Data-Driven Multi-Objective Optimization Approach to Loaded Meshing Transmission Performances for Aerospace Spiral Bevel Gears.

Loaded meshing transmission performance optimization has been an increasingly significant target for the design and manufacturing of aerospace spiral bevel gears with low noise and high strength. An innovative data-driven multi-objective optimization (MOO) method is proposed for the loaded meshing transmission performances of aerospace spiral bevel gears. Data-driven tooth surface modeling is first used to obtain a curvature analysis of loaded contact points. An innovative numerical loaded tooth contact analysis (NLTCA) is applied to develop the data-driven relationships of machine tool settings with respect to loaded meshing transmission performance evaluations. Moreover, the MOO function is solved by using an achievement function approach to accurate machine tool settings output, satisfying the prescribed requirements. Finally, numerical examples are given to verify the proposed methodology. The presented approach can serve as a powerful tool to optimize the loaded meshing transmission performances with higher computational accuracy and efficiency than the conventional methods.

Towards Understanding Subsurface Characteristics in Burn Process of Gear Profile Grinding.

In gear profile grinding, the grinding burn will greatly influence the anti-fatigue performance of gears. However, the influence of microstructure change caused by grinding burn on gear surface integrity is still unclear. In this paper, full-factor experiments of gear profile grinding are conducted and the grinding temperature is measured during the experiments. Furthermore, the tooth surface integrity including microstructure, residual stress, microhardness, and surface morphology is characterized. The relationship between grinding parameters, grinding burns and subsurface layer properties is analyzed by systematical test results. Radial grinding depths of more than 20 µm matched with wheel speeds below 30 m/s will result in severe grinding burns. The effect of grinding burns on the grain state mainly results in the breakdown of high strength martensite and the formation of inhomogeneous secondary tempered sorbite. The recovery and recrystallization of the microstructure of the tooth subsurface layer after grinding burns is the root cause of the substantial reduction in compressive residual stress and nano-hardness. The occurrence of grinding burns is mainly due to the unreasonable matching of process parameters rather than being influenced by a single grinding parameter alone. The risk of burn can be significantly reduced at greater wheel speeds and lower radial grinding depth. This study presents an insight into the mechanism of the effect of gear profile grinding burns on the surface integrity of the tooth flank.

Downregulation of miRNA-155-5p contributes to the adipogenic activity of 2-ethylhexyl diphenyl phosphate in 3T3-L1 preadipocytes.

2-Ethylhexyl diphenyl phosphate (EHDPP) is a commonly used organophosphorus flame retardant and food packaging material. Because of its high lipophilic and bioaccumulative properties, adipocytes are the primary target of EHDPP. However, the toxicity of EHDPP on preadipocytes and the potential mechanism have not been fully elucidated. MicroRNAs (miRNAs) are thought to be an important mediator that contribute to the toxicity of environmental contaminants. To identify the miRNAs specifically responsible for EHDPP exposure and their role in EGDPP's toxicity in preadipocytes, the adipogenic effects and miRNA expression profiling were performed on 3T3-L1 preadipocytes exposed to EHDPP. EHDPP at concentrations of 1-10 µM promoted adipocyte differentiation, as evidenced by lipid staining, triglyceride content, and expression of adipogenesis markers. MiRNA-seq analysis revealed that 7 differentially expressed miRNAs were recognized under EHDPP exposure, with miR-155-5p being the top down-regulated miRNA. Quantitative reverse transcription PCR (RT-qPCR) analysis showed that miR-155-5p level fell sharply during the first 2 days and continued to fall dose-dependently throughout the EHDPP exposure period. MiR-155-5p inhibition promotes adipocyte differentiation, whereas its overexpression counteracted EHDPP-induced adipogenesis. Luciferase reporter assay identified CCAAT/enhancer-binding protein beta (C/EBPß) as a target of miR-155-5p in 3T3-L1 preadipocytes in response to EHDPP. Taken together, EHDPP exposure down-regulated miR-155-5p, which then increased C/EBPß and peroxisome proliferator-activated receptor γ (PPARγ) expression and promoted adipogenesis in preadipocytes.

Simulation and Experimental Verification of Die Quenching Deformation of Aviation Carburized Face Gear.

The tooth width and length of face gear limit control the strength of face gear, and heat treatments are often used to improve the hardness and strength of face gear. However, heat treatments will often cause additional deformations, which will affect the dimensional accuracy of the face gear. In this paper, to effectively control the deformation and ensure the accuracy of the face gear, the finite element method was used to establish the calculation model of the face gear die quenching method, and thus, the influence of die on the gear quenching deformation was analyzed. Next, the accuracy of the calculation model was verified by the pressure quenching experiment. The results demonstrated that the inconsistent phase transformation between the surface and the center of the face gear was the key factor affecting the deformation due to the influence of the carbon content. Compared with die-less quenching, the inner hole-die can effectively limit the radial shrinkage deformation of the face gear. With the increase of the upper-die pressure, the axial and radial deformations of the face gear gradually became stable. In the actual production, the load of dies should be reasonably selected based on the gear accuracy requirements.

An Investigation of the Contact Fatigue Characteristics of an RV Reducer Crankshaft, Considering the Hardness Gradients and Initial Residual Stress.

The crankshaft is one of the core components of a Rotate Vector (RV) reducer. The fatigue life of the RV reducer is severely hindered by fatigue failure on the eccentric cylindrical surface of the crankshaft. The hardness gradients and residual stress in the crankshaft, associated with machining operations, exert an enormous impact on the rolling contact fatigue (RCF). In this work, a finite element method (FEM)-based three-dimensional elasto-plastic contact model is established to calculate the stress-strain field by taking hardness gradients and initial residual stress into account. The RCF characteristics of an RV reducer crankshaft is investigated by applying modified Fatemi-Socie (FS) multiaxial fatigue criterion. The results indicate that initial residual stress plays an influential role in the fatigue damage by altering the distribution of the maximum normal stress near the contact surface. The modified FS fatigue criterion could better consider the effect of initial residual stress and the shear stress, which significantly improves the prediction accuracy of the contact fatigue life model. The contact fatigue performance could be considerably improved by designing appropriate shot peening parameters to obtain optimized residual stress distribution. Therefore, the technique presented may serve as an important guideline for the anti-fatigue design of an RV reducer crankshaft.

Understanding Effects of Ultrasonic Vibration on Microstructure Evolution in Hot Forming Process via Cellular Automata Method.

Compared with traditional forming technology, ultrasonic vibration-assisted plastic forming technology can improve the forming conditions and obtain better surface quality of the workpiece. However, the mechanism and theory of ultrasonic action have not formed a unified understanding. In this paper, ultrasonic-assisted thermal forming technology is taken as the research object. Through experimental research combined with cellular automata methods, based on the dislocation density model, nucleation and growth model, and dynamic recrystallization growth rule, a theoretical model for microstructure simulation of the ultrasonic-assisted thermal forming process was established. By introducing the ultrasonic energy field into the thermal forming process and correcting thermal activation energy and dynamic recovery coefficient, the reasons for flow stress reduction of 9310 steel and the influence of temperature, strain rate, and vibration amplitude on recrystallization were analyzed from the microscopic scale. The results show that the introduction of ultrasonic vibration reduces the dislocation activation energy, promotes dynamic recrystallization behavior, and finally leads to the reduction of flow stress. With an increase in vibration amplitude, the average grain size decreases faster, the recrystallization volume fraction increases faster, the stress decreases larger, and the ultrasonic softening phenomenon becomes more obvious. Decreasing the strain rate will promote the occurrence of dynamic recrystallization, the volume fraction and average grain size of dynamic recrystallization will increase, and the true stress will decrease.

An Analytical and Experimental Study on Cutting Characteristics and Transient Cutting Force Modeling in Feed Directional Ultrasonic Vibration-Assisted Cutting of High Strength Alloys.

Ultrasonic vibration-assisted cutting (UVC) is progressively being used in machining as it can significantly promote the fabrication process. However, the ultrasonic vibration affecting the cutting process is still controversial. The full-transient cutting process is proposed in this study to analyze the affecting mechanism induced by ultrasonic vibration in the cutting process. This novel model is the first developed based on the fact that ultrasonic vibration would change mechanical behaviors and the cutting process. For example, the reduction of shear flowing stress in the primary shear zone and alteration of the shear angle in the UVC process. Then, considering those coupled effects, a novel model is proposed to determine the average and transient cutting forces. Here, insight and understanding into the physical phenomenon in UVC are provided. The effectiveness of the proposed model is verified by comparison with experimental results and analytical models available in the literature, with cutting parameters varying from macro to micro-scale. The results show that the ultrasonic vibration affects the cutting process in a complicated way, which is determined by transient characteristics, acoustic softening, thermal softening, plowing, and friction. Those effects on cutting performances in the UVC process under various cutting scenarios are investigated and discussed systematically. The average deviation of cutting forces between experiments and values predicted by the proposed model for Ti6Al4V, AISI 1045, and Al6063 is about 7%, 10.2%, and 11%, respectively. The deviation decreases with the increase of cutting speed in the machining of Ti6Al4V, which is different from the machining of other materials. This is contributed by the varied effect of ultrasonic vibration on the cutting process.

Rough Surface Characterization Parameter Set and Redundant Parameter Set for Surface Modeling and Performance Research.

Among the 26 roughness parameters described in ISO 25178 standard, the parameters used to characterize surface performance in characterization parameter set (CPS) lack scientificity and unity, resulting in application confusion. The current CPS comes from empirical selection or small sample experiments, thus featuring low generality. A new method for constructing CPS in rough surfaces is proposed to solve the above issues. Based on a data mining method, statistical theory, and roughness parameters definitions, the 26 roughness parameters are divided into CPS and redundant parameter sets (RPS) with the help of reconstructed surfaces and machining experiments, and the mapping relationships between CPS and RPS are established. The research shows that RPS accounts for 50%, and CPS, of great significance for surface performance, and has the ability to fully cover surface topography information. The birth of CPS provides an accurate parameter set for the subsequent study of different surface performance, and it provides more effective parameters for evaluating the workpiece surface performance from the same batch.

A Measurement Solution of Face Gears with 3D Optical Scanning.

Gears are usually measured by the contact metrology method in gear measuring centers or coordinate measuring machines. Recently, three-dimensional (3D) optical scanning, a non-contact metrology method, has been applied in the industry as an advanced measurement technology mainly due to its high efficiency. However, its applications to gears with complicated geometry, such as face gears, are still limited due to its relatively low accuracy and the void of related measurement solutions. In this work, an accurate measurement solution with 3D optical scanning is proposed for the tooth surface deviations of orthogonal face gears. First, point cloud collection is carried out by the 3D scanner. Furthermore, the measurement solution is implemented with a three-stage algorithm by aligning point clouds with the design model. Subsequently, 3D modeling is studied by numbering the points and reconstructing the real tooth surfaces. An example with a measurement experiment and loaded tooth contact analysis is given to show the validity of the proposed method.

Digital twin modeling for tooth surface grinding considering low-risk transmission performance of non-orthogonal aviation spiral bevel gears.

Low-risk transmission performance including elastic deformation, loaded contact pattern, load distribution and loaded transmission error is of paramount significance to the actual manufacturing for non-orthogonal aviation spiral bevel gears. The advanced digital twin technology is introduced into tooth flank grinding. A new digital twin modeling considering low-risk transmission performances is proposed. In the modeling, low-risk transmission performance driven simulation, sensitivity analysis and robust control are developed, respectively Firstly, data-driven tooth surface modeling is developed by simulating free-form tooth surface grinding including gear tilt method and pinion double helical method. With local geometric boundary setup meshing stiffness is determined by using local Rayleigh-Ritz solution. Then, to deal with the sensitivity of gear assembly, an improved tooth contact analysis (TCA) is developed. Moreover, numerical loaded tooth contact analysis (NLTCA) is performed to build a bridge between of low-risk performances and hypoid generator parameters. The low-risk transmission performance driven control model is established by using hypoid generator parameters modification. Finally, sensitivity analysis strategy-based robust control model is solved by using Levenberg-Marquardt method for accurate hypoid generator parameters having modification amount. The provided numerical instance can verify the proposed method.

An Efficient Approach to the Five-Axis Flank Milling of Non-Ferrous Spiral Bevel Gears.

Five-axis flank milling has been applied in industry as a relatively new method to cut spiral bevel gears (SBGs) for its flexibility, especially for the applications of small batches and repairs. However, it still has critical inferior aspects compared to the traditional manufacturing ways of SBGs: the efficiency is low, and the machining accuracy may not ensure the qualified meshing performances. To improve the efficiency, especially for cutting non-ferrous metals, this work proposes an approach to simultaneously cut the tooth surface and tooth bottom by a filleted cutter with only one pass. Meanwhile, the machining accuracy of the contact area is considered beforehand for the tool path optimization to ensure the meshing performances, which is further confirmed by FEM (finite element method). For the convenience of the FEM, the tooth surface points are calculated with an even distribution, and the calculation process is efficiently implemented with a closed-form solution. Based on the proposed method, the number (or total length) of the tool path is reduced, and the contact area is qualified. Both the simulation and cutting experiment are implemented to validate the proposed method.

ALKBH5 Inhibited Cell Proliferation and Sensitized Bladder Cancer Cells to Cisplatin by m6A-CK2α-Mediated Glycolysis.

N6-methyladenosine (m6A) is the most commonly occurring internal RNA modification to be found in eukaryotic mRNA and serves an important role in various physiological events. AlkB homolog 5 RNA demethylase (ALKBH5), an m6A demethylase, belongs to the AlkB family of dioxygenases and has been shown to specifically demethylate m6A in RNA, which is associated with a variety of tumors. However, its function in bladder cancer remains largely unclear. In the present study, we found that the expression of ALKBH5 was downregulated in bladder cancer tissues and cell lines. Low expression of ALKBH5 was correlated with the worse prognosis of bladder cancer patients. Furthermore, functional assays revealed that knockdown of ALKBH5 promoted bladder cancer cell proliferation, migration, invasion, and decreased cisplatin chemosensitivity in the 5637 and T24 bladder cancer cell lines in vivo and in vitro, whereas ALKBH5 overexpression led to the opposite results. Finally, ALKBH5 inhibited the progression and sensitized bladder cancer cells to cisplatin through a casein kinase 2 (CK2)α-mediated glycolysis pathway in an m6A-dependent manner. Taken together, these findings might provide fresh insights into bladder cancer therapy.

Electrical and Thermal and Self-Healing Properties of Graphene-Thermopolyurethane Flexible Conductive Films.

We fabricated graphene-thermopolyurethane (G-TPU) flexible conductive film by a blending method and systematically investigated the electrical, thermal and self-healing properties of the G-TPU flexible conductive film by infrared light and electricity. The experimental results demonstrate that the G-TPU composite films have good conductivity and thermal conductivity in the appropriate mass content of graphene in the composite film. The composite films have the good electro-thermal and infrared light thermal response performances and electro-thermal response performance is closely related to the mass content of graphene in the composite film, but the infrared light thermal response performance is not. The scratch on the composite film can be completely healed, using electricity or infrared light. The healing efficiency of the composite film healed using infrared light is higher than that of using the electricity, while the healing time of the composite film is shorter. Regardless of the self-healing method, the temperature of the self-healing is a very important factor. The self-healing conductive composite film still exhibits a good conductivity.

Simulations and error analysis of the CNC milling of a face gear tooth with given tool paths.

This data article gives the validation files to the article "CNC milling of face gears with a novel geometric analysis" [1]. The data is about the simulation and machining error analysis of the CNC milling of a face gear tooth with given tool paths. It includes four files. Three of them are simulation videos of the CNC milling process in VERICUT with a general view, partial view and enlarged view, respectively. The other one is the source file of the machining error analysis, and it has the design model of the face gear, the simulated machined model of the face gear, and machining error analysis according to the comparison of the design model and simulated machined model.

Disequilibrium in MMPs and the tissue inhibitor of metalloproteinases in different segments of the varicose great saphenous vein wall.

BACKGROUND: Varicose great saphenous veins (VGSVs) are a common disorder with a high incidence, but the pathogenesis is unclear. This study was designed to measure the changes in matrix metalloproteinases (MMPs) and the tissue inhibitor of metalloproteinases (TIMPs) in different segments from VGSV walls to determine the relationship between MMPs, TIMPs expression, and expansion of the venous wall. METHODS: Twenty-one VGSV and 12 normal great saphenous vein (GSV) specimens were collected. Venous walls in the two groups, expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 proteins, protein-positive expression ratios, mRNA expression, and protein content were determined by immunohistochemistry, PCR, and western blot. RESULTS: The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression in the upper, middle, and lower segments in the VGSV group were significantly higher than the corresponding regions in the GSV group, respectively. The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression, and protein concentrations in the lower segments in the VGSV group were also significantly higher than the upper and middle segments in the VGSV group and the corresponding regions in the GSV group, respectively. CONCLUSIONS: Under high hemodynamics, disequilibrium of MMPs and TIMPs from VGSVs exists within the upper, middle, and lower segments of VGSVs. These results suggested that MMPs and TIMPs participate in the process of venous wall remodeling and may be one of the mechanisms associated with the formation and development in varicose veins.

Genetic variants in a long noncoding RNA related to Sunitinib Resistance predict risk and survival of patients with renal cell carcinoma.

OBJECTIVE: LncARSR (lncRNA Activated in RCC with Sunitinib Resistance, ENST00000424980) is a newly identified lncRNA to promote the sunitinib resistance of renal cell carcinoma (RCC), which may contribute to tumorigenesis and progression. This study aimed to explore the association of lncARSR tagSNPs with the risk and prognosis of RCC. METHODS: In this study, a 2-stage case-control study was performed to evaluate the association between 2 tagging SNPs (rs1417080 and rs7859384) and RCC susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by unconditional logistic regression analyses. Different survival time was estimated by the Kaplan-Meier method and compared by the Log-rank test. Hazard ratios (HRs) and their 95% CIs were calculated to determine predictive factors by Cox proportion hazards model. RESULTS: When combing discovery and validation sets together, rs7859384 was determined to be significantly associated with the decreased RCC risk with all P < 0.05 in 4 models (co-dominant model, additive model, dominant model and recessive model). stratified analyses showed prominent risk effect of SNP rs7859384 GA/GG genotypes was found in clinical subgroups of stage I and stage II (P = 0.009, OR = 0.77, 95% CI = 0.64-0.94) and individuals with clear cell RCC (P = 0.014, OR = 0.79, 95% CI = 0.65-0.95). A protective effect of SNP rs7859384 GA/GG genotypes was observed among individuals with BMI > 24 (P = 0.025, OR = 0.74, 95% CI = 0.56-0.96), without hypertension (P = 0.037, OR = 0.79, 95% CI = 0.63-0.99), without family history of cancer (P = 0.048, OR = 0.83, 95% CI = 0.68-1.00). Survival analyses revealed individuals with GA/GG genotypes had higher survival rate compared with the corresponding AA wild genotypes in the dominant model (log-rank P = 0.005, adjusted HR = 0.34, 95% CI = 0.16-0.73). CONCLUSION: This study suggests that rs7859384 of lncARSR was associated with RCC susceptibility and may act as a prognostic biomarker for patients with RCC.

Study on contact performance of ultrasonic-assisted grinding surface.

The contact performance of ultrasonic-assisted grinding surface is studied in this paper. An improved simplified model of rough surface profile is proposed to find the microscopic feature parameters, such as the curvature radius of the asperity, which are suitable for contact analysis and calculation. Then a more accurate rough surface contact analysis model is obtained by combining the classical ZMC contact model. Based on the contact analysis model, the contact mechanism of ultrasonic-assisted grinding surface is studied. The contact stiffness and local maximum contact pressure of the surfaces under different cutting depths and ultrasonic amplitudes are calculated, and the correlation rule between the parameters of ultrasonic-assisted grinding and the contact performance of the machined surface is obtained: (1) With the increase of the cutting depth, the surface roughness of the workpiece increases; under the same load, the contact stiffness decreases and the maximum local contact pressure increases. (2) With the increase of the ultrasonic amplitude, the surface roughness of the workpiece first decreases and then increases. Under the same load, the contact stiffness increases first and then decreases, while the maximum local contact pressure resents an opposite variation trend. Under the experimental conditions, the surface contact performance of the workpiece is the best when the ultrasonic amplitude is 4 µm. Additionally, the contact performance of the ultrasonic-assisted grinding surface and the conventional grinding surface is compared: (1) When the ultrasonic amplitude is 4 µm, the surface roughness of the workpiece is at least 24% lower than that of the conventional grinding surface. (2) Under the same load, the surface contact stiffness of the ultrasonic-assisted grinding surface is increased by at least 68%, and the maximum local contact pressure is reduced by at least 17%. It is found that the interference motion of abrasive particles in the ultrasonic-assisted grinding process makes the surface height distribution more concentrated and the density of asperity increased, which results in a better contact performance compared with the conventional grinding surface.

Chloroquine Enhances the Radiosensitivity of Bladder Cancer Cells by Inhibiting Autophagy and Activating Apoptosis.

BACKGROUND/AIMS: Chloroquine was formerly used as an anti-malarial agent drug but has now been proven to be useful for various diseases. This study aimed to investigate the radiosensitizing effect of chloroquine in bladder cancer, with an emphasis on autophagy inhibition and apoptosis induction. METHODS: Bladder cancer cell lines were irradiated with or without chloroquine. Cell proliferation was determined by a Cell Counting Kit 8 assay. The radiosensitization effect of chloroquine was evaluated by clonogenic survival and progression of xenograft tumors. Cell apoptosis was detected by flow cytometry and western blot. Radiation-induced DNA double strand break was measured by the staining of γ-H2AX. In addition, autophagy was detected by western blot, immunofluorescence staining, and electron microscopy. RESULTS: The treatment with chloroquine alone inhibited the proliferation of bladder cancer cells in a dose-dependent manner. Low cytotoxic concentrations of chloroquine enhanced the radiation sensitivity of bladder cancer cells with a sensitization enhancement ratio of 1.53 and 1.40. Chloroquine also obviously weakened the repair of radiation-induced DNA damage. A combination of radiation and chloroquine enhanced the apoptosis rate of EJ and T24 cells and down-regulated the expression of Bcl-2 while up-regulating the expression of caspase-3. Additionally, the relevant markers of autophagy were obviously increased in the combined group, meaning that chloroquine inhibited autophagy induced by irradiation. Furthermore, subcutaneous xenograft tumors displayed that the combination of radiation and chloroquine could impede tumorigenesis in vivo. CONCLUSION: In summary, these results provided support that by inhibiting autophagy and activating apoptosis, chloroquine might be a potentially promising radiosensitizer in the radiation therapy of bladder cancer.

MiR-200c promotes bladder cancer cell migration and invasion by directly targeting RECK.

BACKGROUND: Increasing evidence suggests that the dysregulation of certain microRNAs plays an important role in tumorigenesis and metastasis. MiR-200c exhibits a disordered expression in many tumors and presents dual roles in bladder cancer (BC). Therefore, the definite role of miR-200c in BC needs to be investigated further. MATERIALS AND METHODS: Quantitative reverse transcription polymerase chain reaction was used to assess miR-200c expression. Cell invasion and migration were evaluated using wound healing and transwell assays. The luciferase reporter assay was used to identify the direct target of miR-200c. The expression of reversion-inducing cysteine-rich protein with kazal motifs (RECK) in BC tissues and adjacent nontumor tissues, as well as in BC cell lines, was detected through quantitative reverse transcription polymerase chain reaction, Western blot assay, and immunohistochemistry. RESULTS: The miR-200c expression was significantly upregulated in the BC tissues compared with the adjacent nontumor tissues. The downregulation of miR-200c significantly inhibited cell migration and invasion in the BC cell lines. The luciferase reporter assay showed that RECK was a direct target of miR-200c. The knockdown of RECK in the BC cell lines treated with anti-miR-200c elevated the previously attenuated cell migration and invasion. CONCLUSION: Our findings indicated that miR-200c functions as oncogenes in BC and may provide a novel therapeutic strategy for the treatment of BC.