Mechanism of airborne sound absorption through triboelectric effect for noise mitigation.

Mitigating broadband noise with passive airborne sound absorbers has been a long-lasting challenge, particularly for low-frequency anthropogenic sounds below kilohertz with long wavelengths, which require bulky materials for effective absorption. Here, we propose a strategy that utilizes local triboelectric effect and in-situ electrical energy dissipation mechanism for airborne sound absorption. This approach involves a fundamentally different mechanism that converts airborne sound into electricity for energy dissipation, in contrast to conventional mechano-thermal energy conversion mechanisms. We establish an equivalent acoustic impedance model to provide theoretical analysis of the underlying sound absorption mechanisms, with a theoretical maximum mechano-electro-thermal coupling efficiency approaching 100% under optimal conditions. We design fibrous triboelectric composite foam materials accordingly and show their substantially boosted acoustic absorption performance experimentally, where the adoption of diverse triboelectric material pairs validates that a larger difference in material charge affinities intensifies the local triboelectric effect and results in higher acoustic absorbing performance.

Analysis and Guideline for Determining Piezoelectric Coefficient for Films With Substrate Constraint.

Piezoelectric films including coatings are widely employed in various electromechanical devices. Precise measurement for piezoelectric film properties is crucial for both piezoelectric material development and design of the piezoelectric devices. However, substrate constraint on the deformation of piezoelectric films could cause significant impacts on the reliability and accuracy of the piezoelectric coefficient measurement. Through both theoretical finite element analysis (FEA) and experimental validation, here we have identified three important factors that strongly affect the measurement results: ratio of Young's modulus of substrate to piezoelectric film, ratio of electrode size to substrate thickness, and test frequency. Our investigations show that a relatively smaller substrate's Young's modulus to film, and a larger ratio of electrode size to substrate thickness would cause a larger substrate bending effect and thus potentially more significant measurement errors. Moreover, intense transversal displacement fluctuation can be excited at excessively high frequencies, leading to unreliable measurements. Various well-established piezoelectric measurement methods are compared with outstanding measurement issues identified for those commonly used piezoelectric films and substrates. We further establish the guidelines for piezoelectric coefficient measurements to achieve high reliability and accuracy, thus important to the wide technical community with interests in electromechanical active materials and devices.

Expression of cancer susceptibility candidate 11 in ovarian cancer tissues and its role in doxorubicin resistance.

We aimed to investigate the expression of cancer susceptibility candidate 11 (CASC11) in ovarian cancer (OC) tissues and its role in doxorubicin (Dox) resistance. A total of 98 patients were included as subjects. Reverse transcription-polymerase chain reaction was employed to determine the expressions of CASC11 in OC and para-OC tissues, and in OC cells (A2780, SKOV3, OVCAR3 and A547) and human normal ovarian epithelial cells (IOSE-80) from these patients. OC SKOV3/R cell line with Dox resistance was established and transfected with small interfering (si)-CASC11 to down-regulate CASC11 expression. Based on the constructed nude mouse model of orthotopic transplanted tumor, the growth curves were plotted, and the changes in tumor volume and apoptosis were observed by hematoxylin-eosin staining. OC tissues had a significantly higher mRNA expression of CASC11 than that of para-OC tissues (P < 0.05). A547, OVCAR3, A2780 and SKOV3 cells had significantly higher mRNA expressions of CASC11 than that of IOSE-80 cells (P < 0.05). The transplanted tumor was significantly smaller in volume in the si-CASC11 group than that in the si-normal control (NC) group from the 8th days after transplanted tumor inoculation (P < 0.05). The tumor growth inhibition rate significantly rose in the si-CASC11 group in comparison with that in the si-NC group (P < 0.05). CASC11 has high expression in OC tissues. Knockout of CASC11 weakens the proliferative, invasive and migratory potentials and enhances the apoptotic potential of Dox-resistant OC cells, thereby reversing their Dox resistance.

Explore Ultrasonic-Induced Mechanoluminescent Solutions towards Realising Remote Structural Health Monitoring.

Ultrasonic guided waves, which are often generated and detected by piezoelectric transducers, are well established to monitor engineering structures. Wireless solutions are sought to eliminate cumbersome wire installation. This work proposes a method for remote ultrasonic-based structural health monitoring (SHM) using mechanoluminescence (ML). Propagating guided waves transmitted by a piezoelectric transducer attached to a structure induce elastic deformation that can be captured by elastico-ML. An ML coating composed of copper-doped zinc sulfide (ZnS:Cu) particles embedded in PVDF on a thin aluminium plate can be used to achieve the elastico-ML for the remote sensing of propagating guided waves. The simulation and experimental results indicated that a very high voltage would be required to reach the threshold pressure applied to the ML particles, which is about 1.5 MPa for ZnS particles. The high voltage was estimated to be 214 Vpp for surface waves and 750 Vpp for Lamb waves for the studied configuration. Several possible technical solutions are suggested for achieving ultrasonic-induced ML for future remote SHM systems.

Thermoelectric coupling effect in BNT-BZT-xGaN pyroelectric ceramics for low-grade temperature-driven energy harvesting.

Pyroelectric energy harvesting has received increasing attention due to its ability to convert low-grade waste heat into electricity. However, the low output energy density driven by low-grade temperature limits its practical applications. Here, we show a high-performance hybrid BNT-BZT-xGaN thermal energy harvesting system with environmentally friendly lead-free BNT-BZT pyroelectric matrix and high thermal conductivity GaN as dopant. The theoretical analysis of BNT-BZT and BNT-BZT-xGaN with x = 0.1 wt% suggests that the introduction of GaN facilitates the resonance vibration between Ga and Ti, O atoms, which not only contributes to the enhancement of the lattice heat conduction, but also improves the vibration of TiO6 octahedra, resulting in simultaneous improvement of thermal conductivity and pyroelectric coefficient. Therefore, a thermoelectric coupling enhanced energy harvesting density of 80 µJ cm-3 has been achieved in BNT-BZT-xGaN ceramics with x = 0.1 wt% driven by a temperature variation of 2 oC, at the optical load resistance of 600 MΩ.

Large Electromechanical Response in a Polycrystalline Alkali-Deficient (K,Na)NbO3 Thin Film on Silicon.

The demand for large electromechanical performance in lead-free polycrystalline piezoelectric thin films is driven by the need for compact, high-performance microelectromechanical systems (MEMS) based devices operating at low voltages. Here we significantly enhance the electromechanical response in a polycrystalline lead-free oxide thin film by utilizing lattice-defect-induced structural inhomogeneities. Unlike prior observations in mismatched epitaxial films with limited low-frequency enhancements, we achieve large electromechanical strain in a polycrystalline (K,Na)NbO3 film integrated on silicon. This is achieved by inducing self-assembled Nb-rich planar faults with a nonstoichiometric composition. The film exhibits an effective piezoelectric coefficient of 565 pm V-1 at 1 kHz, surpassing those of lead-based counterparts. Notably, lattice defect growth is substrate-independent, and the large electromechanical response is extended to even higher frequencies in a polycrystalline film. Improved properties arise from unique lattice defect morphology and frequency-dependent relaxation behavior, offering a new route to remarkable electromechanical response in polycrystalline thin films.

A multiscale generative model to understand disorder in domain boundaries.

A continuing challenge in atomic resolution microscopy is to identify significant structural motifs and their assembly rules in synthesized materials with limited observations. Here, we propose and validate a simple and effective hybrid generative model capable of predicting unseen domain boundaries in a potassium sodium niobate thin film from only a small number of observations, without expensive first-principles calculations or atomistic simulations of domain growth. Our results demonstrate that complicated domain boundary structures spanning 1 to 100 nanometers can arise from simple interpretable local rules played out probabilistically. We also found previously unobserved, significant, tileable boundary motifs that may affect the piezoelectric response of the material system, and evidence that our system creates domain boundaries with the highest configurational entropy. More broadly, our work shows that simple yet interpretable machine learning models could pave the way to describe and understand the nature and origin of disorder in complex materials, therefore improving functional materials design.

Association between polycystic ovary syndrome and risk of non-alcoholic fatty liver disease: a meta-analysis.

INTRODUCTION: There have been many studies assessing whether abnormal metabolic and hormone levels among women with polycystic ovary syndrome (PCOS) are associated with a greater risk of non-alcoholic fatty liver disease (NAFLD). However, previous studies repported no consistent outcomes. To provide a comprehensive evaluation regarding the role of PCOS in the risk of NAFLD, we updated the published literature and conducted this systemic review and meta-analysis. MATERIAL AND METHODS: Electronic databases (Web of Science and PubMed) were searched for literature up to October 2022. We used STATA 12.0 software to compute odds ratios (ORs) and 95% confidence intervals (CIs), to evaluate the association between PCOS and risk of NAFLD. RESULTS: The study indicated that PCOS was significantly related to an elevated risk of NAFLD (OR = 2.93, 95% CI 2.38 to 3.62, I2 = 83.7%, p < 0.001). Meta-regression analysis showed that age and body mass index (BMI) were not responsible for heterogeneity across the studies (age: p = 0.096; BMI: p = 0.418). Sensitivity analysis indicated no alteration in the direction of effect when any study was eliminated. Begg's test, Egger's test, Begg's test, and funnel plot indicated a significant risk of publication bias (Egger's test: p = 0.028; Begg's test: p < 0.001). CONCLUSION: This meta-analysis reported that PCOS was associated with an elevated risk of NAFLD. Early proper detection of NAFLD for PCOS women is essential. All patients with PCOS should undergo appropriate diagnostics for early detection of fatty liver and fibrosis.

Transvaginal small bowel evisceration after cervical loop electrosurgical excision procedure: a case report.

Transvaginal small bowel evisceration is a life-threatening condition, which is usually seen in postmenopausal women with a history of gynecological surgery. Cervical loop electrosurgical excision procedure (LEEP) is widely used in the treatment of cervical intraepithelial neoplasia (CIN), and its surgical risk and postoperative complications are relatively low because of the simplicity of the operation. However, improper operation may result in perforation of the uterus, which can cause prolapse of the small bowel into the vagina. We here reported an extremely rare case of a young woman with transvaginal small bowel evisceration after cervical LEEP, achieving a good prognosis after the prolapsed bowel was reduced. The patient underwent cervical LEEP as a treatment for CIN III, but the LEEP resulted in a laceration of about 4.0 cm × 3.5 cm on the peritoneum of the uterovesical peritoneal reflection and a laceration of about 2.0 cm × 1.5 cm on the anterior wall of the cervical canal. Through the two lacerations, the pelvic cavity is connected to the vagina and the small intestine prolapsed into the vagina. Due to aggressive surgical intervention, the patient achieved a favorable prognosis after successfully reducing the prolapsed bowel.

Environmental Robustness and Resilience of Direct-Write Ultrasonic Transducers Made from P(VDF-TrFE) Piezoelectric Coating.

Conformability, lightweight, consistency and low cost due to batch fabrication in situ on host structures are the attractive advantages of ultrasonic transducers made of piezoelectric polymer coatings for structural health monitoring (SHM). However, knowledge about the environmental impacts of piezoelectric polymer ultrasonic transducers is lacking, limiting their widespread use for SHM in industries. The purpose of this work is to evaluate whether direct-write transducers (DWTs) fabricated from piezoelectric polymer coatings can withstand various natural environmental impacts. The ultrasonic signals of the DWTs and properties of the piezoelectric polymer coatings fabricated in situ on the test coupons were evaluated during and after exposure to various environmental conditions, including high and low temperatures, icing, rain, humidity, and the salt fog test. Our experimental results and analyses showed that it is promising for the DWTs made of piezoelectric P(VDF-TrFE) polymer coating with an appropriate protective layer to pass various operational conditions according to US standards.

Surface Crack Monitoring by Rayleigh Waves with a Piezoelectric-Polymer-Film Ultrasonic Transducer Array.

This paper presents a method for measuring surface cracks based on the analysis of Rayleigh waves in the frequency domain. The Rayleigh waves were detected by a Rayleigh wave receiver array made of a piezoelectric polyvinylidene fluoride (PVDF) film and enhanced by a delay-and-sum algorithm. This method employs the determined reflection factors of Rayleigh waves scattered at a surface fatigue crack to calculate the crack depth. In the frequency domain, the inverse scattering problem is solved by comparing the reflection factor of the Rayleigh waves between the measured and the theoretical curves. The experimental measurement results quantitatively matched the simulated surface crack depths. The advantages of using the low-profile Rayleigh wave receiver array made of a PVDF film for detecting the incident and reflected Rayleigh waves were analyzed in contrast with those of a Rayleigh wave receiver using a laser vibrometer and a conventional lead zirconate titanate (PZT) array. It was found that the Rayleigh waves propagating across the Rayleigh wave receiver array made of the PVDF film had a lower attenuation rate of 0.15 dB/mm compared to that of 0.30 dB/mm of the PZT array. Multiple Rayleigh wave receiver arrays made of the PVDF film were applied for monitoring surface fatigue crack initiation and propagation at welded joints under cyclic mechanical loading. Cracks with a depth range of 0.36-0.94 mm were successfully monitored.

Diverse Defects in Alkali Niobate Thin Films: Understanding at Atomic Scales and Their Implications on Properties.

Defects in ferroelectric materials have many implications on the material properties which, in most cases, are detrimental. However, engineering these defects can also create opportunities for property enhancement as well as for tailoring novel functionalities. To purposely manipulate these defects, a thorough knowledge of their spatial atomic arrangement, as well as elastic and electrostatic interactions with the surrounding lattice, is highly crucial. In this work, analytical scanning transmission electron microscopy (STEM) is used to reveal a diverse range of multidimensional crystalline defects (point, line, planar, and secondary phase) in (K,Na)NbO3 (KNN) ferroelectric thin films. The atomic-scale analyses of the defect-lattice interactions suggest strong elastic and electrostatic couplings which vary among the individual defects and correspondingly affect the electric polarization. In particular, the observed polarization orientations are correlated with lattice relaxations as well as strain gradients and can strongly impact the properties of the ferroelectric films. The knowledge and understanding obtained in this study open a new avenue for the improvement of properties as well as the discovery of defect-based functionalities in alkali niobate thin films.

[Review and prospect of traditional Chinese medicine in treatment of hypertension].

Hypertension, a primary cause of cardiovascular and cerebrovascular events, has become a major global public health problem and caused a heavy burden of health economics on the society. In "the 20 Most Important and Most Preventable Health Problems" released by the Chinese Academy of Engineering, hypertension was ranked the second. Due to the disease complexity, many hypertension patients need to take antihypertensive drugs for life. Although significant progress has been achieved in blood pressure lowering by western medicines, the problems including adverse reactions, poor compliance due to long-term medication, and ineffective mitigation in clinical symptoms related to hypertension remain to be addressed. In the last decade, the research on traditional Chinese medicine(TCM) treatment of hypertension has received much attention and achieved remarkable progress. The TCM treatment of hypertension is the most active area of research with integrated Chinese and western medicine in China. In addition to lowering blood pressure smoothly, TCM can alleviate clinical symptoms, reverse risk factors, improve the quality of life, and protect target organs from the damage caused by hypertension. This article systematically reviews the research progress of TCM in treating hypertension in the last decade from the following four aspects: consensus on guideline, clinical trial, experimental study, and systematic review/Meta-analysis. It summarized the evidence of TCM in reducing blood pressure and clarified the mechanism of TCM in reducing blood pressure, aiming to provide a reference for the TCM diagnosis and treatment of hypertension and the development of new drugs.

Sound Absorption Improvement in Porous Ferroelectret Polyethylene with Effective Piezoelectric Mechanism.

Airborne sound absorption in porous materials involves complex mechanisms of converting mechanical acoustic energy into heat. In this work, the effective piezoelectric properties of polyethylene ferroelectret foams on sound absorption were investigated by comparable samples with and without the piezoelectric response. Corona poling and thermal annealing treatments were applied to the samples in order to enable and remove the piezoelectric property, respectively, while the microstructure and the mechanical properties remained substantially unchanged. The effective piezoelectric properties and airborne sound absorption coefficients of the polyethylene foam samples before and after material treatments were measured and analyzed. Our experimental results and theoretical analysis showed that the open-cell ferroelectret polymer foam with an effective piezoelectric property provides an additional electromechanical energy conversion mechanism to enhance the airborne acoustic absorption performance.

Deciphering the atomic-scale structural origin for large dynamic electromechanical response in lead-free Bi0.5Na0.5TiO3-based relaxor ferroelectrics.

Despite the extraordinary electromechanical properties of relaxor ferroelectrics, correlating their properties to underlying atomic-scale structures remains a decisive challenge for these "mess" systems. Here, taking the lead-free relaxor ferroelectric Bi0.5Na0.5TiO3-based system as an example, we decipher the atomic-scale structure and its relationship to the polar structure evolution and large dynamic electromechanical response, using the direct atomic-scale point-by-point correlation analysis. With judicious chemical modification, we demonstrate the increased defect concentration is the main driving force for deviating polarizations with high-angle walls, leading to the increased random field. Meanwhile, the main driving force for deviating polarizations with low-angle walls changes from the anti-phase oxygen octahedral tilting to the multidirectional A-O displacement, leading to the decreased anisotropy field. Benefiting from the competitive and synergetic equilibrium of anisotropic field versus random field, the facilitated polarization rotation and extension versus facilitated domain switching are identified to be responsible for the giant electromechanical response. These observations lay a foundation for understanding the "composition-structure-property" relationships in relaxor ferroelectric systems, guiding the design of functional materials for electromechanical applications.

Bond engineering of molecular ferroelectrics renders soft and high-performance piezoelectric energy harvesting materials.

Piezoelectric materials convert mechanical stress to electrical energy and thus are widely used in energy harvesting and wearable devices. However, in the piezoelectric family, there are two pairs of properties that improving one of them will generally compromises the other, which limits their applications. The first pair is piezoelectric strain and voltage constant, and the second is piezoelectric performance and mechanical softness. Here, we report a molecular bond weakening strategy to mitigate these issues in organic-inorganic hybrid piezoelectrics. By introduction of large-size halide elements, the metal-halide bonds can be effectively weakened, leading to a softening effect on bond strength and reduction in polarization switching barrier. The obtained solid solution C6H5N(CH3)3CdBr2Cl0.75I0.25 exhibits excellent piezoelectric constants (d33 = 367 pm/V, g33 = 3595 × 10-3 Vm/N), energy harvesting property (power density is 11 W/m2), and superior mechanical softness (0.8 GPa), promising this hybrid as high-performance soft piezoelectrics.

Active Ultrasonic Structural Health Monitoring Enabled by Piezoelectric Direct-Write Transducers and Edge Computing Process.

While the active ultrasonic method is an attractive structural health monitoring (SHM) technology, many practical issues such as weight of transducers and cables, energy consumption, reliability and cost of implementation are restraining its application. To overcome these challenges, an active ultrasonic SHM technology enabled by a direct-write transducer (DWT) array and edge computing process is proposed in this work. The operation feasibility of the monitoring function is demonstrated with Lamb wave excited and detected by a linear DWT array fabricated in situ from piezoelectric P(VDF-TrFE) polymer coating on an aluminum alloy plate with a simulated defect. The DWT array features lightweight, small profile, high conformability, and implementation scalability, whilst the edge-computing circuit dedicatedly designed for the active ultrasonic SHM is able to perform signal processing at the sensor nodes before wirelessly transmitting the data to a remote host device. The successful implementation of edge-computing processes is able to greatly decrease the amount of data to be transferred by 331 times and decrease the total energy consumption for the wireless module by 224 times. The results and analyses show that the combination of the piezoelectric DWT and edge-computing process provides a promising technical solution for realizing practical wireless active ultrasonic SHM system.

Association Between Metformin Use and the Risk, Prognosis of Gynecologic Cancer.

Background: For gynecological cancer patients, the beneficial effect of metformin use remains controversial due to inconsistent results of published articles. By conducting a meta-analysis, we aimed to evaluate the effect of metformin in reducing the risk and improving the survival of gynecological cancer among women with diabetes mellitus (DM). Methods: Articles exploring association between metformin use and the risk, as well as prognosis of gynecologic cancer in DM, were searched in the databases: PubMed, Web of Science, SCOPUS, EMBASE, EBSCO, and PROQUEST. Articles were published before May 2022. All the studies were conducted using STATA 12.0 software. Results: The meta-analysis showed no significant association between metformin use and risk of gynecologic cancer in DM with a random effects model [odds ratio (ORs)/relative risk (RR) = 0.91, 95% confidence intervals (CI) 0.77 to 1.08, I2 = 84.2%, p < 0.001]. Metformin use was associated with reduced overall survival (OS) and progression-free survival (PFS) of gynecologic cancer in DM with random effects models [OS: hazard ratio (HR) = 0.60, 95% CI 0.49-0.74, I2 = 55.2%, p = 0.002; PFS: HR = 0.55, 95% CI 0.33-0.91, I2 = 69.1%, p = 0.006], whereas no significant association was showed between metformin use and recurrence-free survival (RFS), as well as cancer-specific survival (CSS) of gynecologic cancer in DM with random effects models (RFS: HR = 0.60, 95% CI 0.30-1.18, I2 = 73.7%, p = 0.010; CSS: HR = 0.78, 95% CI 0.43-1.41, I2 = 72.4%, p = 0.013). Conclusions: In conclusion, this meta-analysis indicated that metformin may be a useful adjuvant agent for gynecological cancer with DM, especially for patients with ovarian cancer and endometrial cancer.