Method for evaluation of geological strength index of carbonate cliff rocks:Coupled hyperspectral-digital borehole image technique

The deterioration of unstable rock mass raised interest in evaluating rock mass quality.However,the traditional evaluation method for the geological strength index(GSI)primarily emphasizes the rock structure and characteristics of discontinuities.It ignores the influence of mineral composition and shows a deficiency in assessing the integrity coefficient.In this context,hyperspectral imaging and digital panoramic borehole camera technologies are applied to analyze the mineral content and integrity of rock mass.Based on the carbonate mineral content and fissure area ratio,the strength reduction factor and integrity coefficient are calculated to improve the GSI evaluation method.According to the results of mineral classification and fissure identification,the strength reduction factor and integrity coefficient increase with the depth of rock mass.The rock mass GSI calculated by the improved method is mainly concentrated between 40 and 60,which is close to the calculation results of the traditional method.The GSI error rates obtained by the two methods are mostly less than 10%,indicating the rationality of the hyperspectral-digital borehole image coupled evaluation method.Moreover,the sensitivity of the fissure area ratio(Sr)to GSI is greater than that of the strength reduction factor(a),which means the proposed GSI is suitable for rocks with significant fissure development.The improved method reduces the influence of subjective factors and provides a reliable index for the deterioration evaluation of rock mass.

Potential sliding zone recognition method for the slow-moving landslide based on the Hurst exponent

The abrupt occurrence of the Zhongbao landslide is totally unexpected,resulting in the destruction of local infrastructure and river blockage.To review the deformation history of the Zhongbao landslide and prevent the threat of secondary disasters,the small baseline subsets(SBAS)technology is applied to process 59 synthetic aperture radar(SAR)images captured from Sentinel-1A satellite.Firstly,the time series deformation of the Zhongbao landslide along the radar line of sight(LOS)direction is calculated by SBAS technology.Then,the projection transformation is conducted to determine the slope displacement.Furthermore,the Hurst exponent of the surface deformation along the two directions is calculated to quantify the hidden deformation development trend and identify the unstable deformation areas.Given the suddenness of the Zhongbao landslide failure,the multi-temporal interferometric synthetic aperture radar(InSAR)technology is the ideal tool to obtain the surface deformation history without any monitoring equipment.The obtained deformation process indicates that the Zhongbao landslide is generally stable with slow creep deformation before failure.Moreover,the Hurst exponent distribution on the landslide surface in different time stages reveals more deformation evolution information of the Zhongbao landslide,with partially unstable areas detected before the failure.Two potential unstable areas after the Zhongbao landslide disaster are revealed by the Hurst exponent distribution and verified by the GNSS monitoring results and deformation mechanism discussion.The method combining SBASInSAR and Hurst exponent proposed in this study could help prevent and control secondary landslide disasters.

Therapeutic effect of nerve growth factor on cerebral infarction in dogs using the hemisphere anomalous volume ratio of diffusion-weighted magnetic resonance imaging

A model of focal cerebral ischemic infarction was established in dogs through middle cerebral artery occlusion of the right side.Thirty minutes after occlusion,models were injected with nerve growth factor adjacent to the infarct locus.The therapeutic effect of nerve growth factor against cerebral infarction was assessed using the hemisphere anomalous volume ratio,a quantitative index of diffusion-weighted MRI.At 6 hours,24 hours,7 days and 3 months after modeling,the hemisphere anomalous volume ratio was significantly reduced after treatment with nerve growth factor. Hematoxylin-eosin staining,immunohistochemistry,electron microscopy and neurological function scores showed that infarct defects were slightly reduced and neurological function significantly improved after nerve growth factor treatment.This result was consistent with diffusion-weighted MRI measurements.Experimental findings indicate that nerve growth factor can protect against cerebral infarction,and that the hemisphere anomalous volume ratio of diffusion-weighted MRI can be used to evaluate the therapeutic effect.

Effects of nerve growth factor on the expression of caspase-12 of nerve cells in cerebral ischemia/reperfusion area

BACKGROUND： Researches suggest that cascade reaction of cysteine protease mediated by caspase-12 can cause apoptosis after cerebral ischemia/reperfusion injury; however, nerve growth factor （NGF） can reduce apoptosis through inhibiting activation of that reaction. OBJECTIVE： To observe the effect of NGF on the expression of caspase-12 in brain tissue of rabbits with cerebral ischemia/reperfusion injury, and elucidate the protective mechanism of NGF on neural apoptosis induced by cerebral ischemia/reperfusion injury. DESIGN： Randomized controlled animal study SETTING： Department of Image, Second Hospital, Hebei Medical University .MATERIALS ： A total of 26 healthy New Zealand rabbits, of clean grade, aged 4.5-5 months, weighing （2.6±0.2） kg, were selected in this study. Reagents： NGF （Xiamen Beida Zhilu Biotechnology Co., Ltd.）; caspase-12 （Santa Cruz Biotechnology Company, USA, clone number： SC-12395）; caspase-3 （Santa Cruz Biotechnology Company, USA, clone number： SC-7272）; biotin-antibody Ⅱ and ABC compound （Wuhan Boster Company）; in situ end-labeling （ISEL, Beijing Zhongshan Company）. METHODS： The experiment was carried out in the Laboratories of Nerve Molecule Image Science and Neurology of the Second Hospital of Hebei Medical University from May to August 2005. （1） All animals were randomly divided into three groups. Ischemia/reperfusion （I/R） group （n=10）： Left middle cerebral artery （MCA） was blocked for 2 hours and then blooded for 2 hours in order to establish focal cerebral ischemi- a/reperfusion models. Sham operation group （n=6）： Cork was inserted with 3 cm in depth, and then pulled to common carotid artery. Other procedures were as the same as those in ischemia/reperfusion group. Treatment group （n=-10）： After modeling, 400 AU （16 μg/L） NGF was inserted into cerebral infarction focus immediately. （2） Brain tissue was taken out from left ischemia/reperfusion area at 3 days after operation in sham operation group and at 3 days after reperfusion in other two groups, In addition, contents of caspase-12 and caspase-3 were measured with immunohistochemical technique; mean absorbency （A value） was compared with image analytic system; apoptosis rate and apoptosis quantity of nerves in ischemia/reperfusion area were detected with flow cytometry and DNA TdT-mediated biotinylated-dUTP nick end labeling method. （3） Measurement data were compared with one-way analysis of variance among groups and with q test every two groups. MAIN OUTCOME MEASURES： Expressions of caspase-12 and caspase-3 and apoptosis in cerebral ischemia/reperfusion area in the 3 groups. RESULTS： All 26 rabbits were involved in the final analysis. （1） Expressions of caspase-12 and caspase-3： Expression of caspase-12 was 0.36±0.02 in I/R group and 0.13±0.03 in treatment group; expression of caspase-3 was 0.49±0.05 and 0.27±0.06, respectively. Both of them were higher than those in sham operation group （0.07±0.02, 0.09±0.03, P 〈 0.01）, and expressions of two proteases were lower in treatment group than those in I/R group （P 〈 0.01）. There were significant differences of expression of caspase between I/R group and treatment group as compared with that in sham operation group; meanwhile, there were significant differences between treatment group and I/R group. （2） Apoptosis： Apoptosis rate was （20.2±1.3）% in I/R group and （7.7±0.8）% in treatment group; apoptosis quantity was （32.8±2.6）, （7.6±1.5） /high sight, respectively, Both of them were higher and more than those in sham operation group [（4.8 ±0.4）%, （0.7±0.2） /high sight, P 〈 0.01]. Apoptosis rate and apoptosis quantity were lower and less in treatment group than those in I/R group （P 〈 0.01）. There was significant difference between I/R group and treatment group as compared with sham operation group, and there was significant difference between treatment group and I/R group. CONCLUSION： NGF can decrease the number of apoptotic cells of the cerebral ischemia/reperfusion and inhibit the caspase cascade reaction induced by caspase-12, which is one of the protective mechanisms of NGF.

Reliability analysis of TBM disc cutters under different conditions

The reliability of disc cutters has a significant influence on the safety and working efficiency of tunnel boring machines(TBMs).To investigate the reliability of disc cutters under different geological and operational conditions,we conducted a series of novel rolling cutting tests on intact and jointed sandstone blocks using different dip angles and interlayers.Different normal forces and rotational speeds of the cutterhead were also applied during the experiment.A novel reliability estimation method,based on a logistic regression model,was then proposed,and the influence of dip angle,strata,normal force,and rotational speed on the reliability of the disc cutter were analyzed.The reliability estimation method consisted of data acquisition regarding the normal force and cutter wear,feature extraction using wavelet packet transform and correlation analysis,and the estimation of the logistic regression model.To obtain the spectrum and normalized wavelet energy for each frequency band,we decomposed the time domain of the normal force by the wavelet packet transform.A correlation analysis was employed to determine the feature frequency bands that were sensitive to wear loss.On the basis of salient feature parameters and wear loss,the logistic regression model was established to evaluate the reliability of disc cutters.The analytical results indicated that the optimal dip angle for rock cutting was 30°.In the presence of mixed-face and single ground,the reliability of disc cutters was primarily affected by the difficulty of TBM excavation and wear loss,respectively.An increase in normal force and rotational speed aggravated wear on the cutter,thus reducing reliability.Furthermore,compared with Rabinowicz’s formula,the proposed method considers various geological and operational conditions,making the proposed method more applicable to estimate the reliability of disc cutters.