To address long-range missions, flight endurance, primarily constrained by fuel consumption rate, has become a crucial performance metric for advanced aircraft. Conventionally, substantial ram air is used for cooling the hot fuel return (HFR) in the fuel thermal management system (FTMS), leading to excessive fuel consumption due to ram air drag, which necessitates further optimization. This paper investigates the impact of ram air reduction on both fuel supply and thermal management capabilities of the FTMS. It is found that when the thermal management flow path (TMFP) maintains in the full recirculation state (FRS), reducing ram air flow conserves not only fuel but also fuel heat sink, benefiting the mitigation of both fuel depletion and thermal failure. Calculation results indicate that flight endurance is extended by 1

With the increasing demand for super-maneuverability and fast response capability of modern military aircraft, aero-engines must adapt to rapidly changing operating conditions in a short time. During processes of rapid acceleration, deceleration, and sudden changes in operating conditions, the transient characteristics of the engine are key factors influencing the aircraft's maneuverability and combat effectiveness. To accurately predict the performance of aero-engines under these abrupt conditions, there is an urgent need to establish a high-precision transient performance prediction model. Based on the open thermodynamic system, this paper comprehensively analyzed the key factors that must be considered in the transient process of the aero-engine. A transient performance prediction and energy analysis model considering volume packing, heat transfer, tip clearance variation, fuel system power extraction, and aircraft bleed air was constructed. This study focused on the small bypass ratio turbofan engine, selecting a typical cold acceleration condition that has a significant impact on takeoff performance for simulation analysis. The results indicate that the improved model exhibits significant differences compared to the baseline transient model. During the cold acceleration process, the maximum decrease in the net thrust exceeds 25%, and the specific fuel consumption increases by 34%. From the perspective of energy, at the most significant moment of the transient effect, the available work of the improved model is reduced by 3.37 % compared with the baseline. In addition, the prolonged power reduction due to the sluggish response of tip clearance has a significant negative impact on the take-off of the aircraft. The transient model developed in this study can provide a theoretical support for optimizing control strategies and designing thermal management schemes during rapid maneuvering processes.

In advanced aero-engines, the precise control of tip clearance and thermal management of the fuel system are two important measures to improve the transient performance of the aero-engine. In order to optimize the overall performance of an aero-engine during a full-flight mission, this paper proposed a novel architecture integrating active clearance control system and aero-engine fuel thermal management system, which utilizes fuel heat sink to achieve indirect regulation of the tip clearance. Furthermore, a set of critical optimization criteria for the new architecture was derived to achieve dynamic heat distribution in the fuel thermal management system. Subsequently, the transient performance was tested under a complete flight mission with a duration of 10,000 s. The calculation results indicate that the new architecture effectively raises the fuel temperature to its maximum allowable value during low thermal load phases, which increases heat dissipation capability of the system. The new architecture exhibits a significant effect on the control of the tip clearance during the ground idle, cruise, and engagement phases, resulting in a maximum increase of 1.86% in the relative efficiency of the high-pressure turbine. The new architecture also prevents the engine from experiencing excessively narrow tip clearance during acceleration. Ultimately, the new architecture achieves a 2.59% reduction in total fuel consumption compared to the original design. The new architecture has significant potential to improve engine efficiency and increase operational safety.

Phase change heat transfer devices like heat pipes are widely utilized in temperature control and heat transfer. However, the traditional single uniform wick makes it hard to meet the requirements of capillary pressure and permeability for high-performance heat pipes, thus limiting the improvement of heat transfer performance. In this paper, a gradient structure wick sintered by 316 L stainless steel powder is designed. The capillary performance is tested and characterized through permeability test experiments and capillary rise infrared test experiments. Moreover, the influence of different particle sizes of sintered powder on the capillary performance of the wick structure is studied. The experimental results indicate that the capillary pressure and permeability of the gradient structure wick are significantly improved compared with the traditional single structure wick. Its capillary performance parameter S (KOPcap) is enhanced by more than 30%, providing an effective alternative for the wick of two-phase heat exchange devices.

(1) Analyse the association between C7 pelvic angle (C7PA) and other spinopelvic alignment parameters in patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS), and (2) verify its value in predicting pelvic incidence (PI) – lumbar lordosis (LL) mismatch after selective thoracic fusion (STF). A single center retrospective study was undertaken with patients with Lenke 1 and 2 AIS undergoing STF. PI-LL greater than 9° was defined as PI-LL mismatch. Pearson correlation analysis and receiver operating characteristic (ROC) curves analysis were performed to explore the association between variables and outcomes. Multivariable logistic regression analysis was used to identify the independent risk factor for PI-LL mismatch at final follow-up. A total of 106 patients were enrolled in this study. Patients in the PI-LL match group had higher SVA (-20.26 ± 29.74 mm vs. -33.50 ± 27.16 mm), PI (48.11 ± 8.97 ° vs. 42.64 ± 10.20 °), pelvic tilt (PT) (10.02 ± 6.06 ° vs. 5.74 ± 7.73 °), C7PA (5.83 ± 4.92 ° vs. 0.70 ± 6.78 °) and smaller |PI-LL| (5.3°, 8° vs. 11.2°, 13°) before surgery. The correction of thoracic curve and lumbar curve were comparable between the PI-LL match and mismatch group. There was a strong positive correlation between C7PA and PI-LL both preoperatively (r = 0.736, p < 0.001) and postoperatively (r = 0.903, p < 0.001). The association between SVA, LL and C7PA were also statistically significant (pre-op C7PA-SVA, r = 0.373, p = 0.009; pre-op C7PA-LL, r = -0.251, p < 0.001; po-op C7PA-SVA, r = 0.424, p < 0.001; po-op C7PA-LL, r = -0.396, p < 0.001). When C7PA ≤ 0.3×PT preoperatively, the incidence of sagittal imbalance (p = 0.05) and PI-LL mismatch (p < 0.001) significantly increased at last follow-up. ROC curves analysis revealed that (0.3×PT – C7PA) had the highest area under curve (AUC) when compared with other parameters [(0.3×PT – C7PA), AUC = 0.745; C7PA, AUC = 0.723; PI, AUC = 0.646; PT, AUC = 0.660]. Multivariable logistic regression demonstrated that C7PA ≤ 0.3×PT was the key independent risk factor of PI-LL mismatch at final follow-up [odds ratio = 6.38, 95

The increasing heat loads pose a significant threat to modern aircraft's fuel thermal management system (FTMS), making efficient management of heat generation in the aeroengine fuel system (AFS) crucial for preventing fuel overtemperature. To comprehensively analyze the heat generation distribution in the AFS with pressure regulating and fuel metering valves, a detailed flow and heat transfer simulation model is established based on the thermal fluid network (TFN) method and associated solving algorithms. Calculation results reveal that the total heat generation of a typical AFS can reach up to 9.17 kW under the standard condition, primarily driven by the high-pressure pump and its local fuel return valve due to excessive fuel supply, leading to a significant fuel temperature rise of 12.59 K. The influence of engine speed, fuel flows and incoming fuel temperature on system heat generation and the corresponding fuel temperature rises in each fuel flow path is investigated, indicating that the combustion fuel flow path exhibits larger heat generation, bigger fuel temperature rise and higher sensitivity to these operating parameters compared to other flow paths. Subsequently, a variable speed system (VSS) with a continuously variable transmission (CVT) is designed for the AFS to regulate the fuel supply of the high-pressure pump, which can reduce 88.04 % of the total heat generation compared to the fixed speed system (FSS) under the standard condition. Finally, the impact of inherent heat generation on aircraft thermal endurance is evaluated though dynamic calculations. The results indicate that the FTMS utilizing a VSS extends thermal endurance by 27.93 % during the cruise phase under extreme heat loads compared to that with an FSS. Additionally, the VSS ensures the aircraft's thermal safety throughout a complete mission profile with multiple phases, highlighting the importance of reducing heat generation in the AFS to improve fuel thermal management performance.

(1) To figure out a simple and effective indicator that could assist in the assessment of bone mineral density (BMD) based on big data and (2) to verify its predictive value for low BMD among patients with degenerative lumbar scoliosis (DLS). A total of 6,167 participants from the National Health and Nutrition Examination Survey (NHANES) database (2009–2010, 2013–2014, 2017–2018) and 166 patients who were diagnosed with DLS and hospitalized in our center between June 2019 and April 2023 were enrolled in the study. Cases were divided into two groups based on whether the T-score was below − 1. The Osteopenia Index (OI) was defined as the ratio of alkaline phosphatase (ALP) (IU/L) to creatinine (mg/dL). Multivariable logistic regression was performed to identify risk factors, while restricted cubic spline (RCS) analysis was applied to explore the potential non-linear relationship. Patients with DLS from our center were used to validate the diagnostic value of OI through receiver operating characteristic curve (ROC) analysis. Participants from NHANES were divided into three subgroups according to the tertiles of OI: subgroup 1 (OI < 68), subgroup 2 (68 ≤ OI < 93), and subgroup 3 (OI ≥ 93). A multivariable logistic regression model adjusted for age, gender, and race revealed that elevated OI was a significant risk factor for osteopenia (subgroup 2 vs. subgroup 1: odds ratio [OR] = 1.473, 95

Intervertebral disc degeneration (IDD) is a primary cause of low back pain and, in severe cases, can lead to disability. Current treatments for low back pain remain limited in efficacy, underscoring the need for a deeper understanding of the molecular mechanisms driving IDD. The degeneration process is primarily driven by an imbalance in the extracellular matrix, largely due to the senescence of nucleus pulposus cells (NPCs). Through single-cell sequencing of degenerated nucleus pulposus tissue from five intervertebral discs, we identified five distinct NPC subtypes. Notably, fibrosis-associated NPCs (Fibro-NPC) were predominantly observed at the terminal stage of cell differentiation, identifying Fibro-NPC as a pathogenic subtype in IDD. To further explore intercellular interactions, we used the CellChat algorithm to construct a cell communication network encompassing the diverse cell types in the nucleus pulposus. Mass spectrometry analysis of normal and degenerated tissue subsequently identified seven core proteins associated with IDD. Among these, WGCNA and machine learning highlighted SFRP4 as a central pathogenic protein, highly expressed in Fibro-NPC. Advanced differentiation of nucleus pulposus cells, particularly the Fibro-NPC subtype, is associated with the secretion of SFRP4, which accelerates cellular senescence. This senescence contributes to fibrosis within the nucleus pulposus, along with angiogenesis and inflammatory infiltration in the nucleus pulposus microenvironment. Collectively, these processes drive intervertebral disc degeneration. Our findings position SFRP4 as a biomarker for IDD, presenting a novel target for its diagnosis and treatment.

Active clearance control (ACC) is an effective means of reducing engine fuel consumption. Recently, an innovative fuel-cooled ACC (FCACC) scheme has been developed to improve engine performance by utilizing fuel from the aircraft fuel thermal management system (AFTMS) to precool bleed air, creating a trade-off between fuel supply and thermal management capabilities. To maximize flight endurance through FCACC, this paper firstly elucidates its mechanism for conserving both fuel and fuel heat sink when the thermal management flow path (TMFP) operates in the full recirculation state (FRS), benefiting from the configuration of the recirculation fuel supply branch (RFSB). Calculation results indicate that flight endurance can be extended by 2.28% and 11.62% under the standard condition and extreme mission, respectively. Then, the impact of further utilizing fuel heat sink on flight endurance at the critical transition from FRS to partial recirculation state (PRS) is investigated. In this case, thermal failure, rather than fuel depletion, dominates and shortens flight endurance. Based on this, a novel dynamic regulation strategy for fuel/bleed air heat exchange is established, which is applicable across various operating conditions. Finally, a common mission demonstrates that FCACC can reduce takeoff weight by 20.33 kg, enabling the aircraft to carry additional devices.

With the enhancement of thermodynamic cycle parameters and heat dissipation constraints in aero-engines, effective thermal management has become a critical challenge to ensure safe and stable engine operation. This study developed a transient temperature evaluation model applicable to the entire flight envelope, considering fluid–solid coupling heat transfer on both the main flow path and fuel systems. Firstly, the impact of heat transfer on the acceleration and deceleration performance of a low-bypass-ratio turbofan engine was analyzed. The results indicate that, compared to the conventional adiabatic model, the improved model predicts metal components absorb 4.5% of the total combustor energy during cold-state acceleration, leading to a maximum reduction of 1.42 kN in net thrust and an increase in specific fuel consumption by 1.18 g/(kN·s). Subsequently, a systematic evaluation of engine thermal management performance throughout the complete flight mission was conducted, revealing the limitations of the existing thermal management design and proposing targeted optimization strategies, including employing Cooled Cooling Air technology to improve high-pressure turbine blade cooling efficiency, dynamically adjusting low-pressure turbine bleed air to minimize unnecessary losses, optimizing fuel heat sink utilization for enhanced cooling performance, and replacing mechanical pumps with motor pumps for precise fuel supply control.

This study proposes an infrared imaging and detection model to address infrared imaging and radiation characteristics of the middle and upper atmospheric background. The applicability of the medium spectral resolution atmospheric radiation transfer mode (MODTRAN) in the infrared band is analyzed, and the strategic high-altitude radiance code (SHARC) is utilized to simulate and analyze the infrared radiation characteristics of the middle and upper atmospheric background under different observation parameters in the 3-5 mu m band. Furthermore, a relevant radiation characteristic database is established to complete imaging simulation for infrared radiation scenes in the middle and upper atmospheric background. The results demonstrate that the MODTRAN in the 3-5 and 8-12 mu m bands has good computational accuracy at tangent heights below 50 and 70 km, respectively; middle and upper atmospheric background radiance decreases with the increase in the tangent height and solar zenith angle, however, this increases with the observed zenith angle increase; short and long path radiation characteristics are primarily influenced by the path length and atmospheric parameters in the lower atmosphere, respectively; the radiance during the day and night reaches its global maximum at 36 and 34 km, respectively, and local maximum at 75 and 85 km. The results provide theoretical support for the infrared detection of middle and upper atmospheric backgrounds.

Miniaturization of electronic devices drives the development of ultra-thin flat heat pipes (UTFHPs). As the thickness of the heat pipe decreases, the microchannel effect of the vapor chamber exacerbates the deterioration of the vapor flow. The vapor flow resistance, which is often neglected in the conventional theory due to its extremely small effect compared to the liquid flow resistance, becomes a critical factor limiting the heat transfer performance of UTFHPs. To provide a theoretical basis for the design and performance evaluation of UTFHPs, this paper investigated the effect of the wicking structure and working fluid on the vapor flow resistance of UTFHPs based on theoretical derivations, numerical calculations, and experiments. The results indicate that conventional analytical theory is no longer applicable when the total thickness of the heat pipe is less than 1 mm. The vapor flow resistance obtained using the conventional equation is significantly smaller than the experimental results, which is caused by several factors: raised momentum loss at the wall and gas-liquid interface due to the growth of the velocity gradient in the boundary layer; exacerbated flow instability due to the mixing between the vapor and the working fluid; enhanced fluctuating effects on the flow channel due to the presence of the wicking structure. A dimensionless flow resistance coefficient equation was proposed with the vapor Reynolds number and the channel height ratio. An experiment was conducted to verify the accuracy of the flow resistance correlation. The difference between the experimental results and the calculated values is less than 15 %.

Ultrathin heat pipes have become mainstream to address the heat dissipation issues of small electronic devices. Numerous numerical studies based on the saturated wick assumption have been proposed to analyze their heat transfer performance. In order to achieve a more accurate assessment, this study presents a three-dimensional model that quantitatively reflects the relationship between capillary pressure and medium volume, along with a corresponding correlation. Based on this, a steady-state distributed parameter ultrathin heat pipe model considering the retreating of medium volume in the wick and the unsaturation vapor-liquid interface was developed, whose accuracy was verified by the experimental data. The results demonstrated that the capillary pressure increased with the decrease of medium volume and contact angle. The evolution of the overall meniscus with medium volume was categorized into two stages, where capillary pressure dependent on the main and micro meniscus at different stage. The medium volume distribution, corresponding to capillary pressure, will automatically adjust to match the overall medium pressure drop. Comparative analysis against experimental data, the proposed model reduced the maximum temperature difference error by 8.43 % compared to the saturated wick assumption at a heat load of 6 W, revealing that the unsaturated liquid wick model exhibited higher accuracy.

Objective Recognition of targets by early warning satellites is increasingly crucial in national defense and military applications. This is closely linked to the infrared radiation characteristics of the Earth's background, which highlights the need to establish an accurate model for such radiation. Surface types and weather conditions significantly affect infrared radiation transmission. Therefore, it is necessary to incorporate actual environmental factors when simulating the Earth's background infrared characteristics. This is particularly important in scenarios such as forest fires, which greatly alter these characteristics and pose additional challenges to simulation. While extensive research has been conducted by domestic and international scholars on simulating the infrared radiation characteristics of typical areas, there remains a gap in addressing forest fire scenes. Therefore, to more accurately and efficiently identify target infrared radiation characteristics, it is essential to conduct simulations specifically focused on the Earth's background under forest fire conditions. Methods Based on observational characteristics of the Earth's background within satellite field of view, a parameter law for forest fire scenes is determined using satellite remote sensing data. Surface parameters are established for varying fire intensities such as temperature and emissivity, along with atmospheric parameters like VIS, water vapor content, and CO2 concentration. An extreme scene parameter level model is developed. The cellular automata model used to simulate forest fire scenes is enhanced in three aspects: cell state, cell neighborhood, and cell rules, to effectively simulate large-scale mixed pixels within the satellite's field of view. By employing the extreme scene parameter level model, we calculate radiation brightness under different fire scenes using MODTRAN and store these values in a SQLite database. This approach establishes an infrared radiation simulation model specifically for forest fire scenes within the satellite's field of view. Results and Discussions Through simulation images, it is evident that forest fires significantly increase the radiation brightness of the region, and the area affected by fire expands with its scale (Fig. 8,Fig. 9). In the 2?3 mu m band, fires intensify atmospheric backscattering and surface temperatures, leading to a notable rise in irradiance at the fire site. This complicates the identification of surface types in non-burning areas. The maximum irradiance in small-scale forest fire scenes is 58.6 times higher than that in no-fire ones. Irradiance increases slightly in medium-scale forest fires. In large-scale fires, however, additional ignition points do not significantly increase maximum irradiance, as medium-scale fires already cover the entire area. In the 8?14 mu m band, radiation primarily originates from the surface, and fires release particles that enhance surface radiation absorption. Consequently, changes in maximum irradiance across the detection area are less pronounced compared to the short-wave segment. The maximum irradiance in the small-scale forest fire scene is 1.11x10(3) W /m(2), which is only 1% higher than that in the no-fire scene. In the large forest fire scene with the highest regional irradiance, the maximum irradiance is 1.16x10(3) W /m(2), representing a mere 6% increase compared to the no-fire scene. Regarding the duration of forest fires, in the initial stages, as the fire persists, fire points spread rapidly, expanding the fire area within the detection zone, thereby increasing overall irradiance [Fig. 9(c)?(d), Fig. 10(a)?(b)]. As ignition time progresses further, the fire area within the detection zone does not significantly expand. This is because combustible materials in the original fire site are consumed, transitioning the fire from combustion to completion of combustion. The transition leads to gradual decreases in surface temperature and irradiance (Fig. 10). Areas previously unaffected by fire may ignite due to diffusion, leading to increased surface temperatures and irradiance. Conclusions In the study of infrared radiation from forest fire scenes on Earth, satellite remote sensing data is utilized to establish parameter rules based on observed characteristics of the Earth's background. These rules determine surface parameters such as surface temperature and emissivity, as well as atmospheric parameters like VIS, water vapor content, and CO2 concentration, tailored to different fire intensities. An extreme scenario parameter model is developed for these parameters. The cellular automata model used for simulating forest fire scenes in images is enhanced in three key aspects: cell state, cell neighborhood, and cell rules. These improvements enable the model to accurately simulate large-scale mixed pixels within the satellite's field of view. Using the parameter model for extreme scenarios, the radiant brightness under varying fire conditions is calculated using MODTRAN. This approach allows for the simulation of infrared radiation images of Earth's background during forest fire scenes across arbitrary bands from 2 to 14 mu m, with a wavelength resolution of 0.1 mu m. The radiation data is stored in an SQLite database. Thus, an infrared radiation simulation model is established for forest fires within the field of view. This model considers numerical changes in surface temperature, surface emissivity, aerosols, and other parameters across various ignition stages. Not only do the simulation results enable comparative studies between areas affected by forest fires and those without within the satellite detection field of view, but also simulate infrared radiation scenes under different forest fire conditions by selecting varying fire scales and spread time. This simulation realizes the infrared radiation simulation of Earth's background within the detection area during forest fire scenes, thus providing higher application value.

Ultrathin heat pipe is an effective means to handle the heat dissipation problem of portable mobile devices. Different from conventional heat pipes, the interior vapor chamber of the ultrathin heat pipes is usually <1 mm, so the underlying mechanisms of how the filling rate affecting its heat transfer performance in a narrow space is still unclear. In this paper, a steady-state distributed parameter model considering the unsaturated wick was developed. The volume distribution and heat transfer characteristics of a 60 mmx15 mmx0.26 mm (length x width x thickness) copper-water mesh wick ultrathin heat pipe at different filling rates were analyzed and studied. The results show that under ideal operating conditions, the working medium can automatically adjust the capillary pressure to accommodate varying heat fluxes by modulating the volume distribution in the unsaturated wick at different filling rates, which is a self-regulating process. When the filling rate increased from 0.55 to 0.65, the overall thermal resistance increased by 11.1 %. The thermal resistance in the evaporator and condenser both increase due to the thicker film in the wick. The thermal resistance in the vapor cavity is determined by the countercurrent at the vapor-liquid interface and the exposure degree of the mesh wick. In addition, the optimal filling rate of the studied ultrathin heat pipe is 0.6, which is determined by the variation of capillary pressure distribution, ensuring that the evaporator is not dried out and the condenser is not subcooling. At this condition, the maximum heat flux is 3.2 W/cm(2).

In order to study the aero-engine thermal management systematically, a steady state simulation program is developed based on the Python language. Through the analysis of the mass and energy transmission characteristics, the overall system can be divided into four subsystems: the main flow channel subsystem (including the compressor, the combustor, the turbine and etc.), the fuel subsystem, the lubricating oil subsystem and the air subsystem. And there is a strong coupling of the working parameters between these four subsystems. The control equations of the flow and heat transfer of each subsystem are established based on the mass conservation principle, the momentum conservation principle and the energy conservation principle. Further, the efficient solving algorithms of the subsystems are proposed, which can guarantee the accuracy and convergency of the solutions. With the joint simulation of these four subsystems, the steady state operating parameters of the whole aero-engine thermal management system can be obtained. The accuracy of the steady state simulation program is validated by the experimental results of an actual turbofan engine. The calculation process can provide some ideas for the subsequent software development.

Although high-power devices have experienced rapid development, they still suffer from several limitations in terms of traditional interconnecting materials. This paper describes the preparation of nano-silver paste through liquid-phase chemical reduction using PVP/12-3-12 type gemini quaternary ammonium salt as the mixed stabilizing agent. The high-thermal-conductivity multilayer graphene was mixed into the nano-silver paste to improve the interfacial heat-transfer performance of power devices. The nano-silver paste was sintered at a low temperature (270°C), and its thermal properties were tested. The experimental results show that the thermal resistance of the sintered layers of different pastes decreases linearly with an increase in the loading of multilayer graphene under no-pressure sintering. When the loading of the multilayer graphene was 1

Wound healing has become one of the basic issues faced by the medical community because of the susceptibility of skin wounds to bacterial infection. As such, it is highly desired to design a nanocomposite hydrogel with excellent antibacterial activity to achieve high wound closure effectiveness. Here, based on ultrasound-triggered piezocatalytic therapy, a multifunctional hydrogel is designed to promote bacteria-infected wound healing. Under ultrasonic vibration, the surface of barium titanate (BaTiO3, BT) nanoparticles embedded in the hydrogel rapidly generate reactive oxygen species (ROS) owing to the established strong built-in electric field, endowing the hydrogel with superior antibacterial efficacy. This modality shows intriguing advantages over conventional photodynamic therapy, such as prominent soft tissue penetration ability and the avoidance of serious skin phototoxicity after systemic administration of photosensitizers. Moreover, the hydrogel based on N-[tris(hydroxymethyl)methyl]acrylamide (THM), N-(3-aminopropyl)methacrylamide hydrochloride (APMH) and oxidized hyaluronic acid (OHA) exhibits outstanding self-healing and bioadhesive properties able to accelerate full-thickness skin wound healing. Notably, compared with the widely reported mussel-inspired adhesive hydrogels, OHA/THM-APMH hydrogel due to the multiple hydrogen bonds from unique tri-hydroxyl structure overcomes the shortage that catechol groups are easily oxidized, giving it long-term and repeatable adhesion performance. Importantly, this hybrid hydrogel confines BT nanoparticles to wound area and locally induced piezoelectric catalysis under ultrasound to eradicate bacteria, markedly improving the therapeutic biosafety and exhibits great potential for harmless treatment of bacteria-infected tissues.

III-Nitrides, especially InGaN, are promising for high-efficiency thermoelectric (TE) components operating at high temperatures (HTs), playing a critical role in the recovery of waste heat for sustainable energy development. However, the performance of InGaN TE materials is limited by the high thermal conductivity (k) and the conflict coupling between the power factor (PF) and the k. Here, the previously unstudied two-dimensional InGaN/GaN SL structured TE device with a high In composition of 31% was developed and demonstrated to improve the TE figure of merit (ZT, Z = PF/k) by reducing the k value without deteriorating the PF. The Seebeck coefficient (S) exhibited a value of -365 mu V/K due to the increased density of electron states near the Fermi level by the low dimensional construction. Simultaneously, a relatively low k was obtained as 7.7 W/m.K, benefitting from the alloying and SL interface scattering effect of high energy phonons. Moreover, enhancement of the Umklapp process by the space confinement effect further lowers the k. Accordingly, a record ZT value of 0.089 at 300 K was achieved, which was better than previously reported values for GaN-based TE film materials. This work provides a new material system for improving the performance of nitride TE materials at HTs and extends the fields of application in electricity harvesting from waste heat.

Ionic polymer metal composite (IPMC) always takes big risks of electrode cracking and peeling, which lead to energy wasting, waterloss, and uneven electric field distribution, thus hamper its commercial applications. To address this issue, we propose a facile and effective technique to repair the electrode fatigue by coating polyvinylpyrrolidone (PVP) encapsulated Ag nanoparticles (PVP@AgNPs) on the long-term used IPMC surface. To improve the electrochemical stability, the silver nanoparticles (Ag NPs) with a diameter of ∼34 nm are encapsulated by a 1.3 nm thick PVP film, thus forming a shell–core structure to resist corrosion from the electrolyte solution. Physiochemical investigations reveal that, PVP@AgNPs closely attach to the interior and exterior surfaces of the original Pt nanograin electrode, thus refreshing its electronic conductivity; the repaired IPMC actuator exhibits better electromechanical properties compared to its precursor actuator: 7.62 folds in displacement output, 9.38 folds in force output, and 9.73 folds in stable working time.