Because of strong current, friction and arcing, electrical contact ablation occurs in the transmitting process of electromagnetic railgun, which is also one key issue in application. In this paper, an experimental apparatus is designed to detect electromagnetic railgun armature contacts ablation. Energy dispersive X-ray, scanning electron microscopy, high-resolution camera and rogowski coil are used to measure mass loss, volume change, the ablation layer analysis, the element distribution on ablation layer section and the electrical contact analysis. Experimental results show that the input current and the contact pressure between electrodes are the major factors contributing to the ablation volume loss and mass loss. It is also showed that as a sliding electrode, the aluminum armature ablates more seriously during launch.

With 298 heterogeneous soil samples from Yixing (Jiangsu Province), Zhongxiang and Honghu (Hubei Province), this study aimed to combine a successive projections algorithm (SPA) with a support vector machine regression (SVMR) model (SPA-SVMR model) to improve the estimation accuracy of soil organic carbon (SOC) contents using the laboratory-based visible and near-infrared (VIS/NIR, 350-2500 nm) spectroscopy of soils. The effects of eight spectra pre-processing methods, i.e., Log (1/R), Log (1/R) coupled with Savitzky-Golay (SG) smoothing (Log (1/R) + SG), first derivative with SG smoothing (FD), second derivative with SG smoothing (SD), SG, standard normal variate (SNV), mean center (MC) and multiplicative scatter correction (MSC), on SPA-based informative wavelength selection were explored. The SVMR model (i.e., SVMR without SPA) and SPA-PLSR model (i.e., SPA combined with partial least squares regression (PLSR)) were developed and compared with the SPA-SVMR model in order to evaluate the performance of SPA-SVMR. The results indicated that the variables selected by SPA and their distributions were strongly affected by different pre-processing methods, and SG was the optimal pre-processing method for SPA-SVMR model development; the SPA-SVMR model using SG pre-processing and 28 SPA-selected wavelengths obtained a better result (R-V(2) = 0.73, RMSEV = 2.78 g center dot kg(-1) and RPDV = 1.89) and outperformed the SVMR model (R-V(2) = 0.72, RMSEV = 2.83 g center dot kg(-1) and RPDV = 1.86) and the SPA-PLSR model (R-V(2) = 0.62, RMSEV = 3.23 g center dot kg(-1) and RPDV = 1.63). Most of the spectral bands used by the SPA-SVMR model over the near-infrared region were important wavelengths for SOC content estimation. This study demonstrated that the combination of SPA and SVMR is feasible and reliable for estimating SOC content from the VIS/NIR spectra of soils in regions with multiple soil and land-use types.

Hydroxyethyl chitosan (HECTS) is a critical derivative of chitosan that has been widely used as biomedical materials due to great water-solubility and excellent biocompatibility. Here, photosensitive hydroxyethyl chitosan was synthesized by introducing azide group on NH2 of HECTS (HECTS-AZ), afterwards FTIR and H-1 NMR spectra were detected to confirm the formation of HECTS-AZ. The solution of HECTS-AZ can achieve a sol-gel transition through UV irradiation for 30 s. The evaluation of biocompability and biodegradability in vivo was conducted in rats, visual and pathological examinations exhibited the HECTS-AZ has excellent biocompability and degradation time of the hydrogel is more than 14 weeks. Furthermore, HECTS-AZ hydrogel as an ocular drug delivery system loading heparin was prepared to implant under sclera of rabbit after glaucoma filtration surgery (GFS). The experimental results demonstrated the heparin loaded hydrogel can effectively maintain filtration bleb and lowing intraocular pressure (IOP) after GFS for prolonged time. Besides, obvious inflammatory reactions and side effects have not been observed in ocular during the experimental period. In conclusion, the HECTS-AZ hydrogel is a potential drug delivery device for the treatment of glaucoma and other ocular diseases.

The inactivation of peroxidase (POD) and polyphenol oxidase (PPO) in red beet extract with high pressure carbon dioxide (HPCD) was investigated. HPCD treatment at 37.5 MPa for POD and 22.5 MPa. for PPO (55 degrees C, 60 min) resulted in a reduction of their activities by approximately 86% and 95%, respectively. Compared with thermal treatment (55 degrees C), the decimal reduction time (D) of POD and PPO was reduced from 555.56 min to 74.63 min and 161.29 min to 38.31 min, respectively, by the HPCD treatment. The inactivation process followed first-order kinetics (R(2) > 0.84, p<0.05) with D values declining with the rise of pressure and temperature. The activation energy of the inactivation was reduced by the HPCD treatment from 92.54 kJ/mol to 68.63 kJ/mol and 57.06 kJ/mol to 53.58 kJ/mol for POD and PPO, respectively. Analysis of the kinetic parameters of the inactivation showed that both POD and PPO were less sensitive to pressure changes under supercritical than subcritical conditions. (C) 2007 Elsevier Ltd. All rights reserved.