Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.

The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization.

[Isolation, purification, and functional evaluation of human pancreatic islet].

OBJECTIVE: To isolate and purify human islet according to the method established by Ricordi and to evaluate the function and safety of these isolated human islets. METHODS: Six pancreases were obtained from human corpses. The islets were isolated by liberase digestion and purificated by Ficoll density gradient centrifugation. The numbers, purity and vitality of the islets were analyzed. The various endocrine cell composition and distribution of the islets were checked by immunofluorescence staining. The glucose-induced insulin secretion was detected by chemiluminescence method. The isolated islets were transplanted under the left renal capsules of 10 streptozocin-induced diabetic nude mice. Twenty days later the left kidneys with transplanted islets of 2 mice with normal blood sugar were resected, and then blood sugar level was observed. An isolated human islet was suspended in RPMI-1066 culture medium for 72 h, then culture of pathogenic micro-organisms, endotoxin and procoagulant activity were detected so as to evaluate the security of the islet products. RESULTS: The mean number of the isolated islets was (229 000 +/- 31 000) islet equivalents (IEQs)/pancreas or (4970 +/- 1620) IEQs/g pancreatic tissue, the mean purity was (59.0 +/- 8.9)%, and the mean vitality was (89 +/- 3)% for the purified islets. Immunofluorescence staining showed that there were 4 types of endocrine cells normally distributed in the islets. The mean insulin stimulation index was 8.1 +/- 4.0 (3.8 - 10.2). The glycemia found in the diabetic nude mice decreased to normal levels from the third day after islet transplantation and maintained normal for over 30 days. The parameters of security in these islet products were under the standard scope. CONCLUSION: Human islets obtained according to Ricordi's method reach the standard for clinical islet transplantation in number, purity, vitality, function, and security.

Melatonin suppresses autoxidation and hydrogen peroxide-induced lipid peroxidation in monkey brain homogenate.

OBJECTIVES: Melatonin, the major secretory product of the pineal gland, is known as an effective antioxidant and neuroprotector. Its neuroprotective actions and mechanisms have been documented in a variety of rodent brain models. However, little is known of melatonin's antioxidative capacity in the brain of primates. Herein, we investigated whether melatonin would suppress autoxidation and exogenous hydrogen peroxide-induced lipid peroxidation in monkey cerebral cortical homogenates. MATERIALS AND METHODS: The monkey brain was dissected during routine autopsy and immediately frozen at -80 degrees C until the experiment. A sample of cerebral cortex (50 mg) was homogenized in 1 ml ice cold phosphate buffer (20 mM, pH 7.4) at 0-4 degrees C. Four different treatments of cerebral cortical homogenates were performed: 1) homogenates incubated in a water bath at different temperatures (4 degrees C, 25 degrees C or 37 degrees C, respectively) for two hours to induce autoxidation; 2) homogenates co-incubated with different concentrations of melatonin at 37 degrees C for 2 hours; 3) homogenates co-incubated with 1 mM vitamin C and different concentrations of hydrogen peroxide at 37 degrees C for 1 hour to induce membrane lipid peroxidation; 4) homogenates incubated with different concentrations of melatonin and 1 mM H2O2 plus 1 mM vitamin C. After incubation, homogenates were analyzed for products of lipid peroxidation (malondialdehyde and 4-hydroxy-alkenals). RESULTS: The levels of lipid peroxidation products significantly increased in monkey cerebral cortical homogenates as a consequence of autoxidation or after the addition of H2O2 plus vitamin C. Melatonin not only suppressed the increase in lipid peroxidation induced by H2O2 plus vitamin C but also inhibited lipid breakdown resulting from autoxidation. The concentrations of melatonin required to suppress lipid peroxidation resulting from autoxidation or induced by exogenous oxidants in monkey cerebral cortical homogenates were in the same dose range. CONCLUSION: The results show for the first time that melatonin functions as an antioxidant and neuroprotector in primate brain tissue as was observed previously in rodent brain. The data provide information supporting the use of melatonin in the treatment of neurodegenerative disorders that involve oxidative damage to brain lipids.