The effect of maximum normal impact load, absorbed energy and contact impulse on the impact craters volume/depth of DLC coating under repetitive impacts

Recently, the requirements for measuring dynamic responses have become severe and varied in many industrial and research applications such as material testing, model analysis and crash testing1). Surface degradation often occurs due to this dynamic response. This phenomenon also appears in the DLC coatings material. In this present work, a self-developed horizontal impact tester can provides this type of response, which gives an effect to the impact craters volume/depth of DLC coating

Raman Spectroscopy Study of Impacted DLC Coatings

Raman scattering is an excellent tool to characterize the structure of carbon atoms in diamond-like carbon (DLC). The study of DLC coatings in the sliding conditions has been conducted for a decade using Raman spectroscopy analysis. However, there is still insufficient information about how the structure of DLC coatings changes during repetitive impact. In this paper changes in the structure under 90o repetitive impact at a large number of cycles are presented

Deformation and wear map of DLC coating under cyclic impacts

Generally, the construction of transition maps follow two different approaches ; empirical and physical modelling. However, only empirical approach is used in this study. In this century, there is no development of deformation-wear transition map of the DC coating under cyclic impact loading. Therefore, the aim of this study is to propose a new deformation-wear transition map of DLC coating based on variations of maximum normal impact loads and impact cycles for future design purposes

Multiple rectal carcinoids with diffuse ganglioneuromatosis

BACKGROUND: Rectal carcinoids comprise only about 1% of all anorectal neoplasms. In addition, ganglioneuroma of the gastrointestinal tract is a rare tumor composed ganglion cells, nerve fibers, and supporting cells. Multiple carcinoid tumors with diffuse ganglioneuromatosis limited to the rectum are quite unusual. CASE PRESENTATION: A 69-year-old man was referred to us because of about 100 small submucosal rectal tumors. He underwent abdominoperineal resection. Pathology revealed carcinoid tumors for about 30 submucosal nodules and diffuse ganglioneuromotosis. To date (6 months later) he remains well with no recurrence. CONCLUSION: Although the optimal treatment for the multiple rectal carcinoids remains to be clearly established, it is believed that not all patients with multiple rectal carcinoids (measuring less than 1 cm in diameter) need to have a radical operation. However, the treatment plan for each case should be individualized and a careful follow-up is mandatory

Miniature Pneumatic Curling Rubber Actuator Generating Bidirectional Motion with One Air-Supply Tube

Soft actuators driven by pneumatic pressure are promising actuators for mechanical systems in medical, biological, agriculture, welfare fields and so on, because they can ensure high safety for fragile objects from their low mechanical impedance. In this study, a new rubber pneumatic actuator made from silicone rubber was developed. Composed of one chamber and one air-supply tube, it can generate curling motion in two directions by using positive and negative pneumatic pressure. The rubber actuator, for generating bidirectional motion, was designed to achieve an efficient shape by nonlinear finite element method analysis, and was fabricated by a molding and rubber bonding process using excimer light. The fabricated actuator was able to generate curling motion in two directions successfully. The displacement and force characteristics of the actuator were measured by using a motion capture system and a load cell. As an example application of the actuator, a robotic soft hand with three actuators was constructed and its effectiveness was confirmed by experiments

Long-term cultivation of colorectal carcinoma cells with anti-cancer drugs induces drug resistance and telomere elongation: an in vitro study

BACKGROUND: The role of telomerase activation in the expression and/or maintenance of drug resistance is not clearly understood. Therefore, we investigated the relationships, among the telomerase activity, telomere length and the expression of multidrug resistance genes in colorectal cancer cell lines cultivated with anti-cancer drugs. METHODS: LoVo and DLD-1 cells were continuously grown in the presence of both CDDP and 5-FU for up to 100 days. Cell proliferation, telomerase activity, telomere length and the expression of multidrug resistance genes were serially monitored as the PDL increased. RESULTS: The expression of multidrug resistance genes tended to increase as the PDL increased. However, an abnormal aneuploid clone was not detected as far as the cells were monitored by a DNA histogram analysis. Tumor cells showing resistance to anti-cancer drugs revealed a higher cell proliferation rate. The telomere length gradually increased with a progressive PDL. The telomerase activity reached a maximum level at 15 PDL in LoVo cells and at 27 PDL in DLD-1 cells. An increase in the mRNA expression of the telomerase components, especially in hTERT and in hTR, was observed at the same PDLs. CONCLUSIONS: These results suggest that a high telomerase activity and an elongation of telomeres both appear to help maintain and/or increase drug resistance in colorectal cancer cells. Cancer cells with long telomeres and a high proliferative activity may thus be able to better survive exposure to anti-cancer drugs. This is presumably due to an increased chromosome stability and a strong expression of both mdr-1 and MRP genes

The Cause of ‘Weak-Link’ Grain Boundary Behaviour in Polycrystalline Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 Superconductors

The detrimental effects of grain boundaries have long been considered responsible for the low critical current densities (J_c) in high temperature superconductors. In this paper, we apply the quantitative approach used to identify the cause of the 'weak-link' grain boundary behaviour in YBa2Cu3O7 [1], to the Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 materials that we have fabricated. Magnetic and transport measurements are used to characterise the grain and grain boundary properties of micro- and nanocrystalline material. Magnetisation measurements on all nanocrystalline materials show non-Bean-like behaviour and are consistent with surface pinning. Bi2Sr2CaCu2O8: Our microcrystalline material has very low grain boundary resistivity (ρ_GB), which is similar to that of the grains (ρ_G) such that ρ_GB≈ρ_G=2×〖10〗^(-5) Ωm (assuming a grain boundary thickness (d) of 1 nm) equivalent to an areal resistivity of ρ_G=2×〖10〗^(-14) Ωm^2. The transport J_c values are consistent with well-connected grains and very weak grain boundary pinning. However, unlike low temperature superconductors in which decreasing grain size increases the pinning along the grain boundary channels, any increase in pinning produced by making the grains in our Bi2Sr2CaCu2O8 materials nanocrystalline was completely offset by a decrease in the depairing current density of the grain boundaries caused by their high resistivity. We suggest a different approach to increasing J_c from that used in LTS materials, namely incorporating additional strong grain and grain boundary pinning sites in microcrystalline materials to produce high J_c values. Bi2Sr2Ca2Cu3O10: Both our micro- and nanocrystalline samples have ρ_GB/ρ_G of at least 10^3. This causes strong suppression of J_c across the grain boundaries, which explains the low transport J_c values we find experimentally. Our calculations show that low J_c in untextured polycrystalline Bi2Sr2Ca2Cu3O10 material is to be expected and the significant effort in the community in texturing samples and removing grain boundaries altogether is well-founded

Utility of preoperative dynamic magnetic resonance imaging of the pancreas in diagnosing tumor-forming pancreatitis that mimics pancreatic cancer: report of a case.

The differential diagnosis of pancreatic carcinoma and tumor-forming pancreatitis remains difficult, and this situation can cause serious problems because the management and prognosis of these two focal pancreatic masses are entirely different. We herein report a case of tumor-forming pancreatitis that mimics pancreatic carcinoma in an 80-year-old woman. Computed tomography showed a solid mass in the head of the pancreas, and endoscopic retrograde cholangiopancreatography showed a complete obstruction of the main pancreatic duct in the head of the pancreas. Dynamic contrastenhanced magnetic resonance imaging (MRI) demonstrated a time-signal intensity curve (TIC) with a slow rise to a peak (1 min after the administration of the contrast material), followed by a slow decline at the pancreatic mass, indicating a fibrotic pancreas. Under the diagnosis of tumor-forming pancreatitis, the patient underwent a segmental pancreatectomy instead of a pancreaticoduodenectomy. The histopathology of the pancreatic mass was chronic pancreatitis without malignancy. The pancreatic TIC obtained from dynamiccontrast MRI can be helpful to differentiate tumor-forming pancreatitis from pancreatic carcinoma and to avoid any unnecessary major pancreatic surgery