1)适度干扰会激发藓结皮呼吸速率,而重度干扰则会抑制其呼吸速率。与未干扰相比,干扰10%和30%的藓结皮呼吸速率分别增加了41.1%和22.2%,而干扰50%和70%的藓结皮呼吸速率则分别降低了8.9%和15.3%。2)踩踏干扰显著改变了土壤温度,但对土壤含水量的影响不显著。与未干扰相比,干扰10%和30%的土壤温度分别显著降低了0.4和1.2 ℃,干扰50%和70%则分别显著增加了1.1和1.0 ℃。3)不同干扰强度下藓结皮呼吸速率与土壤温度和含水量分别呈显著指数和线性正相关关系,但与藓结皮基本特性无显著相关关系,土壤温度和水分可分别解释藓结皮呼吸速率动态变化的70.6%～96.3%和49.1%～70.0%。综上,放牧踩踏显著影响了藓结皮呼吸速率,短期适度放牧踩踏会激发藓结皮呼吸速率,而过度放牧踩踏则会抑制其呼吸速率。因此,在未来黄土高原地区土壤碳收支平衡研究中应考虑不同强度放牧踩踏对生物结皮呼吸的影响。.

The outcomes of coronavirus disease 2019 (COVID-19) vary between men and women. Some statistical reports have shown that men have a higher risk of developing COVID-19 and suffer from worse outcomes than females. Although there are many factors that can explain the high prevalence of COVID-19 in men, such as lifestyle habits and the different profile of comorbidities among sexes, the distinctions between male and female immune systems cannot be ignored. It has been sufficiently shown that sex differences have a critical influence on the shaping of immune response, which then leads to different pathogenesis in infectious diseases. Compared with males, females typically have a more effective innate and adaptive immune response to viral infections in COVID-19. What’s more, there is a growing body of evidence showing that estrogen exerts an effect on the regulation of immune response. This article examines the effect and mechanism of estrogen on COVID-19.

Proton exchange membrane fuel cells (PEMFCs) assembled with metal bipolar plates (BPPs) is a promising power source for new energy vehicles. However, metal BPPs have serious corrosion issues and the surface electrical performance degrades in the harsh PEMFC environment. Amorphous carbon (α-C) films exhibit improved properties with both high corrosion resistance and electrical conductivity. Subsequent vacuum heat treatment of the as-coated α-C films can change their phase composition and film structure, modifying their performance. This study prepared α-C films with a titanium interlayer on a SS316L substrate by DC balance magnetron sputtering and then subjected them to vacuum heat treatment at different temperatures (400–700 °C). These treated α-C films are systemically analyzed in terms of surface and cross-sectional morphologies, sp bond hybridization, interfacial electrical conductivity, and corrosion resistance. The results indicate that the conversion of sp3 to sp2 and the compact density of α-C films are greatly enhanced with an increase in temperature, greatly improving the corrosion resistance and surface conductivity of the films. These promising results lead to a potential direction for the post-coating treatment of α-C films on metal BPPs in PEMFCs.

Many biological materials have outstanding properties unparalleled by artificial materials because of their periodic and/or hierarchical structures. In this paper, the longitudinal elastic wave propagation in nacre-like materials with brick-and-mortar microstructures has been studied theoretically by taking the different deformation mechanisms into account. A viscoelastic model in relation to the sacrificial bond behavior for the organic matrix has been developed. The shear-lag model is adopted to simulate the deformation of the brick-mortar structure. Complex band structures have been analyzed and the mechanical model has been validated by finite element method. Results have shown that bandgaps with lower edge close to vanishing frequency may arise in such bio-inspired periodic structures and attenuated propagation of elastic waves may be dominant in the range of higher frequencies. It may cast light on the dynamic strengthening mechanisms in nacre-like materials and provide a scientific basis for the design of bio-inspired metamaterials with low-frequency bandgaps.

Mounting evidence has shown that exercise exerts extensive beneficial effects, including preventing and protecting against chronic diseases, through improving metabolism and other mechanisms. Recent studies have shown that exercise preconditioning affords significant cardioprotective effects. However, whether exercise preconditioning improves high fat diet (HFD)-induced obesity and lipid metabolic disorder remains unknown. The study was aimed to explore the effects of exercise preconditioning on HFD-induced obesity and lipid metabolic disorder in mice. 4-week-old C57BL/6 mice were subjected to swimming or sedentary control for 3 months, and then were fed with normal diet (ND) or HFD for 4 more months. The results showed that the blood glucose was decreased, and the glucose tolerance and grip strength were increased in exercised mice after training. Exercise preconditioning failed to improve HFD-induced body weight gain, but improved HFD-induced glucose intolerance. Exercise preconditioning showed no significant effects on both exercise capacity and physical activity in ND- and HFD-fed mice. HFD feeding increased total cholesterol and low density lipoprotein (LDL) levels in circulation, promoted subcutaneous fat and epididymal fat accumulation in mice. Exercise preconditioning increased circulating high density lipoprotein (HDL) and decreased circulating LDL, without affecting the subcutaneous fat and epididymal fat in HFD-fed mice. HFD feeding increased liver weight and hepatic total cholesterol contents, and dysregulated the expressions of several mitochondria function-related proteins in mice. These abnormalities were partially reversed by exercise preconditioning. Together, these results suggest that exercise preconditioning can partially reverse the HFD-induced lipid metabolic disorder and hepatic dysfunction, and these beneficial effects of exercise sustain for a period of time, even after exercise is discontinued.

Background: Simulation teaching, which cultivates cooperation and communication in the interprofessional team, has become a suitable type of interprofessional cooperation in college students' health professional courses. This study aimed to explore the intervention effect of simulated interprofessional education (SIPE) on clinical critical thinking of medical nursing students. Methods: This study was a mixed method research including quantitative and qualitative assessment. Results: A total of 30 medical nursing students were randomly divided into a control group (18) and an experimental group (12). The mean scores on interprofessional cooperation and critical thinking of the experimental group were higher than those of the control group (P < 0.05). Quantitative evaluation was conducted using a scale, and qualitative evaluation was conducted through semi-structured interviews. There were three themes emerged: clarifying team positioning, improving team effectiveness, and optimizing the learning experience. Conclusion: This study found that the SIPE program improved medical nursing students' ability to work in interprofessional teams.

Acoustic/elastic metasurfaces as a kind of two-dimensional metamaterials are of subwavelength thickness and show remarkable ability of acoustic/elastic wave manipulation. They have potential applications in various fields such as acoustic imaging, communications, cloaking, camouflage, vibration/noise control, energy harvesting, and nondestructive testing. In this review, we mainly summarize recent developments in acoustic/elastic phase gradient metasurfaces, including design principles, design of functional elements, wave field manipulation with applications, design of tunable metasurfaces, as well as the emerging digital coding metasurfaces. At last, we outline the future research directions in this field.

Background While single-method studies have reported on the effectiveness of simulated interprofessional teaching, our understanding of its full effects remains incomplete. Teaching design also provides no relevant theoretical guidance, which reduces the scientific quality and rigor of research. The purpose of this work was to study the effects of the simulated interprofessional education (SIPE) teaching model based on the 3P theory on the course of "Clinical Critical Thinking Training" through a convergent mixed method, and to provide the basis for future teaching design. Methods A convergent mixed-method design was used, which consisted of a survey and a semi-structured interview. Data collection took place from September 2021 to July 2022. A cluster sampling method was used to select 60 full-time nursing students from a school in China, and randomly divide them into a control group of 36 and an experimental group of 24. According to the principle of voluntary participation, 6 students majoring in clinical medicine and 6 students majoring in pharmacy were recruited to join the experimental group to form an interprofessional team. The students studied “Clinical Critical Thinking Training” together, in which the control group used traditional simulation teaching and the experimental group used SIPE. The CCTDI (California Critical Thinking Disposition Inventory) and AITCS-II Student (Assessment of Interprofessional Team Collaboration in Student Learning Scale) were used for quantitative evaluation before and after the course, and descriptive statistics and Mann–Whitney U test were used to compare the critical thinking and interprofessional collaboration skills of the two groups of students. Semi-structured interviews were used for qualitative evaluation. Thematic analysis was used to understand student development on the basis of inter-professional core competencies and learning experience. Results The students’ interprofessional cooperation abilities and critical thinking scores improved compared with the beginning of the course, but the scores of the experimental group were significantly higher than the control group (p Conclusion SIPE can build students' critical thinking, teamwork, and interprofessional core competencies, which makes it a useful teaching design.

This study was aimed to find out the effect of five light spectra (white, LDW; blue, LDB; green, LDG; red, LDR and yellow, LDY) on the visual development and growth performance of turbot (Scophthalmus maximus) larvae. The number (per 100 μm) of cone cells, outer nuclear cells, ganglion cells, the ratio of outer nuclear to cone and ganglion cells, lens diameter and the minimum separable angle were determined. Variations in growth performance in total length, body mass and body colour were also examined. The results showed that the LDB group underwent metamorphosis faster than did the other groups and attained the greatest total length, body mass and light sensitivity. The LDB group also completed the body colour variation prior to the other groups. The LDG group exhibited a high mortality rate since 25 dph (days post‐hatching). We arrived at the conclusions that the spectra could affect the vision and body development of turbot larvae specifically and the blue light had the enhancing efficiency during this process, followed by the white and yellow light. The red light imposed an inhibiting effect on these variations. Our study highlighted the significance of light condition and provided the reference for the farming.

The benefits of MPP delay optimization on hemodynamics and ventricular contraction synchronicity can be quantified with cardiac index (CI) and QRS width. A delay with the maximum CI and minimum QRS width may be the optimized settings for multipoint pacing (MPP).Twelve patients with advanced heart failure who received cardiac resynchronization therapy defibrillation with MPP at the Third People's Hospital of Chengdu from March 2016 to April 2019 were included. Interventricular and intraventricular delays were optimized through noninvasive cardiac output monitoring and a 12 lead ECG.According to CI, the optimized left ventricular- left ventricular - right ventricular delay setting was mainly 25 ms-25 ms and 40 ms-40 ms. And the delay with the minimum QRS width was mainly in 5 ms-5 ms, 25 ms-25 ms, and 40 ms-25 ms. The optimal MPP configuration increased CI compared to the MPP setting that produced the minimum CI (4.5 ± 1.3 vs. 2.8 ± 1.0 L/min/m2, P 0.001). The QRS width of the optimized MPP was narrower than the MPP setting that produced the maximum QRS width (127 ± 20 vs. 160 ± 29 ms, P 0.001).Delay optimization improves hemodynamic response and ventricular contraction synchronicity. The delay of 25 ms-25 ms may be the optimal setting for most MPP patients.

The increase of neutron flux in pulsed spallation neutron facilities imposes demands on the neutron detector for beam monitoring, including excellent neutron/gamma discrimination, wide dynamic neutron-flux measurement range, wavelength resolution, and long-term stability. In this paper, we developed a ceramic GEM-based (gas electron multiplier) neutron detector with an active area of 100 mm × 100 mm. It adopted a thinner conversion material and the stopping layer to lower the detection efficiency so as to extend the dynamic measurement range of the detector. The detection efficiency of this detector was investigated by the Monte Carlo (MC) tool FLUKA, showing that the low efficiency around 0.01% for 1 Åneutrons was reached by using a 0.1 μm natB4C converter appended with an aluminum film of 2 μm thickness. Its validation of the wavelength spectra measurement was verified by comparisons with that made with an LND monitor, and it could work at the condition of 7.1 × 109 n/s for 2.5 Åneutrons. In addition, it was demonstrated that this detector was able to measure the beam profile with a position resolution of better than 2.1 ± 0.1 mm. The results of simulations and experiments show that this ceramic-GEM neutron detector can meet the requirements of the direct measurement of high-flux beam, and it will be a new neutron detector for the beam monitoring at the China spallation neutron source (CSNS).

In last two decades, it has been theoretically and experimentally demonstrated that seismic metamaterials are capable of isolating seismic surface waves. Inertial amplification mechanisms with small mass have been proposed to design metamaterials to isolate elastic waves in rods, beams, and plates at low frequencies. In this Letter, we propose an alternative type of seismic metamaterial providing an ultra-low-frequency bandgap induced by inertial amplification. A unique kind of inertially amplified metamaterial is first conceived and designed. Its bandgap characteristics for flexural waves are then numerically and experimentally demonstrated. Finally, the embedded inertial amplification mechanism is introduced on a soil substrate to design a seismic metamaterial capable of strongly attenuating seismic surface waves around a frequency of 4 Hz. This work provides a promising alternative way to conceive seismic metamaterials to steer and control surface waves.

An experimental researches was performed for carbon black-reinforced cement-matrix composites. The carbon black used was in the form of particles with a nano-size. Results show that when content of the carbon black is between 0.25% and 0.75% by weight of cement, both flexural and compressive strengths of the composite can be enhanced. Flexural strength increases up to 9.69%, and compressive strength increases up to 6.92%, respectively. Moreover, the carbon black-reinforced composite is of high strain-sensing ability. The fractional change in resistance () increases monotonically upon compressive loading, and decreases monotonically upon unloading. These properties indicate that the carbon black-reinforced composite can be used for structural function, while at the same time act as a strain sensor itself. Compared with carbon fiber-reinforced composites, the carbon black-reinforced composite has a low price and is easy for mixing.

Purpose In this era of life highly comminuted and multi planar tibial plateau fractures involving the posterior corners are more commonly seen and addressed in the literature than before. Among these several types have not been described in the currently used classification systems. In fact simple classification systems ignore several fracture types and leniently grouped the fractures with different mechanism, morphology, treatment modalities and prognosis in same category. On the other hand, more extensive nature classifications with detailed subdivisions are difficult to remember for clinicians. The clinical reliability of these classifications is another problem. All these issues demand the potential need of a new classification. The aim of this study was to describe a quadrant specific two column classification of tibial plateau fractures and to analyse its inter-observer and intra-observer reliability, clinical assessment and application. Materials and methods From January 2009 to December 2015, 44 patients with tibial plateau fractures were studied retrospectively. The antero-posterior (AP), lateral X-rays and computed tomography (CT) with axial transverse, sagittal, coronal and three dimensional (3D) reconstruction images were performed for all the patients. All of the fractures were categorized according to quadrant specific two column classification and the traditional Schatzker’s classification. The comparative analysis for inter-observer and intra-observer reliability of the new classification and the Schatzker’s classification was conducted by four observers. Results Three cases didn’t match any type in the Schatzker’s classification. While on the other hand, all cases were classified by two column classification. The mean kappa values for inter-observer reliability by using the Schatzker’s classification was 0.723 (range, 0.674-0.823), representing substantial agreement, whereas the mean kappa value was 0.939 (range: 0.897-0.974), representing almost perfect agreement according to two column classification. The mean kappa values for intra-observer reliability using the Schatzker’s classification and two column classification were 0.789 (range: 0.590-0.864) and 0.955 (range:0.923-0.948) showing substantial agreement and almost perfect agreement. Conclusion The quadrant specific two column classification is anatomically oriented, CT based and clinically valid. The different fracture types according to anatomic location are represented alphanumerically so that treatment matched to specific fracture type (quadrant specific anatomic fixation) for optimal outcomes. Furthermore, it demonstrates higher inter-observer and intra-observer reliability. This classification can be adopted to strengthen the traditional Schatzker’s classification, particularly in the multi planar and posteriorly extended plateau fractures. It can be used as a reliable research tool. The database can be used to distinguish different fracture types, individual type incidences, specific treatment and also prognosis. Authors suggest a large multi-centre study.

This paper investigates the robust H∞ fault detection problem for networked control systems with Markov time-delays and data packet loss in both S/C and C/A channels. First, the time-delay from sensor to controller (S/C) and the time-delay from sensor to actuator (C/A) are described by two different Markov chains. Two random variables obeying the Bernoulli distribution are used to describe the packet loss between the sensor and the controller together between the controller and the actuator. Based on this, a fault detection filter is constructed and the closed-loop system mathematical model is established. Then, the solution method of the fault detection filter and controller gain matrix is given. The relationship between the probability of successful packet transmission and the ability to suppress external disturbance is obtained. Finally, simulation verifies the effectiveness of the proposed method.

A paraffin-dominated battery thermal management system (BTMS) is developed in this work, to protect the Li-ion battery (LIB) module from thermal runaway and improve the output performance of autonomous underwater vehicles (AUVs). First, a physical model is established for analyzing the transient heat transfer process and corresponding thermal behavior, occurring in the AUV’s battery module during its charge/discharge cycles. Second, numerical calculations are performed by using a pressure-velocity coupled algorithm based on a finite volume solver, to reveal heat dissipation and temperature distribution on the battery module cooled by the paraffin-dominated BTMS. Third, the calculation results are verified comparing with the open literature data. It indicates that air-dependent thermal resistance in the battery module causes an inevitable temperature rise and nonuniformity accounting for potential thermal runaway. Also, the customized RT48 paraffin mixture with a melting temperature range from 321.0 K to 325.0 K is high-efficiency to maintain the optimal working temperature and temperature difference for the battery module. In conclusion, a well-controlled phase change temperature range and equivalent thermal conductivity combined with the optimized charge/discharge strategy is exceedingly crucial for guaranteeing thermal safety and high performance regarding the AUVs. Besides, the research findings are in good agreement with the open literature data.

We investigate experimentally Lamb wave propagation in coupled-resonator elastic waveguides (CREWs) formed by a chain of cavities in a two-dimensional phononic crystal slab with cross holes. Wide complete bandgaps, extending from 53 to 88 kHz, are first measured in a finite phononic crystal slab sample. A straight waveguide and a wave splitting circuit with 90° bends are then designed, fabricated and measured. Elastic Lamb waves are excited by a piezoelectric patch attached to one side of the phononic slab and detected using a scanning vibrometer. Strongly confined guiding and splitting at waveguide junctions are clearly observed for several guided waves. Numerical simulations are found to be in excellent agreement with experimental results and allow for the identification of the involved resonant cavity modes. The influence on the dispersion of guided waves of the slab thickness and of the hole length is also investigated. The results have implications for the design of innovative phononic devices with strong confinement and tailorable dispersion.

Waveguiding in a phononic crystal (PC) can be achieved along either linear line defects or a sequence of cavities, for frequencies belonging to a complete bandgap. When waves are coupled inside a PC waveguide, modulations in the frequency transmission are generally observed, leading to the formation of a channeled spectrum. We show that the channeled spectrum results from the interference of forward and backward guided Bloch waves. We first theoretically develop a Bloch wave interference model. Then, we consider the case of linear waveguides and of coupled-resonator waveguides formed in a 2D square PC composed of water cylinders in mercury. The transmission properties of waveguides with different length and defect distribution are examined. In all cases, the observed channeled spectra are well explained by the theoretical model. This work is relevant to the design of new acoustic and elastic wave devices.

High-performance and lightweight waterborne acoustic devices have provided important support for the development of ocean exploration, health monitoring, etc. In this work, we propose a high-efficiency ultrathin nonlocal waterborne acoustic metasurface. Due to strong nonlocal interaction between the waterborne unit cells induced by the fluid-solid interaction, a nonlocal design concept based on diffraction theory and the optimization approach is proposed to design waterborne acoustic metasurfaces, in contrast to the local design based on the generalized Snell's law. The theoretical efficiency limitation of the generalized Snell's law can be broken, and unitary efficiency could be obtained even for large-angle anomalous reflection. The high-efficiency modulation is achieved owing to the energy flow along the metasurface resulting from the nonlocal interaction. The thickness of the waterborne acoustic metasurface can be minimized to one tenth or even one sixtieth of the working wavelength. The nonlocal design with fluid-solid interaction paves the way for high-efficiency and deep-subwavelength waterborne acoustic wave manipulation.

Acoustic metasurface carpet cloak has suffered from narrowband limitation due to highly frequency-dependent phase response. Here, we adopt two entirely different ways to broaden the working frequency range of the carpet cloak with dynamic or static metasurface structure. Numerical simulations and experimental measurements demonstrate that the designed dynamic or static metasurface carpet cloak can both exhibit a broadband stealth performance. The proposed design strategy is expected to break the narrowband limitation of metasurfaces, making a significant difference to the practical applications of the broadband acoustic devices.

The solution processed method has been wildly used in the thin film fabrication because of the advantages of low cost, high efficiency, large scale for production, and long-term stability. In this paper, a normally-off hydrogen-terminated diamond field-effect transistor (FET) has been realized by using a solution processed SnO2 (sp-SnO2) film as an insulator layer. X-ray photoelectron spectroscopy results demonstrated the stoichiometry of the sp-SnO2 film, which shows good insulator properties with leakage current density less than 2.1 × 10−5 A·cm−2 at gate voltages from −6.0 to 6.0 V. The drain–source current maximum, threshold voltage, extrinsic transconductance maximum, and effective mobility of the FET with a gate length of 10 μm are −17.6 mA·mm−1, −0.5 V, 5.7 mS·mm−1, and 41.3 cm2/V s, respectively. According to the capacitance voltage characteristic, the enhancement mode could be ascribed to the high positive fixed charge density in the sp-SnO2 film, which will repel the hole in the channel. This paper provides a simple method and a low temperature process to fabricate an insulator layer.

We investigate two-dimensional phononic metaplates consisting of a periodic array of cups on a thin epoxy plate that is perforated with periodic cross holes. The cups are individually filled with water or remain empty, in view of creating reconfigurable phononic waveguides. Phononic band gaps exist for empty or filled epoxy cups, leading to waveguides defined with either positive or negative contrast. Straight and 90° bent waveguides are considered experimentally. Lamb waves are excited by a piezoelectric patch glued onto the metaplate and are imaged using a scanning laser vibrometer. Experimental results are compared to a three-dimensional finite element model of fluid–structure interaction. Passing and forbidden frequency ranges are identified for positive and negative contrast, and confined propagation is observed along the waveguides. Significantly, the propagation of acoustoelastic waves in the 90° bent waveguides is observed experimentally. Reconfigurability and reusability are thus realized based on the coupling of elastic waves in the solid and acoustic waves in the fluid. The results show plenty of potentiality for the practical design of multiplexed and programmable acoustic devices implemented with reconfigurable waveguides printed on demand in a phononic metaplate.

Different fixation modalities are available for fixation of posterior malleolar fractures (PMFs), but the best method is still unclear. The purpose of this study was to carry out a comparative biomechanical analysis of three commonly used fixation constructs for PMFs using experimental and finite element analysis (FEA). 15 human cadaveric ankle specimens were randomly divided into three groups. Specimens in group-A were fixed with two anteroposterior (AP) lag screws, group-B with two posteroanterior (PA) lag screws, and for group-C, a posterior plate was used. Each model was subjected to axial load. Outcomes included loads for 0.5 mm, 1 mm, 1.5 mm, and 2 mm vertical displacements of posterior fragments were noted. 3D FE models were reconstructed from computed tomography (CT) images and subjected to vertical loads. The model’s stress, fracture step-off, and resultant strains in implants were also studied in 3D FE models. Significantly higher amounts of mean compressive loads were observed to cause the same amount of vertical displacements in plate group (265 ± 60.21 N, 796 ± 57.27 N, 901.18 ± 8.88 N, 977.26 ± 13.04 N) than AP (102.7 ± 16.78 N, 169.5 ± 19.91 N, 225.32 ± 15.92 N, 269.32 ± 17.29 N) and PA (199.88 ± 31.43 N, 362.80 ± 28.46 N, 431.3 ± 28.12 N, 541.86 ± 36.05 N) lag screws respectively (P

We study experimentally a chain of defect resonators in a phononic crystal slab and observe its collective resonances at ultrasonic frequencies of a few megahertz. A phononic crystal of cross holes is fabricated in a thin fused-silica plate by femtosecond-laser writing followed by $\mathrm{KOH}$ etching. A chain of 17 coupled resonators is defined with no definite spatial periodicity but similar coupling strength between nearest-neighbor resonators. The full phononic band gap ensures that only evanescent waves in the crystal can tunnel between adjacent resonators in the plane. The resulting evanescent-coupling strength decreases exponentially with distance. Collective resonances are excited by a frequency-driven piezoelectric vibrator attached at one end of the chain and imaged along the chain with a laser Doppler vibrometer. A discrete spectrum of resonances is observed and explained by a model representing the chain as a phononic polymer. The theoretical analysis is supported by finite-element simulations that agree well with experimental results. Chains of evanescently coupled microresonators forming phononic polymers could find applications in ultrasonic sensing, for implementation in topological phononics, and for the design of optomechanical resonator chains.