Microstructure evolution and enhanced fatigue behavior in the Mg-10Li-5Zn-0.5Er alloys micro-alloyed with Yb

In this paper,(0.2-1 wt%)Yb was added to improve the tensile properties and high-cycle fatigue behavior of the as-cast and as-extruded Mg-10Li-5Zn-0.5Er alloys.It is found that Yb mainly affects the mechanical properties of the alloy by changing the grain size,type and morphology of the second phases.Yb mainly exists in the formation of Mg_(2)Yb and Mg-Zn-Yb phases in the metallographic structure.With the addition of Yb,the grains are refined and these Yb-containing phases replace the large-sized MgLiZn phase to be enriched at the grain boundaries.While the addition of excess Yb reduces the number of small-sized MgLiZn phases in the grain,thus reducing the alloys’mechanical performance.After extrusion,the small-sized MgLiZn phase is refined and the number increases,which effectively improves the tensile and fatigue strength of the alloy.The fatigue strength is mainly affected by the number and morphology of the second phase,positively correlated with the strength.Balanced in grain size and number and size of second phases,the extruded alloy with 0.2Yb added exhibits excellent mechanical properties with the yield strength,ultimate tensile strength and elongation of 292 MPa,303 MPa and 11.7%,and an fatigue strength of 130 MPa.

A novel integrated microfluidic chip for on-demand electrostatic droplet charging and sorting

On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds,sample loss,and labor-intensive preparation procedures.Here,we demonstrate the development of a novel microfluidic chip that integrates droplet generation,on-demand electrostatic droplet charging,and high-throughput sorting.The charging electrode is a copper wire buried above the nozzle of the microchannel,and the deflecting electrode is the phosphate buffered saline in the microchannel,which greatly simplifies the structure and fabrication process of the chip.Moreover,this chip is capable of high-frequency droplet generation and sorting,with a frequency of 11.757 kHz in the drop state.The chip completes the selective charging process via electrostatic induction during droplet generation.On-demand charged microdroplets can arbitrarilymove to specific exit channels in a three-dimensional(3D)-deflected electric field,which can be controlled according to user requirements,and the flux of droplet deflection is thereby significantly enhanced.Furthermore,a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal.This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.

Efficient Carbon-Based CsPbBr_3 Inorganic Perovskite Solar Cells by Using Cu-Phthalocyanine as Hole Transport Material

Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.

Sensitivity Analysis of a Bioinspired Refractive Index Based Gas Sensor

It was found out that the change of refractive index of ambient gas can lead to obvious change of the color of Morpho butterfly＇s wing. Such phenomenon has been employed as a sensing principle for detecting gas. In the present study, Rigorous Coupled-Wave Analysis （RCWA） was described briefly, and the partial derivative of optical reflection efficiency with respect to the refractive index of ambient gas, i.e., sensitivity of the sensor, was derived based on RCWA. A bioinspired grating model was constructed by mimicking the nanostructure on the ground scale of Morpho didius butterfly＇s wing. The analytical sensitivity was verified and the effect of the grating shape on the reflection spectra and its sensitivity were discussed. The results show that by tuning shape parameters of the grating, we can obtain desired reflection spectra and sensitivity, which can be applied to the design of the bioinspired refractive index based gas sensor.

VMMAO-YOLO:an ultra-lightweight and scale-aware detector for real-time defect detection of avionics thermistor wire solder joints

The quality of the exposed avionics solder joints has a significant impact on the stable operation of the inorbit spacecrafts.Nevertheless,the previously reported inspection methods for multi-scale solder joint defects generally suffer low accuracy and slow detection speed.Herein,a novel real-time detector VMMAO-YOLO is demonstrated based on variable multi-scale concurrency and multi-depth aggregation network(VMMANet)backbone and“one-stop”global information gather-distribute(OS-GD)module.Combined with infrared thermography technology,it can achieve fast and high-precision detection of both internal and external solder joint defects.Specifically,VMMANet is designed for efficient multi-scale feature extraction,which mainly comprises variable multi-scale feature concurrency(VMC)and multi-depth feature aggregation-alignment(MAA)modules.VMC can extract multi-scale features via multiple fix-sized and deformable convolutions,while MAA can aggregate and align multi-depth features on the same order for feature inference.This allows the low-level features with more spatial details to be transmitted in depth-wise,enabling the deeper network to selectively utilize the preceding inference information.The VMMANet replaces inefficient highdensity deep convolution by increasing the width of intermediate feature levels,leading to a salient decline in parameters.The OS-GD is developed for efficacious feature extraction,aggregation and distribution,further enhancing the global information gather and deployment capability of the network.On a self-made solder joint image data set,the VMMAOYOLO achieves a mean average precision mAP@0.5 of 91.6%,surpassing all the mainstream YOLO-series models.Moreover,the VMMAO-YOLO has a body size of merely 19.3 MB and a detection speed up to 119 frame per second,far superior to the prevalent YOLO-series detectors.

Indium-doped perovskite-related cesium copper halide scintillator films for high-performance X-ray imaging

Scintillators are widely utilized in high-energy radiation detection in view of their high light yield and short fluorescence decay time.However,constrained by their current shortcomings,such as complex fabrication procedures,high temperature,and difficulty in the large scale,it is difficult to meet the increasing demand for costeffective,flexible,and environment-friendly X-ray detection using traditional scintillators.Perovskite-related cesium copper halide scintillators have recently received multitudinous research due to their tunable emission wavelength,high photoluminescence quantum yield(PLQY),and excellent optical properties.Herein,we demonstrated a facile solution-synthesis route for indium-doped all-inorganic cesium copper iodide(Cs_(3)Cu_(2)I_(5))powders and a high scintillation yield flexible film utilizing indium-doped Cs_(3)Cu_(2)I_(5)powders.The large area flexible films achieved a PLQY as high as 90.2%by appropriately adjusting the indium doping concentration,much higher than the undoped one(73.9%).Moreover,benefiting from low self-absorption and high PLQY,the Cs_(3)Cu_(2)I_(5):In films exhibited ultralow detection limit of 56.2 n Gy/s,high spatial resolution up to 11.3 lp/mm,and marvelous relative light output with strong stability,facilitating that Cs_(3)Cu_(2)I_(5):In films are excellent candidates for X-ray medical radiography.Our work provides an effective strategy for developing environment-friendly,low-cost,and efficient scintillator films,showing great potential in the application of highperformance X-ray imaging.

Microstructural evolution,mechanical properties and corrosion behavior of as-cast Mg-5Li-3Al-2Zn alloy with different Sn and Y addition

Influences of Sn and Y on the microstructure,mechanical properties,and corrosion behavior of as-cast Mg-5 Li-3 Al-2 Zn(LAZ532)alloy were investigated.The addition of Sn and Y refines grains and results in the formation of Mg2 Sn and Al2 Y phases,thus improving the mechanical properties of alloy by second phase strengthening and grain refinement strengthening.As-cast LAZ532 alloy shows typical filiform corrosion morphology,and the addition of Sn and Y does not change the corrosion mode of alloy.Ascast LAZ532-0.8 Sn-1.2 Y alloy shows excellent mechanical properties with yield strength of 166.2 MPa,ultimate tensile strength of 228.6 MPa and elongation of 14.8%,and exhibits the best corrosion resistance with the smallest corrosion current density and the lowest anodic dissolution rate.

Investigation of Fog Collection on Cactus-inspired Structures

We demonstrate the application of cactus-inspired structures for fog collection. The drop-on-cone system is modeled to analyze Gibbs free-energy gradients, equilibrium positions and motion of drops. Normalized free energy and free energy gra- dient are presented to characterize barrel and clam-shell drops, revealing the relations of the driving force and wettability to the half-apex angle of the cones. Small half-apex angle results in long collecting length and weak driving force. Thus it is important for fog collection to balance the driving force and collecting length with a suitable half-apex angle. Fog collection experiments on cactus-inspired structures are conducted for verification. Inflection points around 1.1° are observed, where the fog collection ability is mainly limited by the weak driving force when below the inflection points, while increases with the collecting length when above the inflection points. These indicate that the half-apex angle at the inflection point is a compromise between the driving force and collecting length, agreeing with the normalized functions. The results also prove that the hydrophilic cones are more suitable for fog collection with regard to condensation and driving force. Our research offers design guidance for efficient fog collection structure.

Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

We describe the formation of nested wrinkles created by the thermal mismatch between a narrow-band thin film and a compliant substrate.When a film is described as"narrow-band",it literally means that the film band width is much shorter than its length;more precisely,it means that the width is comparable with the wavelength of the wrinkles.A silicon mask was used during film sputtering to create narrow-band films on poly(dimethylsiloxane)substrate,thus creating regular boundaries to steer local stresses and control wrinkle morphology.Disordered nano-scale wrinkles were found nested within highly ordered micro-scale sinusoidal wrinkles.The formation of nested wrinkles was explained through the amplitude and wavelength saturation of nano-scale wrinkles.The disordered morphology of nano-scale wrinkles and the highly ordered morphology of microscale wrinkles were explained by using the boundary effect.

Analysis on annealing-induced stress of blind-via TSV using FEM

Copper-filled through silicon via （TSV） is a promising material owing to its application in high-density three-dimensional （3D） packaging. However, in TSV manufacturing, thermo-mechanical stress is induced during the annealing process, often causing reliability issues. In this paper, the finite element method is employed to investigate the impacts of via shape and SiO2 liner uniformity on the thermo-mechanical properties of copper-filled blind-via TSV after annealing. Top interface stress analysis on the TSV structure shows that the curvature of via openings releases stress concentration that leads to -60 MPa decrease of normal stresses, σxx and Cryy, in copper and -70 MPa decrease of σxx in silicon. Meanwhile, the vertical interface analysis shows that annealing-induced stress at the SiO2/Si interface depends heavily on SiO2 uniformity. By increasing the thickness of SiO2 linear, the stress at the vertical interface can be significantly reduced. Thus, process optimization to reduce the annealing-induced stress becomes feasible. The results of this study help us gain a better understanding of the thermo-mechanical behavior of the annealed TSV in 3D packaging. Keywords through silicon via （TSV）, annealing-induced stress, interface stress, plastic deformation, finite element method

Review on flexible perovskite photodetector:processing and

Next-generation optoelectronics should possess lightweight and flexible characteristics,thus conforming to various types of surfaces or human skins for portable and wearable applications.Flexible photodetectors as fundamental devices have been receiving increasing attention owing to their potential applications in artificial intelligence,aerospace industry,and wise information technology of 120,among which perovskite is a promising candidate as the light-harvesting material for its outstanding optical and electrical properties,remarkable mechanical flexibility,low-cost and low-temperature processing methods.To date,most of the reports have demonstrated the fabrication methods of the perovskite materials,materials engineering,applications in solar cells,light-emitting diodes,lasers,and photodetectors,strategies for device performance enhancement,few can be seen with a focus on the processing strategies of perovskite-based flexible photodetectors,which we will give a comprehensive summary,herein.To begin with,a brief introduction to the fabrication methods of perovskite(solution and vapor-based methods),device configurations(photovoltaic,photoconductor,and phototransistor),and performance parameters of the perovskite-based photodetectors are first arranged.Emphatically,processing strategies for photodetectors are presented following,including flexible substrates(i.e.,polymer,carbon cloth,fiber,paper,etc.),soft electrodes(i.e.,metal-based conductive networks,carbon-based conductive materials,and two-dimensional(2D)conductive materials,etc.),conformal encapsulation(single-layer and multilayer stacked encapsulation),low-dimensional perovskites(0D,1D,and 2D nanostructures),and elaborate device structures.Typical applications of perovskite-based flexible photodetectors such as optical communication,image sensing,and health monitoring are further exhibited to learn the flexible photodetectors on a deeper level.Challenges and future research directions of perovskite-based flexible photodetectors are proposed in the end.The purpose of this review is not only to shed light on the basic design principle of flexible photodetectors,but also to serve as the roadmap for further developments of flexible photodetectors and exploring their applications in the fields of industrial manufacturing,human life,and health care.

Real-time tool condition monitoring method based on in situ temperature measurement and artificial neural network in turning

Tool failures in machining processes often cause severe damages of workpieces and lead to large quantities of loss,making tool condition monitoring an important,urgent issue.However,problems such as practicability still remain in actual machining.Here,a real-time tool condition monitoring method integrated in an in situ fiber optic temperature measuring apparatus is proposed.A thermal simulation is conducted to investigate how the fluctuating cutting heats affect the measuring temperatures,and an intermittent cutting experiment is carried out,verifying that the apparatus can capture the rapid but slight temperature undulations.Fourier transform is carried out.The spectrum features are then selected and input into the artificial neural network for classification,and a caution is given if the tool is worn.A learning rate adaption algorithm is introduced,greatly reducing the dependence on initial parameters,making training convenient and flexible.The accuracy stays 90%and higher in variable argument processes.Furthermore,an application program with a graphical user interface is constructed to present real-time results,confirming the practicality.