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Gas turbine is a promising device for power generation and propulsion either using traditional or renewable energy fuels. One of its key problems is the flow instability of compressors especially with the increase in blade load and changeable working environment. To intelligently and efficiently inhibit flow separation and enhance the pressure rise ability of highly loaded compressors under variable operating conditions, a novel flow control technique termed as adaptive Coanda jet control (ACJC) is proposed in this paper for a compressor stator cascade with a high diffusion factor of 0.66. To realize the ACJC strategy, an incidence angle (IA) prediction model and an optimal injection mass flow rate (OIMFR) prediction model are established by adopting single factor analysis of variance, principal component analysis and Back Propagation Neural Network (BPNN) methods. Two inlet Mach numbers including 0.1 and 0.4 are considered to represent incompressible and compressible flow conditions, and different inlet incidence angles are involved to model various off-design working situations of the real compressor. Effectiveness of the ACJC system is evaluated using numerical simulations are performed to understand the effects of the injection mass flow ratio on the flow field and aerodynamic performance of the blade cascade. Results indicate that the ACJC system can accurately predict the optimal injection mass flow ratio that can achieve the minimum flow loss at each incidence angle. Compared to the cascade without ACJC under the incidence angel of 5°, the optimal injection mass flow ratio being 1.27% and 1.20% can reduce the total pressure loss coefficient by 18.88% and 21.56% for incoming Mach number being 0.1 and 0.4, respectively.

Soft network metamaterials are widely used in fields such as flexible electronics, tissue engineering, and biomedicine due to their superior properties including low density, high stretchability, and high breathability. However, the prediction and customization of the nonlinear mechanical behavior of soft network metamaterials remain a challenging problem. In this study, a family of hydrogel-based network metamaterials with biological tissue-like mechanical properties are developed based on a machine learning-driven optimization design method. Numerical and experimental results explain the relationship between the mechanical properties of the designed metamaterials and their microstructural features and stretching ratios. The results indicate that the hydrogel-based network metamaterials exhibit J-shaped stress-deformation (σ–λ) behavior similar to biological tissues. This phenomenon arises from the transition of the deformation mode of metamaterials from bending-dominated to stretching-dominated as the stretching ratio increases. Based on the proposed design scheme, the Poisson’s ratio of metamaterials can be adjusted within a remarkably wide range of −1.06 to 1.34. Furthermore, through optimizing the design parameters of the metamaterial, the customization of network metamaterials with biological tissue-like zero Poisson’s ratio behavior and stress response is achieved. The potential applications of hydrogel-based network metamaterials are demonstrated through artificial skin and LED integrated device. This research offers novel insights into predicting, designing, and fabricating the mechanical behavior of soft network metamaterials.

Icing, a common natural phenomenon, always originates from a molecule. Molecular simulation is crucial for understanding the relevant process but still faces a great challenge in obtaining a uniform and accurate description of ice and liquid water with limited model parameters. Here, we propose a series–parallel machine learning (ML) approach consisting of a classification back-propagation neural network (BPNN), parallel regression BPNNs, and a genetic algorithm to establish conventional TIP5P-BG and temperature-dependent TIP5P-BGT models. The established water models exhibit a comprehensive balance among the crucial physical properties (melting point, density, vaporization enthalpy, self-diffusion coefficient, and viscosity) with mean absolute percentage errors of 2.65 and 2.40%, respectively, and excellent predictive performance on the related properties of liquid water. For ice, the simulation results on the critical nucleus size and growth rate are in good accordance with experiments. This work offers a powerful molecular model for phase transition and icing in nanoconfinement and a construction strategy for a complex molecular model in the extreme case.

In this paper, a numerical simulation method is used to calculate a 1.5-stage axial transonic compressor to explore its unsteady flow mechanism. The performance curve is compared with the experimental data to verify the calculation method with a high numerical accuracy, which shows that the unsteady calculation has good reliability. According to the analysis of the data from the monitoring points under the near-stall condition, the unsteady disturbances originate from the tip region of blade and perform the strongest at the blade pressure surface with a broadband characteristic. Further analysis is conducted by combining with the characteristics of the transient flow field at the tip of blade. The results show that the unsteady pressure fluctuations are caused by the migration of the new vortex cores. These new vortex cores are generated by the breakdown of leakage vortex in the downstream, which is induced by the leakage vortex and shock wave interference. Moreover, the relationship between the unsteady flow characteristics and the working conditions is also studied. The leakage vortex intensity and the shock wave strength gradually increase with the decrease of flow rate. When the combination of the leakage vortex intensity and shock wave strength reaches the first threshold, a single frequency of unsteady disturbances appears at the blade tip. When the combination of the leakage vortex intensity and shock wave strength reaches the second threshold, the frequency of unsteady disturbances changes to a broadband.

A novel green long afterglow material CaGeO3:Tb3+was synthesized by high temperature solid phase method. According to the experimental results, CaGeO3:Tb3+is a green long persistent luminescent (LPL) material with excellent performance. CaGeO3:Tb3+shows LPL emission peak at 442, 490.9, 548.7, 588.5 and 623.8 nm, corresponding to 5D3to 7F4and 5D4to 7FJ(J = 6, 5, 4, 3) transitions of Tb3+. Its CIE coordinates are (0.27, 0.50), indicating that the afterglow emission is close to the light of green region. In addition, after the excitation source is turned off, the afterglow time is longer than 90 min. After an interval of 7 h, the photo-stimulation luminescence (PSL) can be observed by using 980 nm laser cyclic excitation. The thermoluminescence (ThL) results show that there are three types of traps in the material and their depths are 0.666, 0.774 and 0.892 eV respectively, which are caused by the doping of Tb3+. All the results show that CaGeO3:Tb3+is an excellent long afterglow luminescent material.

An adaptive phase-field total Lagrangian material point method (APTLMPM) is proposed in this paper for effectively simulating the dynamic fracture of two-dimensional soft materials with finite deformation. In this method, the governing equations for the fracture of soft materials are derived by integrating the phase-field fracture model with the total Lagrangian material point method (TLMPM), and corresponding discrete equations are then formulated with explicit time integration. To address the significant computational issue in terms of memory and processing time, an adaptive technique for dynamically splitting particles and background grids in the phase-field TLMPM is proposed, based on the phase-field values of the particles. To further maintain continuity of the physical field throughout the computational process and consider the characteristics of the field update, an information remapping strategy is developed. Several representative numerical examples are presented to demonstrate the accuracy and efficiency of the proposed APTLMPM by comparing the simulation results with experimental data and those as obtained with other numerical methods.

In this paper, a diffuser passage compressor design is introduced via optimization to improve the aerodynamic performance of the exit rotor in a multistage axial compressor. An in-house design optimization platform, based on genetic algorithm and back propagation neural network surrogate model, is constructed to perform the optimization. The optimization parameters include diffusion angle of meridian passage, diffusion length of meridian passage, change of blade camber angle and blade number. The impacts of these design parameters on efficiency and stability improvement are analyzed based on the optimization database. Two optimized diffuser passage compressor designs are selected from the optimization solution set by comprehensively considering efficiency and stability of the rotor, and the influencing mechanisms on efficiency and stability are further studied. The simulation results show that the application of diffuser passage compressor design can improve the load coefficient by 12.1% and efficiency by 1.28% at the design mass flow rate condition, and the stall margin can be improved by 12.5%. According to the local entropy generation model analysis, despite the upper and lower endwall loss of the diffuser passage rotor are increased, the profile loss is reduced compared with the original rotor. The efficiency of the diffuser passage rotor can be influenced by both loss and load. At the near stall condition, decreasing flow blockage at blade root region can improve the stall margin of the diffuser passage rotor.

An optimized axial slot casing treatment (OPCT) was designed that experimentally improves the stall margin by 7.31% with an efficiency gain of 1.94% at a design speed of 100% in a high-speed axial flow fan. Subsequently, the OPCT was tested under the distorted inflow with a 9% composite distortion index; it can still improve the stall margin by 6.19% with an efficiency gain of 1.63% at the 100% design speed. The unsteady measurement results indicate that the location of the shock wave obviously moves forward toward the leading edge of the blade tip as the rotor blade rotates out of the distorted region and induces the stall in advance. When the OPCT is applied, the strength of the interaction between the shock wave and tip leakage flow can be suppressed, and the location of the shock wave at the distorted region is pushed backward. Thus, the trigger of the stall inception generated in the downstream of the distortion region is postponed. Meanwhile, a new phenomenon was discovered that the OPCT does not alter the instability mode of the fan, and the fan eventually surges, which is consistent with the B parameter value of 2.942. However, under the distorted inflow, the B parameter can be reduced from 2.942 to 0.863, thereby the instability mode of the fan is changed from surge to stall. It can guide the instability prediction when the boundary condition (distortion or casing treatment) of the fan is changed.

Adaptive stability control is experimentally implemented in a single-stage axial flow compressor subjected to rotating inlet distortion. Stall margin variations are examined as a function of the distorted area and rotational speed. A critical minimum value is identified when the distorted sector rotates at 0.5 times the rotor speed (P0.5RS), which remains independent of the size of the distorted area and induced frequency. Unsteady pressure measurements indicate that with the rotating inlet distortion at P0.5RS, the circumferentially propagating speed of the stall cell-induced downstream of the distorted region closely matches the rotational speed of the distorted sector, which causes the stall cell to undergo repeated cycles of generation, circumferential propagation, decay, and re-generation, ultimately leading to premature deep stall as the disturbance energy accumulates. In addition, tip air injection can suppress the repeated periodic disturbance energy accumulation, thereby delaying stall. Based on successful verification of the early stall warning under rotating inlet distortion through cross-correlation analysis, an adaptive stability control strategy is devised to sense the stall warning signal in real time and feed back the signal to control the injected valve once the alarm line is triggering. Even under the rotating distorted inflow at P0.5RS, the stall margin can be improved online by more than 10% while reducing the injected energy by 80% compared with that corresponding to steady injection. It provides insights for mitigating the adverse effects of rotating distortion on the compressor performance in multispool aero-engines.

The hybrid slot-groove (S-G) casing treatment (CT), which combines the advantages of slot and groove in consideration of stall margin enhancing and efficiency penalty, was experimentally investigated under circumferential distorted inflows. Previous experiments showed that the hybrid S-G CT can extend the stability by 19.79% with uniform inflow condition. To further estimate its stability enhancement ability with distorted inflow, three types of circumferential total pressure distortion inflow that the distorted intensities (DC(60)) are equal to 0.90%, 4.12%, and 24.75%, are selected to conduct a serial of experiments. Results demonstrated that the stability of the compressor were deteriorated by 7.87%, 9.19% and 39.08% respectively under three distorted inflows. It was founded that, under the above-mentioned distorted inflows, the hybrid S-G CT was able to extend the stability by 18.48%, 17.81%, and 13.80%, respectively, which proved the strong anti-distortion ability of the hybrid S-G CT. By using the dynamic pressure sensors fixed on the casing wall, the unsteady measurements demonstrated that the stall precursor with uniform and circumferential distorted inflows are always spiky-wave; thus the hybrid S-G CT can play an excellent stability enhancement capability. The analytical results with power spectral density proved that, when at the same flow point, the perturbation, with frequency being around the rotating stall frequency band, was distinctly suppressed by hybrid S-G CT, thus delaying the rotating stall. The stall precursor detected in the casing wall depicted that unlike the short length-scale of stall precursor (5–6 blade passage) under smooth casing; the hybrid S-G CT can create a stall precursor with long length-scale. Under the distortion intensities from 0 to 4.12%, the length scale of the stall precursors occupies approximately 10–12 blade passages. As the distortion intensity further increases to 24.75%, the length scale of stall precursor increases to occupy 16–17 blade passages. This phenomenon can guide the stall warning studies with compressors using CT in the future.

Different CO2carbon mitigation strategies are required due to the uneven development of regions. In China, the western region is rich in natural resources, but its industrial technology is not as advanced as other regions. In addition, a few studies have attempted to explore the CO2carbon mitigation strategies for a municipality of this region. In terms of modeling, the current studies often focus on the low-carbon potentials at the country, province, city and sector levels, while the carbon flows and their integration in neighboring regions are not well studied. In this paper, to explore the impact of regional-difference factors on CO2reduction, we propose regional-based CO2mitigation for a municipality and use Chongqing as a case study. In our methodology, the hierarchical structure analysis is conducted to identify the primary contradictions of regional CO2emissions. Then, using system dynamics, CO2emission systems of major industries, including cement, power and transportation, are modeled. Through simulations of baseline and low-carbon scenarios, key influencing factors in each industry are analyzed. They are then generalized to identify the important aspects of CO2emission reduction for this region. Finally, the low-carbon development strategy covering three sub-pathways, i.e., the industrial system, energy structure and socio development is discussed to help the local government for policy-making.

We developed bright yellow-emitting long persistent luminescence (LPL) materials Sr4Al14O25:Mn2+and Sr4Al14O25:Mn2+,N (N = Zr4+, Ho3+, Er3+) by high temperature solid–state reaction. The addition of Zr4+, Ho3+and Er3+can regulate trap distributions and improve energy storage ability of the materials. The LPL performance of SAO:Mn2+,Ho3+is optimal, considering LPL intensity and duration time. Bright LPL of SAO:Mn2+,Ho3+can be observed for 3 h by naked eyes in dark after removing the excitation source. Profiles of LPL spectra are different from those of PL, because the two types of Mn2+centers do not play equal parts in LPL and photoluminescence (PL). Trap depths of TL peaks centered at 354 K (peak 1) and 455 K (peak 2) are 0.60 and 0.72 eV, respectively. And peak 1 at 354 K is the effective TL peak responsible for LPL. In SAO:Mn2+,Ho3+,Mn2+ions doped in Al3+sites serve as emitting centers, and positively charged HoSr·defects are the main effective trap centers. Finally, a feasible LPL mechanism of SAO:Mn2+,Ho3+was proposed to clarify the generation process of LPL.

• The intrinsic interaction between a dislocation and a twin boundary (TB) is investigated with an accurate atom-continuum coupling model. • The dependence of dislocation-TB interaction on Burgers vectors of dislocations is investigated. • The long-range interaction between a TB and a general dislocation is proven to be negligibly weak compared to the interaction between dislocations. • It is shown that experimentally observed repulsion to dislocations from TBs is actually from dislocation-type defects on TBs. • Previously proposed or adopted interaction laws between dislocations and TBs are conceptually unified in a framework. The combination of ultrahigh strength and excellent ductility of nanotwinned materials is rooted in the interaction between dislocations and twin boundaries (TBs). Quantifying the interaction between TBs and dislocations not only offers fresh perspectives of designing materials with high strength and ductility, but also becomes the cornerstone of multiscale modeling of materials with TBs. In this work, an atom-continuum coupling model was adopted to quantitatively investigate the interaction between dislocations and TBs. The simulation shows that the dislocation–TB interaction is much weaker than the interaction between dislocations at the same distance. Simulation of the early stage of dislocation pileups further verifies that the experimentally observed repulsive forces are essentially from the dislocations or kink-like steps on TBs. The interaction between TBs and dislocations with different Burgers vectors was demonstrated referring to the elastic theory of dislocations. With the intrinsic interaction between dislocations and TBs being clarified, this work will promote further development of the multiscale simulation methods, such as discrete dislocation dynamics or phase-field method, of materials with TBs by providing a quantitative description of the interactions between TBs and dislocations. [ABSTRACT FROM AUTHOR]

Surge is an unstable operating condition of the aero-engine that can move the engine into a destabilized state and cause devastating damage. One of the most popular topics in the academic and industrial communities is to figure out the mechanism of the surge and withdraw from the surge safely. Based on rig test results and practical data from engine operation, various theories of surge mechanisms have been proposed by researchers, and some classical analytical models have been developed for modelling and prediction. In recent years, with the rapid development of numerical simulation and the improvement of computational capability, computational fluid dynamics (CFD) has been widely applied to the investigation of axial compressor surge events.

The rotor blade height with low hub-tip ratio is relatively longer, and the aerodynamic parameters change drastically from hub to tip. Especially the organization of flow field at hub becomes more difficult. This paper takes a transonic 1.5-stage axial compressor with low hub-tip ratio as the research object. The influence of four types of rotor hub contouring on the performance of transonic rotor and stage is explored through numerical simulation. The three-dimensional numerical simulation results show that different hub contourings have obvious influence on the flow field of transonic compressor rotor and stage, thus affecting the compressor performance. The detailed comparison is conducted at the rotor peak efficiency point for each hub contouring. Compared with the linear hub contouring, the concave hub contouring can improve the flow capacity, improve the rotor working capacity, and increase the flow rate. The flow field near blade root and efficiency of transonic rotor is improved. The convex hub contouring will reduce the mass flow rate, pressure ratio and efficiency of the transonic rotor. Full consideration should be given to the influence of stator flow field by hub contouring.

Coanda jet flap is an effective flow control technique, which offers pressurized high streamwise velocity to eliminate the boundary layer flow separation and increase the aerodynamic loading of compressor blades. Traditionally, there is only single-jet flap on the blade suction side. A novel Coanda double-jet flap configuration combining the front-jet slot near the blade leading edge and the rear-jet slot near the blade trailing edge is proposed and investigated in this paper. The reference highly loaded compressor profile is the Zierke & Deutsch double-circular-arc airfoil with the diffusion factor of 0.66. Firstly, three types of Coanda jet flap configurations including front-jet, rear-jet and the novel double-jet flaps are designed based on the 2D flow fields in the highly loaded compressor blade passage. The Back Propagation Neural Network (BPNN) combined with the genetic algorithm (GA) is adopted to obtain the optimal geometry for each type of Coanda jet flap configuration. Numerical simulations are then performed to understand the effects of the three optimal Coanda jet flaps on the compressor airfoil performance. Results indicate all the three types of Coanda jet flaps effectively improve the aerodynamic performance of the highly loaded airfoil, and the Coanda double-jet flap behaves best in controlling the boundary layer flow separation. At the inlet flow condition with incidence angle of 5°, the total pressure loss coefficient is reduced by 52.5% and the static pressure rise coefficient is increased by 25.7% with Coanda double-jet flap when the normalized jet mass flow ratio of the front jet and the rear jet is equal to 1.5% and 0.5%, respectively. The impacts of geometric parameters and jet mass flow ratios on the airfoil aerodynamic performance are further analyzed. It is observed that the geometric design parameters of Coanda double-jet flap determine airfoil thickness and jet slot position, which plays the key role in supressing flow separation on the airfoil suction side. Furthermore, there exists an optimal combination of front-jet and rear-jet mass flow ratios to achieve the minimum flow loss at each incidence angle of incoming flow. These results indicate that Coanda double-jet flap combining the adjust of jet mass flow rate varying with the incidence angle of incoming flow would be a promising adaptive flow control technique.

Bifunctional ZnxMoy-TiO2were prepared through sol-gel methodology for efficient furfuryl alcohol (FAL) alcoholysis to ethyl levulinate (EL). From the comprehensive analysis, the abundant Brønsted and Lewis acidity distribution, enhanced reducibility ability, and the synergistic effect between Zn and Mo were found in Zn1Mo1–TiO2. Specially, Zn played an important role in enhancing acidity strength and reducibility from NH3-TPD and H2-TPR profiles, whereas Mo exhibited the highest FAL adsorption capacity. The simulative structure with the adjacent Zn–Mo and non-adjacent Zn–Mo with O vacancies in TiO2showed no difference in FAL adsorption energy and bader charge transfer capacity. After optimization, Zn1Mo1–TiO2exhibited the highest FAL conversion (98 %) and EL yield (80 %) with negligible 2-(ethoxymethyl)furan (EMF) and 5-ethoxy-5-(ethyl-oxidaneylidene) pentan-2-one (intermediate 4) yield under optimum condition (50 mg Zn1Mo1–TiO2, 170 °C, 7 h). Most importantly, the catalyst recyclability was performed in continuous flow until 700 min without obvious EL yield decrease. The rational design of the cost-effective bimetallic based TiO2will drive the green and efficient EL production in industrial scale.

The influence of Axial-Slot Casing Treatment (ASCT) on the performance and stability enhancement mechanisms of ASCT were experimentally and numerically investigated in a high-speed mixed-flow compressor under three different tip clearances. Unsteady simulations showed the compressor stalled through end-wall stall route, i.e. the spike stall inception originating from rotor tip region, which was validated by dynamical measurements. When the ASCT was applied, greater than 20% of Stall Margin Improvement (SMI) could be achieved for the compressor under each tip clearance size. The streamwise velocity contours and flow structures in the tip region and axial slots were deeply analyzed to explore how the so called “suction and injection effects” generated by the ASCT manipulate tip clearance flow and enhance the stability of compressor under different tip clearances. It was found that the dominant stability enhancement mechanisms of ASCT varies with tip clearance size for the mixed-flow compressor. (A) For the small tip clearance, the dominant mechanism of stability enhancement is the blockage reduction generated in the blade passage by the suction effect of ASCT. (B) For the large tip clearance, the injection effect of the ASCT is the dominant mechanism of stability enhancement with ASCT, which plays the leading role in delaying the spillage of incoming/tip leakage flow interface at the rotor Leading Edge (LE) plane.

Here, an X-ray-excited super-long afterglow phosphor β-NaYF4:Tb3+has been discovered for the first time. After X-ray irradiation, the green emission can persist for more than 240 h. After 120 h, the power density of afterglow reached 3.76 × 10–6W·m–2, which can be clearly observed by the naked eye under dark vision. Also, combined with the results of thermoluminescence and photoluminescence, the super-long afterglow emission of β-NaYF4:Tb3+can be ascribed to the tunneling model associated with F centers. More importantly, the super-long green afterglow emission of β-NaYF4:Tb3+has been successfully used as an in vivolight source to activate g-C3N4for photodynamic therapy and bacteria destruction. Furthermore, super-long persistent luminescence of β-NaYF4:Tb3+could be repeatedly charged by X-rays for many cycles, which indicates that the phosphors have high photostability under repeated cycles of alternating X-ray irradiation.

The timely detection of stall inception is of great significance for safe operation and stability control of axial compressor. In the current study, a fast wavelet tool was selected to predict stall precursor in axial compressors with spike-type and modal-wave stall inception. Dynamic pressure was measured in the casing wall by using a collection of time-resolved pressure transducers with circumferential and chord-wise spatial resolution. Fast wavelet analysis with low frequency reconstruction results demonstrate that the initial inception can be detected 110 rotor revolutions prior to stall for modal-wave stall inception in a 1.5 stage axial compressor. For spike-type stall inception, despite the failure of early stall warning via low frequency reconstruction, an increase amplitude frequency band of 0.2-0.8 blade passing frequency was identified using high frequency reconstruction in an isolated-rotor axial compressor. Fast wavelet method can predict two kinds of stall inceptions simultaneously in advance and realize the early stall warning in axial compressors through a reasonable selection of reconstructed frequency.

Casing treatments (CT) can effectively extend compressors flow ranges with the expense of efficiency penalty. Compressor efficiency is closely linked to loss. Only revealing the mechanisms of loss generation can design a CT with high aerodynamic performance. In the paper, a highly-loaded mixed-flow compressor with tip clearance of 0.4 mm was numerically studied at a rotational speed of 30,000 r/min to reveal the effects of axial slot casing treatment (ASCT) on the loss mechanisms in the compressor. The results showed that both isentropic efficiency and stall margin were improved significantly by the ASCT. The local entropy generation method was used to analyze the loss mechanisms and to quantify the loss distributions in the blade passage. Based on the axial distributions of entropy generation rate, for both the cases with and without ASCT, the peak entropy generation rate increased in the rotor domain and decreased in the stator domain during throttling the compressor. The peak entropy generation in rotor was mainly caused by the tip leakage flow and flow separations near the rotor leading edge for the mixed-flow compressor no matter which casing was applied. The radial distributions of entropy generation rate showed that the reduction of loss in the rotor domain from 0.4 span to the rotor casing was the major reason for the efficiency improved by ASCT. The addition of ASCT exerted two opposite effects on the losses generated in the compressor. On the one hand, the intensity of tip leakage flow was weakened by the suction effect of slots, which alleviated the mixing effect between the tip leakage flow and main flow, and thus reduced the flow losses; On the other hand, the extra losses upstream the rotor leading edge were produced due to the shear effect and to the heat transfer. The aforementioned shear effect was caused by the different velocity magnitudes and directions, and the heat transfer was caused by temperature gradient between the injected flow and the incoming flow. For case with smooth casing (SC), 61.61% of the overall loss arose from tip leakage flow and casing boundary layer. When the ASCT was applied, that decreased to 55.34%. The loss generated by tip leakage flow and casing boundary layer decreased 20.54%) relatively by ASCT.

Lead halide perovskite nanocrystals (NCs) have been widely investigated owing to their potential applications as optoelectronic devices. However, these materials suffer from poor water stability, which make them impossible to be applied in biomedicine. Here, insoluble CsPbBr3/CsPb2Br5composite NCs were successfully synthesized via simple water-assisted chemical transformation of perovskite NCs. Water plays two key roles in this synthesis: (i) stripping CsBr from CsPbBr3/Cs4PbBr6and (ii) modifying the coordination number of Pb2+(six in CsPbBr3and Cs4PbBr6vs eight in CsPb2Br5). The as-prepared CsPbBr3/CsPb2Br5composite NCs not only retain the photoluminescence quantum yield (up to 80%) and a narrow full width to half-maximum of 16 nm, but also present excellent water stability and low cytotoxicity. With these properties, the CsPbBr3/CsPb2Br5composite NCs were demonstrated as efficient fluorescent probes in live HeLa cells. We believe that our finding not only provides a new method to prepare insoluble, narrow-band, and brightly luminescent CsPbBr3/CsPb2Br5composite NCs, but also extend the potential applications of lead halides in biomedicine.

To assess the aerodynamic performance and vibration characteristics of rotor blades during rotation, a study of unsteady blade surface forces is conducted in a low-speed axial flow compressor under a rotating coordinate system. The capture, modulation, and acquisition of unsteady blade surface forces are achieved by using pressure sensors and strain gauges attached to the rotor blades, in conjunction with a wireless telemetry system. Based on the measurement reliability verification, this approach allows for the determination of the static pressure distribution on rotor blade surfaces, enabling the quantitative description of loadability at different spanwise positions along the blade chord. Effects caused by the factors such as Tip Leakage Flow (TLF) and flow separation can be perceived and reflected in the trends of static pressure on the blade surfaces. Simultaneously, the dynamic characteristics of unsteady pressure and stress on the blade surfaces are analyzed. The results indicate that only the pressure signals measured at the mid-chord of the blade tip can distinctly detect the unsteady frequency of TLF due to the oscillation of the low-pressure spot on the pressure surface. Subsequently, with the help of one-dimensional continuous wavelet analysis method, it can be inferred that as the compressor enters stall, the sensors are capable of capturing stall cell frequency under a rotating coordinate system. Furthermore, the stress at the blade root is higher than that at the blade tip, and the frequency band of the vibration can also be measured by the pressure sensors fixed on the casing wall in a stationary frame. While the compressor stalls, the stress at the blade root can be higher, which can provide valuable guidance for monitoring the lifecycle of compressor blades.

A complete understanding of the interactions between nanoparticles (NPs) and the cell membrane is essential for the potential biomedical applications of NPs. The rotation of the NP during the cellular wrapping process is of great biological significance and has been widely observed in experiments and simulations. However, the underlying mechanisms of the rotation and their potential influences on the wrapping behavior are far from being fully understood. Here, by coupling the rotation of the NP with the diffusion of the receptors, we set up a model to theoretically investigate the wrapping pathway and the internalization rate of the rotatable NP in the receptor-mediated endocytosis. Based on this model, it is found that the endocytosis proceeds through the symmetric–asymmetric or asymmetric–symmetric–asymmetric wrapping pathway due to the bending and membrane tension competition induced rotation of NP. In addition, we show that the wrapping rate in the direction that the wrapping proceeds can be largely accelerated by the rotation. Moreover, the time to fully wrap the NP depends not only on the size and shape of the NP but also on its rotation and initial orientation. These results reveal the roles of the shape, rotation, and initial orientation of the NP on the receptor-mediated endocytosis and may provide guidelines for the design of NP-based drug delivery systems.

In this paper, we developed low dose X-ray induced long afterglow phosphor Ca2P2O7:Pr3+, which shows excellent afterglow luminescence from ultraviolet C (UVC) to red region. The photoluminescent results show that under 445.7 nm excitation, Ca1.995P2O7:0.5%Pr3+displays red emissions peaked at 598.3 and 651.9 nm, corresponding to 1D2-3H4and 3P0-3F2transitions of Pr3+, respectively. Due to its pure red emission (CIE coordinates (0.59101,0.39926)), Ca1.995P2O7:0.5%Pr3+can be regarded as a potential LED red phosphor. More importantly, Ca2P2O7:Pr3+shows long afterglow luminescence from UVC to red region, which consists of four continuous emissions with similar intensity including 260, 359, 466 and 598.3 nm. Since these afterglow continuous emissions are fitted to the absorption of most photodynamic therapy (PDT) agents, Ca2P2O7:Pr3+can be regarded as excellent PDT agents. Furthermore, 30 s X-ray irradiation can induce 5400 s decay of Ca1.997P2O7:0.3%Pr3+, and its afterglow emission intensity still reaches 5×104cps after 5400 s decay. Even only 5 s X-ray irradiation also can produce 4.75×104cps afterglow emission after 10 s decay. In addition, the repeat 980 nm laser irradiations can induce continuous strong photo-stimulated (PSL) luminescent peaks, which can be utilized to conduct high efficiency PDT without another X-ray irradiation. The thermoluminescence results reveal that the existence of shallow (0.89 eV) and deep traps are responsible for the excellent X-ray induced long afterglow and PSL luminescence. All these results suggest that Ca2P2O7:Pr3+possesses great potential to be regarded as high efficiency PDT agents.

The low-dose X-ray induced long afterglow near infrared (NIR) luminescence from Cr3+doped Zn1–xCdxGa2O4spinel solid solutions was investigated. The structure analysis shows the good formation of Zn1–xCdxGa2O4spinel solid solutions, which possesses a cubic spinel structure with Fd3mspace group. The formation of Zn1–xCdxGa2O4spinel solid solutions induces the obvious increase of long afterglow near infrared luminescence excited by low-dose X-ray. When the content of doped Cd2+reaches 0.1, the low-dose X-ray induced long afterglow NIR luminescence is the maximum. More importantly, only 5 s X-ray irradiation can induce more than 6 h NIR afterglow emission, of which the afterglow luminescent intensity is still 5 times stronger than the background intensity after 6 h. The thermoluminescent results show that under the 5 s exposure of X-ray, the trap density of Zn0.9Cd0.1Ga2O4:Cr3+is much higher than that of ZnGa2O4:Cr3+. The replacement of Cd2+ions with large radius at Zn2+sites causes the increase of defects and dislocations, which results in the obvious increase of trap concentrations. And the addition of high-znumber elements Cd2+would enhance the X-ray absorption of the solid solutions, which thus can be easily excited by low-dose X-ray. Zn0.9Cd0.1Ga2O4:1%Cr3+solid solution is a potential candidate of low-dose X-ray induced long afterglow luminescent materials.

Multifunctional theranostic nanoplatforms greatly improve the accuracy and effectiveness in tumor treatments. Much effort has been made in developing advanced optical imaging-based tumor theranostic nanoplatforms. However, autofluorescence and irradiation damage of the conventional fluorescence imaging technologies as well as unsatisfied curative effects of the nanoplatforms remain great challenges against their wide applications. Herein, we constructed a novel core–shell multifunctional nanoplatform, that is, chromium-doped zinc gallogermanate (ZGGO) near-infrared (NIR) persistent luminescent nanoparticles (PLNPs) as a core and zeolitic imidazolate framework-8 (ZIF-8) as a shell (namely ZGGO@ZIF-8). The ZGGO@ZIF-8 nanoplatform possessed dual functionalities of the autofluorescence-free NIR PersL imaging as well as the pH-responsive drug delivery, thus it has high potential in tumor theranostics. Notably, the loading content of doxorubicin (DOX) in ZGGO@ZIF-8 (LC = 93.2%) was quite high, and the drug release of DOX-loaded ZGGO@ZIF-8 was accelerated in an acidic microenvironment such as tumor cells. The ZGGO@ZIF-8 opens up a new material system in the combination of PLNPs with metal–organic frameworks and may offer new opportunities for the development of advanced multifunctional nanoplatforms for tumor theranostics, chemical sensing, and optical information storage.

Persistent luminous nanoparticles (PLNPs) have been capturing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits (e.g., zero-autofluorescence background, high signal-to-noise ratio). Although there are quite some synthetic methodologies to synthesize PLNPs, those for constructing functional structured PLNPs remain largely unexplored. Herein we report the design principle, synthesis route, and proof-of-concept applications of hollow structured PLNPs with near-infrared (NIR) persistent luminescence, namely afterglow, and tunable sizes for tumor afterglow imaging and chemical/photodynamic therapies. The design principle leverages on the crystallization of the immobilized parent ions on the purgeable carbon spheres. This strategy provides large and size-tunable hollow cavities to PLNPs after calcination. Building on the hollow cavity of PLNPs, high chemical drug (DOX) or photosensitizer (Si-Pc) loading can be achieved. The DOX/Si-Pc-loaded hollow PLNPs exhibit efficient tumor suppression based on the features of large cavity and afterglow of PLNPs. These hollow structured PLNPs, like traditional solid PLNPs, are quite stable and can be repeatedly activated, and particularly can selectively target tumor lesion, permitting rechargeable afterglow imaging in living mice. Our research supplies a strategy to synthesize hollow structured PLNPs, and hopefully it could inspire other innovative structures for cancer theranostics.

Cardiac safety assessments are significant in drug discovery, as drug‐induced cardiotoxicity (DIC) is the primary cause of drug attrition. Despite heart‐on‐a‐chip (HoC) technology becoming an increasingly popular tool for evaluating DIC, its development remains a challenge owing to the anisotropic cardiac structure of the native myocardium. Herein, an anisotropic multiscale cardiac scaffold is presented via a hybrid biofabrication method by combining 3D printing with electrospinning technology, where the 3D‐printed micrometer‐scale scaffold frames enable mimicking the interwoven myocardium anatomical structure and the branched‐aligned electrospun nanofibers network is able to directionally guide cellular arrangements. The in vitro 3D bioengineered cardiac tissues are then fabricated by encapsulating three‐layer multiscale scaffolds within a photocurable methacrylated gelatin hydrogel shell. It is demonstrated that such an anisotropic multiscale structure could contribute to enhancing cardiomyocyte maturation and synchronous beating behavior. More attractively, with the integration of 3D bioengineered cardiac tissues and a self‐designed microfluidic perfusion system, a 3D anisotropic HoC platform is established for evaluating DIC and cardioprotective efficacy. Collectively, these results indicate that the HoC model developed by integrating the 3D bioengineered cardiac tissues could effectively recapitulate the clinical manifestations, thereby highlighting their efficacy as a valuable preclinical platform for testing drug efficacy and cardiotoxicity. A multiscale anisotropic scaffold is developed by integrating 3D printing and electrospinning techniques, where such an anisotropic multiscale structure could contribute to enhancing cardiomyocyte maturation and synchronous beating behavior. The 3D bioengineered cardiac tissue is then integrated into a self‐designed microfluidic perfusion system to develop a 3D anisotropic heart‐on‐a‐chip platform for evaluating drug‐induced cardiotoxicity and cardioprotective efficacy.

Heart‐on‐a‐Chip In article 2300719, a 3D anisotropic heart‐on‐achip platform is fabricated by Ling Wang, Wenhua Huang, Yaobin Wu, and co‐workers using a hybrid biofabrication approach that combines 3D printing and electrospinning. This platform can mimic the structure and function of native heart tissues and evaluate drug‐induced cardiotoxicity.

This paper proposes an efficient model reduction strategy in conjunction with non-intrusive statistical moment methods for the stochastic nonlinear transient heat conduction problem. In the proposed strategy, the deterministic reduced basis vectors (RBVs) are adopted to approximate the random temperature response, and the thermal conductivity of the random nonlinear heat conduction matrix in the RBVs space is decoupled from the geometric characteristic matrix (GCM). The computational efficiency of solving the reduced random nonlinear heat conduction models can be enhanced by implementing these two technologies. The large coefficient of variation and the small coefficient of variation stochastic heat conduction problems, respectively, are addressed by the two non-intrusive statistical methods, i.e., the quasi-Monte Carlo method (QMCM) based on number theory and the modified stochastic perturbation method (MSPM). These two methods necessitate deterministic analysis and are easily integrated into the model reduction method. In four numerical instances, the selection of RBVs, the influence of the nonlinear term on the random temperature response, and the accuracy and efficiency of the two non-intrusive statistical moment methods are discussed. The numerical results highlight that the model reduction strategy based on the decoupling of thermal conductivity and GCM, in conjunction with the QMCM and the MSPM, enables the analysis of stochastic nonlinear transient heat conduction problems with a large coefficient of variation and a small coefficient of variation, respectively. • The research of stochastic nonlinear transient heat conduction problem (SNTHCP). • The application of non-intrusive statistical moment methods in SNTHCP. • The adoption of deterministic reduce basis vectors for Galerkin projection method. • An efficient model-order reduction scheme is proposed in this paper. [ABSTRACT FROM AUTHOR]

The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed, axial compressor. The flat-baffles with different span heights are used to simulate different distorted inflow cases. Compared with auto-correlation and root-mean-square analysis, cross-correlation analysis used to predict early stall warning does not depend on the distortion position. Hence, the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions. Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios, tip air injection was adopted as the actuator for adaptive feedback control. The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions. The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow. Thus, the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow, which frequently occurs in flight.

A sequentially coupled thermo-mechanical finite element model is used to simulate the friction stir welding process. Fracture mechanical models for the middle tension specimen and the eccentrically loaded single-edge crack tension specimen are established. Utilizing the residual stress intensity factor obtained by the fracture mechanical models, the crack-closure model and superposition method are adopted to predict the fatigue crack growth rates of the two specimens. The results indicate that the effect of the residual stress on the fatigue crack growth rate becomes obvious as the stress ratio decreases. Considering the residual stress, the fatigue life of the welded plate exhibits a dramatic decrease for the middle tension specimen, but a remarkable increase for the eccentrically loaded single-edge crack tension specimen. The fatigue life of the middle tension specimen is almost insensitive to the rotational speed, but that of the eccentrically loaded single-edge crack tension specimen increases with the increase in the rotational speed.