A design method of high-compatibility horn for broad-bandwidth transducer.

Broad-bandwidth transducers are one of the main areas of focus for the development of power ultrasonic systems, which address the issues that the contactless transformer system cannot track transducer frequency and narrowband transducers are not compatible with different tools. This paper aims to investigate the potential capabilities of broad-bandwidth transducers in terms of compatibility with different horns and to propose a design method for highly compatible tools. The frequency equation of horn is nondimensionalized to calculate relative frequency errors δ. The effects of shape, dimensionless size, and order number on δ are investigated based on the equation. A compatibility range is proposed, and the relationship between it and the required relative bandwidth of the transducer is investigated. Various horns were designed, and the corresponding simulations, impedance measurements, and resonance experiments were conducted to explore the effects of these factors on δ, amplitude, and the quality factor Q. These experiments also verified the feasibility of using a broad-bandwidth transducer that is compatible with different tools. Finally, the application scenarios of the three horns are summarized based on a comparison of their matching ability, amplitude, operational stability, and compatibility range.

Mask-Point: Automatic 3D Surface Defects Detection Network for Fiber-Reinforced Resin Matrix Composites.

Surface defects of fiber-reinforced resin matrix composites (FRRMCs) adversely affect their appearance and performance. To accurately and efficiently detect the three-dimensional (3D) surface defects of FRRMCs, a novel lightweight and two-stage semantic segmentation network, i.e., Mask-Point, is proposed. Stage 1 of Mask-Point is the multi-head 3D region proposal extractors (RPEs), generating several 3D regions of interest (ROIs). Stage 2 is the 3D aggregation stage composed of the shared classifier, shared filter, and non-maximum suppression (NMS). The two stages work together to detect the surface defects. To evaluate the performance of Mask-Point, a new 3D surface defects dataset of FRRMCs containing about 120 million points is produced. Training and test experiments show that the accuracy and the mean intersection of union (mIoU) increase as the number of different 3D RPEs increases in Stage 1, but the inference speed becomes slower when the number of different 3D RPEs increases. The best accuracy, mIoU, and inference speed of the Mask-Point model could reach 0.9997, 0.9402, and 320,000 points/s, respectively. Moreover, comparison experiments also show that Mask-Point offers relatively the best segmentation performance compared with several other typical 3D semantic segmentation networks. The mIoU of Mask-Point is about 30% ahead of the sub-optimal 3D semantic segmentation network PointNet. In addition, a distributed surface defects detection system based on Mask-Point is developed. The system is applied to scan real FRRMC products and detect their surface defects, and it achieves the relatively best detection performance in competition with skilled human workers. The above experiments demonstrate that the proposed Mask-Point could accurately and efficiently detect 3D surface defects of FRRMCs, and the Mask-Point also provides a new potential solution for the 3D surface defects detection of other similar materials.

Study on Lubrication and Friction Reduction Properties of ZIF-8 Nanoparticles as Si3N4 Ceramic Water Lubrication Additives.

Ceramics can achieve superlubricity under water lubrication; however, their running-in period is long and application is rather limited by wear limit. Thus, zeolite imidazole ester skeleton (ZIF), an important branch of metal organic framework materials (MOFs), is expected to improve the tribological properties of lubricants and associated additives. As such, it has broad application prospects within the field. In this paper, ZIF-8 nanoparticles of varying concentrations were prepared and linked with amino functional groups. Specimens were used in silicon nitride self-matching pairs and their tribological properties were observed. After the experiment, friction surfaces were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and Fourier transform infrared radiation (FTIR). The experimental results have shown that ZIF-8 nanoparticles greatly reduced both friction and wear. Comprehensively considering running-in time, average COF during the whole process and smooth friction period COF, optimal performance was obtained for the ZIF-8 nanoparticle solution concentration of 1wt%. Furthermore, it was concluded that the lubrication properties of amino-modified ZIF-8 nanoparticles are significantly better compared to that of the unmodified ZIF-8. The anti-friction mechanism of ZIF-8 as a ceramic water lubrication additive was mainly through the filling and forming of nanoparticle film on the ceramic surface.

Dependency of the structure of a water layer sandwiched by silicon carbide on shear speed and temperature.

As a third-generation semiconductor, silicon carbide power devices are expected to be superior to those made of silicon because of their high voltage resistance, low loss, and high efficiency. So understanding the technology for polishing wafers of silicon carbide is important, which includes studying the structure of the liquid on the surface of silicon carbide. Using molecular dynamics based on Lennard-Jones field, the structure of a water film contained within two silicon carbide (〈001〉 and 〈110〉) walls was analyzed, and found that layers of water appear and change depending on the distance between the two walls. When a double-layer water structure forms, it is affected by the temperature and shear velocity. The conclusion is that when the temperature increases or the shear velocity increases, the double-layer water structure easily transforms into a single-layer water structure, and the pressure between the two solid surfaces gradually falls and may even become negative. This phenomenon significantly depends on the distance between the two silicon carbide walls.

Effects of the surface processing on the tribological performance of C/SiCs under dry friction.

A new friction counterpart for carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiCs) and zirconia (ZrO2) toughened by magnesia ceramics is proposed. The effects of the C/SiC surface processing parameters friction on the tribological performance are investigated under dry friction and ambient temperature conditions. The wear tests are carried out using the pin-on-disc friction method. Scanning electron microscopy (SEM) on an instrument equipped with an energy dispersive spectroscopy (EDS) is used to observe the surfaces of the pins and discs before and after the application of friction to reveal the wear mechanism. The results show that surface processing influenced the tribological properties of C/SiC significantly. When the pressure is 30 N, the speed is 0.5 m/s, and the C/SiC surface is ground using 1500# sandpaper, the counterpart tribological performance is the best among the samples considered herein. It is found that the retention ability of the counterparts influenced the tribology performance significantly.

A 4-year field measurement of N2O emissions from a maize-wheat rotation system as influenced by partial organic substitution for synthetic fertilizer.

Soil N2O emissions depend on the status of stoichiometric balance between organic C and inorganic N. As a beneficial management practice to sustain soil fertility and crop productivity, partial substitution of organic fertilizers (OFs) for synthetic fertilizers (SFs) can directly affect this balance status and regulate N2O emissions. However, no multi-year field studies of N2O emissions under different ratios of OFS to SFs have been performed. We conducted a 4-year experiment to measure N2O emissions in a maize-wheat rotation in central China. Six treatments were included: total SF (TS), total OF, no N fertilizer, and ratios of to SF with 1: 2 (LO), 1: 1 (MO), and 2: 1 (HO), based on N content. Two incubation experiments were performed to further interpret the field data. In the first year, cumulative N2O emissions (kg N ha-1) in LO, MO, and HO were 4.59, 4.68, and 3.59, respectively, significantly lower than in TS (6.67). However, from the second year onwards, organic substitution did not reduce N2O emissions and even significantly enhanced them in the fourth year relative to TS. Soil respiration under OF-amended soils increased over the course of the experiment. From the second year onwards, there was no marked difference in mineral N concentrations between OF- and SF-amended soils. OF caused a drop in soil pH. Cumulative N2O was negatively correlated with pH. Long-term organic substitution enhanced N2O emissions produced via denitrification rather than nitrification and resulted in higher temperature sensitivity of N2O emissions than TS. The enhanced N2O emissions from the OF-treated soils were mainly attributable to accelerated OF decomposition, increased denitrification-N2O emissions, and lessened N2O reduction due to lower pH and greater NO3-. These results indicate that OF substitution can reduce N2O emissions in the first year, but in the long-term it can increase emissions, especially as soils warm.

[Comparison of Short-term Outcomes of Lung Segmentectomy by Robotic-assisted and Video-assisted Thoracoscopic Surgery].

BACKGROUND: Lung segmentectomy is increasingly used to resect lung nodules. Video-assisted thoracic surgery (VATS) is widely chosen to performing lung segmentectomy, while robotic assisted thoracoscopic (RATS) was also one useful and practical method. There article was intended to compared the short-time outcomes of RATS and VATS in lung segmentectomy. METHODS: The patients with lung nodules underwent segmentectomy by either RATS or VATS from January 2016 to April 2017 were studied. Baseline characteristics and short-time outcomes (dissected lymph nodes, postoperative duration of drainage, postoperative hospital stay, incidence of pro-longed air leak, atrial fibrillation and pneumonia) were compared. RESULTS: 166 patients were included in this study: 81 patients underwent RATS segmentectomy while 85 underwent VATS segmentectomy. The number of lymph nodes dissected in RATS group was more than in VATS group ï¼»(13.07±5.08) vs (10.81±5.74), P=0.010ï¼½. The incidence of some postoperative complications such as pro-longed air leak, atrial fibrillation was not significant different between the two approaches. CONCLUSIONS: Compared with VATS, RATS has similar safety and operability, and the number of lymphadenectomy is significantly more than that of VATS.

Excellent Water Lubrication Additives for Silicon Nitride To Achieve Superlubricity under Extreme Conditions.

Superlubricity has been recognized as the future of tribology. However, it is hard to achieve superlubricity under extreme conditions such as a high load and low sliding speed on the macroscale. In this paper, a remarkable synergetic lubricating effect between nanoparticles and silicon nitride (Si3N4) is demonstrated; this effect helps water-lubricated Si3N4 achieve superlubricity under extreme conditions successfully. Different kinds of hairy silica nanoparticles were prepared, dispersed into water, and characterized using a variety of methods. The tribological properties of water-lubricated Si3N4 with nanoparticle additives were tested using a ball-on-disk tribometer under different loads and sliding speeds. The coefficient of friction and wear scar diameter were measured and analyzed. Both the nanoparticle size and surface functional groups have a significant influence on the tribological properties of water-lubricated Si3N4. Amino-modified silica nanoparticles reduce the friction coefficient of water-lubricated Si3N4 by 82.9% under 60 N, compared with that achieved using deionized water, and induce superlubricity after the running-in process. Silica nanoparticles effectively form a homogenous film with silica gel on the worn surface under a high load and thus reduce the wear and maintain the superlubricity under extreme conditions.

Robotic Bronchial Sleeve Lobectomy for Central Lung Tumors: Technique and Outcome.

BACKGROUND: The use of the surgical robot for standard lobectomy has widely spread worldwide. However there are relatively few studies of robotic bronchial sleeve lobectomy for central lung tumors. METHODS: We retrospectively evaluated 67 consecutive patients who underwent robotic bronchial sleeve lobectomy, a procedure without pulmonary vessel end-to-end anastomosis, performed by a single surgeon between October 2014 and March 2018. A half-continuous suture technique with two Prolene (Ethicon, Inc, Somerville, NJ) sutures for bronchial anastomosis was applied. The operative techniques and outcomes were analyzed. RESULTS: Complete resection was achieved in all patients undergoing different types of robotic bronchial sleeve lobectomy. There were no conversions to thoracotomy. The mean total surgical duration was 166.5 minutes (range, 78-286), total bronchial anastomosis time was 20.8 minutes (range, 10-44), estimated blood loss was 98.8 mL (range, 20-300), and postoperative hospital stay was 6.8 days (range, 4-13). No patient died within 90 days after surgery. The postoperative morbidity rate was 20.9%. Multivariate analysis showed that preoperative comorbidity, older age, and surgeon's early experience were risk factors for postoperative morbidity. CONCLUSIONS: Robotic bronchial sleeve lobectomy and the novel anastomotic technique are both feasible and safe for carefully selected patients.

[Difference of Lung Function Retention after Segmentectomy and Lobectomy].

In recent years, the incidence and detection rate of lung cancer have gradually increased, and segmentectomy has been increasingly used to treat early non-small cell lung cancer. Some scholars believe that segmentectomy is more conducive to the preservation of postoperative lung function than lobectomy. Some studies have found that the two surgical methods have little difference in postoperative cost retention. This article deals with segmentectomy and lobectomy. A review of related studies on postoperative pulmonary function changes.
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Circ-ZKSCAN1 regulates FAM83A expression and inactivates MAPK signaling by targeting miR-330-5p to promote non-small cell lung cancer progression.

BACKGROUND: Circular RNAs (circRNAs) belong to a new type of endogenous non-coding RNA and plays a key role in carcinogenesis. Circ-ZKSCAN1 (hsa_circ_0001727) has been proven to be a tumor-dependent circRNA. However, its role in non-small cell lung cancer (NSCLC) has been underreported. METHODS: The expression patterns of circ-ZKSCAN1 were determined using qRT-PCR in NSCLC samples and cell lines. Cell proliferation was examined utilizing the CCK-8 assay. Cell migration and invasion were evaluated using the Transwell assay. The combination of circ-ZKSCAN1 and miR-330-5p in NSCLC cells was analyzed by RNA pull-down and luciferase reporter assay. We used the bioinformatics software circbank, CircInteractome, TargetScan and Miranda to predict circRNA-miRNA and miRNA-mRNA interactions. RESULTS: Our results showed that circ-ZKSCAN1 was significantly up-regulated in NSCLC, closely related to malignant characteristics and poor prognosis, and clinically related to tumor size and clinical stage. Subsequent experiments showed that circ-ZKSCAN1 could inhibit the growth of NSCLC cells in vitro and in vivo. Importantly, circ-ZKSCAN1 can act as a sponge of carcinogenic miR-330-5p to increase the expression of FAM83A, resulting in the inhibition of MAPK signal transduction pathway, thus promoting the progress of NSCLC. Interestingly, the increase in FAM83A expression caused by circ-ZKSCAN1 overexpression could in turn promote the expression of circ-ZKSCAN1. CONCLUSIONS: Circ-ZKSCAN1 is a key positive regulator of NSCLC, and clarifies the potential molecular mechanism of the new circ-ZKSCAN1/miR-330-5p/FAM83A feedback loop in promoting the progress of NSCLC.

The flow characteristics of solid particles used as additives for lubricants in the point contact area.

Solid nanoparticles have been applied as anti-wear and friction reduction additives for lubricants. In this paper, the flow characteristics of solid particles used as additives for lubricants were studied. A flow field visualizer based on high speed photography was developed. The particle trajectories in the point contact area were recorded using the flow field visualizer and were compared with the particle trajectories simulated using COMSOL. The results were analyzed and compared with tribological test results. It was found that the experimental results matched well with the simulation results, and the speed of the particles decreased by 60% at the inlet and outlet zones of the contact area. Solid particles were found to experience an unsteady flow in both the inlet and outlet zones and this would contribute to particle sedimentation in those areas, which matches well with the findings of the tribology test, which showed that more particles sedimented in those two areas.

Bifunctional hairy silica nanoparticles as high-performance additives for lubricant.

Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands.