Advanced Materials Research Vols. 236-238

Abstract: The important factors induced corrosion damage of aircraft are analyzed. Based on airport ground environment spectrum, the LY12CZ specimens are tested in laboratory using the accelerated corrosion spectrum. Some specimens are exposed on deck in tropical marine environment. The corrosion characteristic of the coating and base material is inspected and corrosion damage size is measured after the specimens have been accelerated corrosion tested for 5,10,15,20 and 30 years respectively and the specimens have been exposed on deck. The corrosion characteristic of specimens are analyzed and compared using several evaluating indicator. The results show that the corrosion damage characteristic of the specimen in the test is consistent with which in service situations. And the corrosion of material exposed in ocean environment is obviously accelerated. The corrosion depth is measured and the mass loss by corrosion is weighed. The distribution function of the corrosion depth and the characteristic of the mass loss by corrosion are given. The corrosion equivalent relationship under these two environments is determined by contrasting the corrosion depth and the corrosion characteristic.

Abstract: The paper established the model of the practical Model test rig rotor-bearing system using finite element method, and discusses the phenomena of oil whirl and oil whip occurred in fluid lubricated bearing. The characteristics of stability of the nonlinear rotor-bearing system were numerically studied under different unbalance and different parameter of bearings, the model simulations are compared with measurements at the test rig, which can provide the theoretical reference for forecasting malfunction of oil film instability.

Abstract: Acanthopanax Senticosus is a traditional medicinal plant in China. Flavonoids are one of the main active ingredients of this plant. Four extraction technologies of flavonoids from Acanthopanax Senticosus were investigated and compared, including microwave-assisted extraction, ultrasonic extraction, reflux extraction and Soxhlet extraction. The results showed that microwave-assisted extraction was most suitable for the extraction of flavonoids from Acanthopanax Senticosus because of its high effect and short extraction time. The found optimum extraction conditions were that the ethanol concentration was 50% (v/v), solid–liquid ratio was 1:50, extraction temperature was 50°C and irradiation time was 9 min. Quantification was performed by means of UV–Vis spectrophotometry with chromogenic system of NaNO₂–Al (NO₃)₃–NaOH. Under the optimum conditions, the calibration curve for the analyte was linear with the correlation coefficients greater than 0.9999. The average recovery was 101.8%, and its RSD was 0.87%(n=5). The total content of flavonoids was18.72 mg g⁻¹.

Abstract: Flavonoids from Sweet potato vines are often regarded as a functional ingredient to promote nutritional value of food. In this study, the antioxidant activity of flavonoids from Sweet potato vines was evaluated by various methods with ascorbic acid as control standards. The results showed that flavonoids could inhibit lipid peroxidation, increase reducing power, scavenge hydroxyl free radicals, superoxide anions and DPPH radicals. Those antioxidant properties of the flavonoids depended on flavonoids content and increased with increasing of sample content. The flavonoids were better than ascorbic acids on inhibiting lipid peroxidation, but it was weaker than ascorbic acids on reducing power and scavenging hydroxyl free radicals, superoxide anions and DPPH radicals. ID₅₀ (50% inhibiting dose) of inhibiting lipid peroxidation, scavenging hydroxyl free radicals, superoxide anions and DPPH radicals of the flavonoids was 17.48μg, 204.95μg, 139.02μg, 138.35μg separately. Therefore, the flavonoids from sweet potato vines is a kind of natural and effective antioxidant and free radical remover.

Abstract: Two 1-allyl-3-butylimidazolium ionic liquids were synthesized and polymerized in- column as stationary phases in capillary gas chromatography. The influences of different counter ions (hexafluorophosphate, tetrafluoroborate) were studied. The results indicated that 1-allyl-3-butyl- imidazolium ionic liquids possessed good column coating properties and chromatographic separation abilities after polymerized in-column. The Grobs mixture, alcohols and alkanes and aromatic position isomers, such as xylene, nitrotoluene, dichlorobenzene and cresol were separated well. These polymeric ionic liquids gave potential to separate some complex compounds including alcohol, amine, ester etc.

Abstract: In this study, the volatile compounds of pepper (Piper Nigrum L.) were extracted and analyzed by simultaneous distillation-extraction (SDE) and gas chromatography-mass spectrometry (GC-MS). The differences in volatile compounds were observed by GC-MS data sets. Results showed vinyl compounds were the most dominant volatiles in pepper by simultaneous distillation-extraction (SDE) and GC-MS, and 22 volatile compounds in the white pepper and black pepper were the same.

Abstract: The effects of frozen storage time on the functional properties of frozen wheat gluten were evaluated. The frozen wheat gluten was subjected to frozen storage in refrigerator at－18°C for 0–120days. The samples were obtained by the process of freeze-drying. The main functional properties of frozen wheat gluten were determined to confirm the effects of frozen storage time on functional properties of frozen wheat gluten. Results showed that solubility, water-holding capacity, emulsifying capacity, foamability and foam stability of frozen wheat gluten decreased and that oil-holding capacity, emulsion stability of frozen wheat gluten were improved with prolonged frozen storage time.

Abstract: The single factor experiment method was used to investigate the effects of microwave power（P）, extraction pressure(p), alcohol mass concentration（x%）, ratio of liquid to solid (l/s), pre-immersed time(τ) and particle size(d) on extraction efficiency of total isoflavones from pueraria lobata by pressurized microwave-assisted extraction technique. Based on the above the Design-Expert 6.0 software was used to carry out a response surface test with three factors (ratio of liquid to solid, pressure and alcohol mass concentration) to optimize the technical conditions and establish the mathematical model. The results show that the optimum technical conditions are: P =700w, p =132.61kPa, x =51.2%, l / s =10.45,τ=2h，d = 80 meshes. Under these conditions the extraction efficiency reaches 98.75% which is 23.5% higher than that by microwave-assisted extraction at atmospheric pressure. The established model (second multivariate regression equation) is consistent with the experiment and can predict the extraction efficiency of the total isoflavones under different technical conditions.

Abstract: The aim of the present study was to investigate the effects of improving ripening temperature on Gouda cheese. In order to evaluate the quality changes of Gouda cheese with different temperature (12°C,15°C,18°C) during its ripening period, the change of soluble nitrogen (SN）, protein hydrolysis, texture properties were measured. Ripening temperature had a significant effects on SN concentration and protein degradation. Results showed that the Gouda cheese with best quality was ripened at 15°C after 90d.

Abstract: An accident instantaneous release of LPG can results in a rapidly expanding two-phase flammable cloud, which is the medium of potentially disastrous consequences. In this paper, CFD (Computational Fluid Dynamics) method was applied for instantaneous LPG release in an open environment in order to analysis the expansion process of two-phase cloud. The results from simulation are compared with the published experimental data to validate the model. Statistical analysis of experimental data is used to set the initial conditions and computational inlet in the model. The mass and heat transfer is calculated in eulerian-lagrangian method. The features in expansion process are studied by the analyses of the variation of size, temperature, volume averaged rate of evaporation of the cloud and entropy of the whole flow field.