On-machine measurement method for dynamic stiffness of thin-walled workpieces

This paper proposes a novel measurement method for the dynamic stiffness of thin-walled workpieces. The proposed method is called the displacement sensorless piezoexcitation (DSPE) method. The DSPE method uses a piezoelectric shaker attached to a machine tool spindle. Sensor setup on workpieces is not required because workpiece displacement is estimated from the excitation force and input voltage to the shaker. A measurement instrument based on the DSPE method was developed. The measurement accuracy of the DSPE method was verified by comparing its measurement results to those of a conventional piezoexcitation method and impact tests. The experimental results demonstrate that the DSPE method is almost comparable to the conventional methods. Cutting experiments were conducted to analyze the workpiece compliance measured by the DSPE method and the vibration amplitude during cutting. The results demonstrate that the DSPE method can accurately evaluate the dynamic stiffness affecting vibration during the cutting process

Evaluation of on-machine measuring method for dynamic stiffness of thin-walled workpieces

8th CIRP Conference on High Performance Cutting (HPC 2018)Machining of thin-walled workpieces is a popular issue due to its static and dynamic displacements during machining. It is required to set machining conditions sufficiently considering the vibration characteristics of the workpiece. An automatic on-machine system to measure the dynamic stiffness of the workpiece enables a reliable and frequent measurement. In this study, an on-machine measurement device for workpiece dynamic stiffness is evaluated. The cause of the difference in natural frequency between the on-machine measurement method and impact test is investigated. The influence of the additional mass by a shaker and accelerometer on the natural frequency is investigated using the Rayleigh-Ritz method. A cutting test is conducted to verify whether appropriate cutting conditions can be set from the measurement results of the on-machine dynamic stiffness measurement. The natural frequency difference between the on-machine measurement method and impact test was caused by the additional mass by the contact of the piezoelectric actuator. When the additional mass is 5% or less of the workpiece equivalent mass, the difference in natural frequency was as small as 10 Hz or less. In the cutting test using the workpiece with the sufficiently large mass, the compliance between the on-machine measurement method and impact test was comparable. When the forced vibration was small, the stability limit was correctly estimated from the on-machine dynamic stiffness measurement

A giant subcutaneous leiomyosarcoma arising in the inguinal region

BACKGROUND: Subcutaneous leiomyosarcoma is a rare condition that accounts for 1% to 2% of all superficial soft tissue malignancies. Approximately 10% of cases arise in the trunk, although the extremities are the most commonly affected. CASE PRESENTATION: We report herein the case of a 31-year-old man with a subcutaneous leiomyosarcoma, measuring 124 × 105 mm, arising in the left inguinal region. A wide local excision (with a resection margin ≥ 20 mm) was performed. Histological examination of the resected specimen revealed a leiomyosarcoma with high cellularity and two mitoses per 10 high-power fields. The patient remains well with no evidence of disease 5 years and 8 months after the operation. CONCLUSION: This is the first reported case of subcutaneous leiomyosarcoma arising in the inguinal region and also one of the largest tumors reported. The experience of this case and a review of the English-language literature (PubMed, National Library of Medicine, Bethesda, MD, USA) suggest that a resection margin of ≥ 10 mm is recommended when excising this rare tumor

Inflammation-based scoring is a useful prognostic predictor of pulmonary resection for elderly patients with clinical stage I non-small-cell lung cancer

OBJECTIVES: The number of elderly lung cancer patients requiring surgery has been increasing due to the ageing society and less invasive perioperative procedures. Elderly people usually have various comorbidities, but there are few simple and objective tools that can be used to determine prognostic factors for elderly patients with clinical stage I non-small-cell lung cancer (NSCLC). The aim of this retrospective study was to evaluate the prognostic factors of surgically treated, over 80-year old patients with clinical stage I NSCLC. METHODS: The preoperative data of 97 over 80-year old patients with clinical stage I NSCLC were collected at Nagasaki University Hospital from 1990 to 2012. As prognostic factors, inflammation-based scoring systems, including the Glasgow Prognostic Score (GPS) determined by serum levels of C-reactive protein and albumin, the neutrophil lymphocyte ratio (NLR) and the platelet lymphocyte ratio (PLR) were evaluated, as well as other clinicopathological factors, including performance status, body mass index, carcinoembryonic antigen, Charlson comorbidity index and type of surgical procedure. RESULTS: The median age was 82 (range, 80-93) years. There were 62 (64.0%) clinical stage IA cases and 35 IB cases. Operations included 64 (66.0%) lobectomies, 15 segmentectomies and 18 wedge resections. The pathological stage was I in 76 (78.4%) patients, II in 12 (12.4%), III in 8 (8.2%) and IV in 1 (1.0%). Twelve (12.4%) patients underwent mediastinal lymph node dissection. Overall survival and disease-specific 5-year survival rates were 55.5 and 70.0%, respectively. The average GPS score was 0.4 (0-2). Diseasespecific 5-year survival was significantly longer with GPS 0 than with GPS 1-2. (74.2%, 53.7%, respectively, P = 0.03). Overall 5-year survival was significantly longer with GPS 0 than with GPS 1-2. (59.7%, 43.1%, respectively, P = 0.005). Both the NLR (median value = 1.9) and the PLR (median value = 117) were not correlated with disease-specific and overall 5-year survival. On multivariate analysis, pathological stage I (P = 0.01) and GPS 0 (P = 0.04, hazard ratio: 2.13, 95% confidence interval 1.036-4.393) were significant prognostic factors. CONCLUSIONS: The preoperative GPS appears to be a useful predictor of overall survival and could be a simple prognostic tool for elderly patients with clinical stage I NSCLC

Modulation of the mechanical properties of ventricular extracellular matrix hydrogels with a carbodiimide crosslinker and investigation of their cellular compatibility

Hydrogels made from the cardiac extracellular matrix (ECM) as two-dimensional (2D) or 3D cell-culture substrates have beneficial biochemical effects on the differentiation of stem cells into cardiomyocytes. The mechanical properties of the substrates that match those of the host tissues have been identified as critical biophysical cues for coaxing the tissue-specific differentiation of stem cells. The objectives of the present study are (1) to fabricate hydrogels comprising pure ventricular ECM (vECM), (2) to make the gels possess mechanical properties similar to those of the decellularized ventricular tissue, and (3) to evaluate the cellular compatibility of the hydrogels. In order to achieve these aims, (1) a simplified protocol was developed to produce vECM solution easily and rapidly, (2) N-(3-Dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDAC) was chosen to crosslink the hydrogels made from the vECM solution to enhance their mechanical properties and stabilize the microstructure of the gels, (3) rat embryonic fibroblasts or cardiomyocytes were cultured on these gels to determine the cellular compatibility of the gels. In particular, the nonlinearity and viscoelasticity of the gels were characterized quantitatively using a newly proposed nonlinear Kelvin model. The results showed that EDAC treatment allowed modulation of the mechanical properties of the gels to the same level as those of decellularized ventricular tissue in terms of the equilibrium elasticity and relaxation coefficient. Cell culture confirmed the cellular compatibility of the gels. Furthermore, an empirical relationship between the equilibrium elastic modulus of the gels and the vECM and EDAC concentrations was derived, which is important to tailor the mechanical properties of the gels. Finally, the influence of the mechanical properties of the gels on the behavior of cultured fibroblasts and cardiomyocytes was discussed