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On-demand metal droplet ejection is a critical technical branch in industrial electronics. Among them, high temperature and surface tension are the mainly limited factors affecting the single droplet ejection of hot-melt metal. To this end, this work proposed a waveform optimization scheme based on a piezoelectric micro-jet device (PMJD) actuated by a piezoelectric stack and a flexible hinge amplifier for liquid metal. The structure and operation principle of the PMJD is presented and analyzed. The numerical simulation model for hot-melt metal is established; the ejection mechanism and boundary condition of metal droplet are analyzed in detail by a direct fluid-thermal-structure interactions (FTSI) numerical method, which reveal two operation modes of metal droplet ejection under trapezoidal driving waveform. The driving waveform for the PMJD is designed and optimized to allow metal droplets to be ejected, and the variation of the initial velocity and shape of droplets are also analyzed based on the designed waveform. Furthermore, the critical value of satellite droplets generation with fracture of liquid bridge is discussed by simulation, and the optimized waveforms can also be used to suppress satellite droplets.

A valve-based piezoelectric pump operated by three bending transducers is proposed in this work. The major features of the proposed pump are self-priming and high pressure. The structure and operation principle of the proposed pump are presented and analyzed in detail. The output displacement of the transducer can be obtained by Timoshenko beam theory; on this basis, the flowrate and pressure models of the pump are established based on gap flow theory and extended Bernoulli equation. A prototype of the pump is fabricated and the experimental system is established. The results indicate that the maximum output flowrate is 58.6 mL/min under the frequency of 160 Hz; and the maximum output pressure is 28.7 kPa at the frequency of 180 Hz; and the maximum output power is 6 mW at the backpressure of 12.5 kPa. Besides, the self-priming of the pump is 10.7 kPa; thus, there is no need to fill the pump during working process, which can bring a convenience to the operation of the pump.

In this article, a piezoelectric active proportional regulation valve with high differential pressure is proposed based on a bending transducer. The output flowrate of the valve can be accurately controlled by a bending transducer. The configuration design and driving principle of the valve are presented and analyzed. The static analyses are performed to determine the structural parameters of the valve and deduce its transient overflow gap. On this basis, the overall flowrate model of the valve is established using the theory of circumferential flow and extended Bernoulli equation. The effects of differential pressure and driving voltage on output flowrate are clarified. A prototype of the valve is manufactured and the experimental setup is also established to evaluate the performances of the valve. The results indicate that the proportional regulation of the valve can be achieved by changing the driving voltage; the valve displacement and response time under no liquid-loading condition are 16.16 μ m and 340 μ s at the voltage of 300 Vp-p; the maximum output flowrate is 286.3 mL/min under the differential pressure of 344.75 kPa, and the leakage level is 0.11%; the maximum cut-off pressure of 275.8 kPa can be realized; the corresponding input power is 185 mW.

Based on the theory of matrix optics, the first-order properties of the zoom system of the three-element variable focal power devices were analyzed, and the control equation of the focal power based on the system magnification was obtained. Combined with the initial parameters of the three-element system and taking the minimum spherical aberration as the objective, the initial structure of the system was designed, the control function of the shape parameters of the lens was obtained, and the focal power and image quality were evaluated and calculated. Finally, the design example was compared and verified. The results show that the solution of the optimal value of the minimum spherical aberration is reliable. The starting point and method of the design provide a theoretical research reference for the further design of zoom system by using variable focal power devices.

Additional file 1: Supplementary Figures.

PurposeOur understanding of breast cancer in very young women (≤35 years old) remains limited. We aimed to assess the clinicopathological characteristics, molecular subtype, and treatment distribution and prognosis of these young patients compared with patients over 35 years.MethodsWe retrospectively analyzed non-metastatic female breast cancer cases treated at three Chinese academic hospitals between January 1, 2008, and December 31, 2018. Local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) were compared between different age groups and stratified with distinct molecular subtypes.ResultsA total of 11,671 women were eligible for the final analyses, and 1,207 women (10.3%) were ≤35 years at disease onset. Very young breast cancer women were more likely to be single or childless, have higher-grade disease, have more probability of lymphovascular invasion (LVI) in tumor and triple-negative subtype, and be treated by lumpectomy, chemotherapy especially more anthracycline- and paclitaxel-based chemotherapy, endocrine therapy plus ovarian function suppression (OFS), anti-HER2 therapy, and/or radiotherapy than older women (P < 0.05 for all). Very young women had the lowest 5-year LRFS and DFS among all age groups (P < 0.001 for all). When stratified by molecular subtype, very young women had the worst outcomes vs. women from the 35~50-year-old group or those from >50-year-old group for hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2−) subtype, including LRFS, DFS, and OS (P < 0.05 for all). In terms of LRFS and DFS, multivariate analyses showed similar results among the different age groups.ConclusionOur study demonstrated that very young women with breast cancer had higher-grade tumors, more probability of LVI in tumor, and more triple-negative subtype, when compared with older patients. They had less favorable survival outcomes, especially for patients with the HR+/HER2− subtype.

Supplemental Material, sj-pdf-2-arx-10.1177_17298814211053103 for A video inpainting method for unmanned vehicle based on fusion of time series optical flow information and spatial information by Rui Zhao, Hengyu Li, Jingyi Liu, Huayan Pu, Shaorong Xie and Jun Luo in International Journal of Advanced Robotic Systems

Supplemental Material, sj-pdf-1-arx-10.1177_17298814211053103 for A video inpainting method for unmanned vehicle based on fusion of time series optical flow information and spatial information by Rui Zhao, Hengyu Li, Jingyi Liu, Huayan Pu, Shaorong Xie and Jun Luo in International Journal of Advanced Robotic Systems

A novel heterogeneous catalyst, amorphous Cu0 on the carbon nanofibers was developed and characterized by means of several characterization techniques. The prepared Cu0 was investigated as a heterogeneous catalyst for N-arylation reaction. The results show it is an excellent catalyst with recyclability, high consistency and catalytic activity. After the catalyst was used for 5 cycles in the N-arylation reaction, amorphous Cu0 reunited into crystalline copper nanoparticles with different particle sizes and its good heterogeneity in the catalytic system was confirmed after the catalyst recovery.

The injection performance of the piezoelectric micro-jet is mainly determined by the acoustic characteristics created in the cavity by the vibration of the piezoelectric vibrator. As sensors are difficult to be placed into the cavity of the piezoelectric micro-jet, the inside acoustic characteristics are hard to be tested by experiments. Thus, an acoustic-structure coupling model is given, and simulation analyses are carried out in this paper to study a piezoelectric micro-jet used for lubricating. The suitable working frequency for getting better lubricating performance is obtained by the frequency response characteristics analyses. The driving mechanism is revealed by comparing with the injection results. The influences of excitations on the acoustic pressure at the nozzle part are analyzed, and the methods for adjusting the working performance are obtained. The acoustic structure coupling model and results are verified by comparing with the experiment results.

A resonant piezoelectric proportional valve for large flowrate regulation was proposed in this work. The large flowrate of the valve and its proportional regulation under high differential pressure were achieved using a bending sandwich actuator (BSA). First, the configuration and operation principle of the valve were depicted, and its structural parameters were determined by simulated analyses. Then, the theoretical analysis method was accomplished to predict the flowrate, and the direct fluid structure interaction simulation was used to validate the theoretical model. Ultimately, a prototype was fabricated and experimentally measured for the output performances. The results denoted that the output displacement of the BSA under the loaded condition was 91.69 μm when the resonant frequency and voltage were 2.19 kHz and 100 Vp-p; and the corresponding flowrates for the deionized water (DIW) and silicone oil (SLO) were 1.256 L/min and 0.221 L/min at 344.75 kPa. Besides, the cut-off pressures for the DIW and SLO were 289.59 kPa and 310.275 kPa under −300 V0-p; and the leakages were 0.5 mL/min and 0.2 mL/min under 344.75 kPa. This valve is expected to be applied to the cooling systems, hydraulic actuators.

The reliable obstacle detection is a challenging task in autonomous navigation of unmanned surface vehicles. In this paper, we present a novel real-time obstacles detection based on monocular vision which can effectively tell apart obstacles on the sea surface from complex background. The main innovation of this paper is to propose a water-boundary-line algorithm based on semantic segmentation and random sample consistency line fitting. And use a simple and effective saliency detection method based on background prior and foreground prior to detect obstacles under the water-boundary-line. Our method can efficiently and quickly obtain obstacle information from images captured by shipborne cameras, and it has the ability to process more than 33 frames/s.

Piezoelectric pumps have obtained considerable significance and have become the focus area of research for biomedicine, fuel supply, liquid cooling, chemistry and precision driving, etc. The advance direction of piezoelectric pumps integrates transfer devices into microfluidic systems to accomplish the requirement for accurate transfer of fluids. Various piezoelectric pumps have been emerged in recent decades, and the recent research and development have been brought out in the present review. This work highlights the development history and focuses particularly on the research of piezoelectric pumps in four aspects: configuration design, working mode, optimization and application, respectively. Firstly, some representative configurations of piezoelectric pumps including valve, chamber and piezoelectric vibrator are provided, and the performances are compared based on overall size, voltage, frequency, flowrate, pressure, flowrate density and pumping medium, etc. The advantages of piezoelectric pumps are discussed and the disadvantages are analyzed where appropriate. Secondly, two typical working modes and performance analyses of piezoelectric pumps including non-resonant and resonant modes are discussed. Thirdly, some optimization investigations and applications of piezoelectric pumps are summarized. Finally, the conclusions are given and the future development perspectives of piezoelectric pumps are discussed. The main contribution of this review is to give a synthetic understanding on piezoelectric pumps. This work also attempts to provide both a guidance for piezoelectric pump researchers on improving their output performances and a resource for those outside the field who wish to identify the best piezoelectric pump for a particular application.

A resonant piezoelectric micro-jet (RPMJ) using a longitudinal transducer (LT) is proposed for achieving high-speed jetting of high-viscosity liquid. The continuous droplets are realized by the pressure change of micro-jet element (MJE) which can be generated by the high frequency vibration of the LT. The RPMJ is designed and its driving principle is simulated to reveal the pressure change and the jetting status. The modal and harmonic response analyses are performed to determine the resonant frequency of the LT. The transient and two-phase coupling analyses are launched to optimize the parameters of the MJE; and the jetting performances under the various viscosities of silicone oils are analyzed. A prototype of the RPMJ is fabricated and its tested system is established. The jetting of the silicone oil with the viscosity of 150 cps is achieved under the voltage of 300 Vp-p and frequency of 19.4 kHz, and the average flowrate is about 0.07 ml/s. The maximum average flowrate can reach to 0.51 ml/s when the viscosity is 2 cps. In a word, the viscosity range of operable liquid has been broadened using the proposed RPMJ.

Piezoelectric micro-jet devices (PMJDs), also known as piezoelectric inkjet printing, are used to distribute the functional materials to form single or complex microstructures on a substrate. As one of the most promising technologies in the field of additive manufacturing in the 21st century, the PMJDs have received a lot of attentions from universities, enterprises and research institutes. In this review, the origin of the PMJDs is introduced and the data analyses of the PMJDs are also counted based on Web of Science database. Concretely, the fundamental actuation modes and structure configurations of the PMJDs are summarized firstly. Secondly, the analysis methods of the PMJDs are discussed. Thirdly, the challenges of the PMJDs are explicitly discussed. Fourthly, aiming at the current challenges, the schemes on improving the droplet uniformity and productivity of the PMJDs are discussed in detail. However, there are still many studies to be completed and optimized to solve the bottlenecks faced by the PMJDs. Finally, the applications of the PMJDs are described systematically. In general, this review is expected to be of interest to both seasoned researchers and practitioners in the PMJDs and those entering this field for the first time.

Background To evaluate the accuracy of sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in breast cancer patients with axillary lymph node (ALN) metastasis. Methods A total of 122 patients with operable breast cancer were enrolled in this single-center retrospective study. Eighty patients were clinically diagnosed with a positive axillary lymph node (ALN) via imaging or physical examination (including 66 patients with biopsy-proven metastasis). The other 42 cases had a clinically negative ALN. After four sessions of neoadjuvant chemotherapy, patients were assigned to an ALN-positive or -negative group. The identification rate (IR) and false negative rate (FNR) were determined in the ALN-negative group. Results ALN changed from positive to negative after NAC in 48 patients. Among them, 46 had at least one SLN resected (total IR = 95.8 %). Eight of the 46 SLN-negative patients had pathologically confirmed metastasis of at least one non-SLN (FNR = 36 %). Fifty-five of the 56 patients with a biopsy-proven negative ALN remained ALN negative. Furthermore, 54 of the 56 patients had at least one SLN resected (IR =98.2 %). Three SLN-negative patients of the 54 had at least one positive non-SLN (FNR = 10.7 %). Conclusions Due to its high FNR, post-NAC SLNB is not recommended for breast cancer patients with ALN metastasis confirmed by biopsy, though their ALN may become negative after NAC. However, for operable breast cancer with negative ALN, post-NAC SLNB is feasible if the ALN remains clinically negative after NAC. Trial registration Retrospective evaluation.

With the development of the robot industry, the requirements of the joint actuator are improved. The steering gear becomes the first choice of the joint actuator, which has the characteristics of a modular, high integration, Small volume. However, there are universal problems of the steering gear in the domestic market, that torque is too small and rotation angle range is only 120 degrees. This paper adopts the method of contrast analysis of the influence the steering performance of a series of parameters for optimization design of steering gear. Through the drive scheme design, structure design, precision analysis and engineering drawings to finish the design work. Harmonic reducer is used to realize the steering gear of high torque output function; The non contact magnetic encoder is chosen to detect the rotation angle and improve the positioning accuracy and expand the range of rotation angle; The three-loop control is used to improve the response speed and accuracy of the motor. This paper mainly introduces the present situation of domestic research and the design of each module, and gives the concrete scheme of mechanical structure, hardware circuit and software design.

Summary Background Treatment of extraordinarily large deep burns remains a huge clinical challenge. Case Report This article is a summary of our experience with the treatment of a patient with an extraordinarily large deep burn (99.5% TBSA and 23% fourth degree burn) by using the “microskin autografting and alloskin repeated grafting” method to close the deep burn wound because of scarcity of skin sources of the patient. Conclusions The patient has been observed for 2 years, and is able to face the reality of life peacefully with the support of his family.

The generation of animals lacking Smad proteins has made it possible to explore the contribution of the TGF-beta-Smad signaling to immune activity in vivo. And there have been related issues actively pursued by many laboratories. Here we report that, in contrast to the markedly enhanced inflammatory response, Smad3 gene knockout (Smad3(ex8/ex8)) mice paradoxically show suppressed hepatic acute phase response to the injury induced by lipopolysaccharide (LPS) compared with wild-type mice, characterized by significantly weaker reaction of several typical acute phase proteins in mRNA level. The increase of positive acute phase proteins, e.g. alpha1-acid glycoprotein (alpha1-AGP), haptoglobin (HP) and C-reaction protein (CRP), and the decrease of negative acute phase proteins, including albumin (ALB) and transferrin (TRF), were both repressed according to the expression in liver estimated by optimized RT-PCR. Smad3(ex8/ex8) mice also exhibited lower survival rate as stimulated by LPS, which was probably on account of the suppressed acute phase response. These data are, to our knowledge, the first to implicate Smad3 in specific pathways of acute phase response in the liver.

TSP (Traveling Salesman Problem, TSP) is a classic combinatorial optimization problem and nowadays it is a hot topic to find a high precision algorithm with short solving time. As its search space increases with the number of cities, it often requires a lot of computation time to find the optimal solution in a large space. So a new TSP solving algorithm is proposed based on an improved fruit fly optimization algorithm. Aiming at solving these shortcomings of standard fruit fly optimization algorithm, such as easily plunging into local optimal and low convergence-rate, mutation operator is introduced, which improves the diversity of the population and prevents premature. The strategy of adaptive variable step size is adopted, which increases search efficiency effectively. Finally, the improved fruit fly optimization algorithm is verified to be efficient, comparing with standard fruit fly optimization algorithm and particle swarm optimization algorithm benchmarked against TSPLIB.

To explore the risk factors relating to lower digestive tract haemorrhage in severe burns and summarise the experience in clinical diagnosis and treatment.General data of 103 patients with severe extensive burns (EBs) admitted to our burn centre in Shanghai between 1997 and 2009 were reviewed retrospectively. The risk factors relating to EB-complicated lower digestive tract haemorrhage were analysed systematically with respect to the clinical features and experiences in treatment, and prognosis.Of the 103 severe EBs, five developed lower digestive tract haemorrhage with an occurrence of 4.9%. Four of them were proved to have multiple mucosal erosions in caecum, colon and rectum, and the remaining one was proved rectal ulcerative haemorrhage. In comparison with upper digestive tract haemorrhage, lower digestive tract haemorrhage in the present group was characterised by a longer duration (median 4.0 days, interquartile range (IQR) 1.5-14.5 days vs. median 2.0 days (IQR 1.0-3.0 days), P0.05). Deep burns, especially fourth-degree burns, with complications of severe systemic infection, formed the main risk factors relating to lower digestive tract haemorrhage in severe EB patients.Severe EB-complicated lower digestive tract haemorrhage is a critical condition in burns, which usually have deep wounds with severe infection surfaces that are difficult to deal with. Enteroscopic haemostasis in controlling lower digestive tract haemorrhage is usually ineffective. Clinical experiences indicate that early management of the wound with effective preventive and therapeutive measures for infection control may be a good choice in the prevention and treatment of lower digestive tract haemorrhage leading to improvement in its prognosis.

Poly (ethylene-co-vinyl acetate) (EVA) is the major polymer used for photovoltaic (PV) modules encapsulation. Its degree of cross-linking (related to its gel content) is taken as a major quality reference. Differential Scanning Calorimetry (DSC) has been proven to be fast and effective but is to determine the gel content, however, destructive for the PV module. With the aim to develop a non-destructive quality assessment tool, a detailed discussion on the DSC thermogram of EVA PV encapsulant is presented here. A possible path towards a fast and non-destructive method for determing EVA gel content is proposed based on the DSC analysis.

A high-quality encapsulation process is crucial to ensuring the performance and long-term reliability of photovoltaic (PV) modules. In crystalline Si technology-based modules, poly (ethylene-co-vinyl acetate) (EVA) is the most widely used PV encapsulant. Its encapsulation process is usually performed in a flat-bed vacuum bag laminator. In certain types of laminators, cooling press can be applied to the module cooling process after the module encapsulation, leading to a much higher cooling rate (similar to 100 degrees C/min) than conventional natural cooling due to the application of water cooling circulation and mechanical pressure on the modules. In this work, the effect of the cooling press on the encapsulation properties of PV modules with EVA as the encapsulant are assessed on the aspects of residual stress in the modules, peeling strength between glass and EVA, and the resulting EVA gel content after encapsulation. The results show that the cooling press influences the encapsulation properties of PV modules. In particular by applying the cooling press after encapsulation, the residual normal stress in the Si solar cell in the encapsulated module after cooling can be reduced by as much as 22 +/- 2 to 27 +/- 3% depending on the EVA gel content, whereas the peeling strength between front glass and EVA is increased by similar to 10%. This work should help the further optimization of PV module encapsulation processes aimed at improving module encapsulation quality. Copyright (C) 2013 John Wiley & Sons, Ltd.

The recycling or re-use of failed c-Si PV modules could be a significant concern in the near future. The existing approaches for cell recovery can be improved both environmentally and economically friendly. Here we propose a novel double encapsulation module with an optical coupler (DEMOC) module design for convenient c-Si cell recovery. In this paper, the concept of DEMOC is illustrated. We successfully determine the materials and lamination recipes for single-cell re-usable mini-modules. The optical reflection and IV performance of DEMOC are measured and prove to surpass those of an earlier-proposed design without optical coupler. The cell recovery procedure of the DEMOC design is discussed at last.

Poly(ethylene-co-vinyl acetate) (EVA) is the primary polymer used for encapsulation of photovoltaic (PV) modules. Its degree of cross-linking (gel content) is taken as a major quality reference. The EVA gel content is normally measured by Soxhlet extraction and more recently also by Differential Scanning Calorimetry (DSC). The DSC method is proven here to be fast and effective but is, as the Soxhlet extraction method, destructive to the PV module. With the aim of developing a fast and non-destructive method to determine the gel content, a number of analytical techniques are presented. The most promising method is ultraviolet/visible/near-infrared (UV/Vis/NIR) optical transmission. The measured diffuse transmission reflects the EVA crystallite size, which is related to the EVA gel content. This opens the possibility to apply an in-line analysis of every PV module immediately after the lamination step and could significantly contribute to the process quality control that is needed in future high-throughput production lines of PV modules.

Appropriate encapsulation schemes are essential in protecting the active components of the photovoltaic (PV) module against weathering and to ensure long term reliability. For crystalline cells, Poly (ethylene-co-vinyl acetate) (EVA) is the most commonly used PV encapsulant. Additives like peroxides and silanes are formulated in EVA encapsulants to obtain the desired properties, e.g. the desired gel content value and sufficient adhesion after the encapsulation process etc. The identification and control of volatile organic compounds (VOCs) released by the polymeric encapsulant during PV module encapsulation is important for understanding and optimizing processes in order to enhance the encapsulation quality of the manufactured modules. Here we demonstrate how gas chromatography and mass spectrometry (GC-MS) techniques can be used to help understand the curing process, mainly by identifying the VOCs emanating from EVA under the effect of temperature and pressure. The results provide chemical insights into the EVA encapsulation process, which are valuable for further optimization of the PV module manufacturing process and evaluation on its environmental impact.