有机立体化学分子构型教学中的几点做法

用 R,S构型命名法描述手性分子的绝对构型教学是大学化学教学的一个难点和重点。探讨了应用直接观察法、计算法、手模型法来确定分子的 R,S构型命名。

Choice of approach for hepatectomy for hepatocellular carcinoma located in the caudate lobe:Isolated or combined lobectomy?

AIM:To investigate the significance of the surgical approaches in the prognosis of hepatocellular carcinoma(HCC) located in the caudate lobe with a multivariate regression analysis using a Cox proportional hazard model.METHODS:Thirty-six patients with HCC underwent caudate lobectomy at a single tertiary referral center between January 1995 and June 2010.In this series,left-sided,right-sided and bilateral approaches were used.The outcomes of patients who underwent isolated caudate lobectomy or caudate lobectomy combined with an additional partial hepatectomy were compared.The survival curves of the isolated and combined resection groups were generated by the Kaplan-Meier method and compared by a log-rank test.RESULTS:Sixteen(44.4%) of 36 patients underwent isolated total or partial caudate lobectomy whereas 20(55.6%) received a total or partial caudate lobectomy combined with an additional partial hepatectomy.The median diameter of the tumor was 6.7 cm(range,2.1-15.8 cm).Patients who underwent an isolated caudate lobectomy had significantly longer operative time(240 min vs 170 min),longer length of hospital stay(18 d vs 13 d) and more blood loss(780 mL vs 270 mL) than patients who underwent a combined caudate lobectomy(P < 0.05).There were no perioperative deaths in both groups of patients.The complication rate was higher in the patients who underwent an isolated caudate lobectomy than in those who underwent combined caudate lobectomy(31.3% vs 10.0%,P < 0.05).The 1-,3-and 5-year disease-free survival rates for the isolated caudate lobectomy and the combined caudate lobectomy groups were 54.5%,6.5% and 0% and 85.8%,37.6% and 0%,respectively(P < 0.05).The corresponding overall survival rates were 73.8%,18.5% and 0% and 93.1%,43.6% and 6.7%(P < 0.05).CONCLUSION:The caudate lobectomy combined with an additional partial hepatectomy is preferred because this approach is technically less demanding and offers an adequate surgical margin.

Smartphone Malware Detection Model Based on Artificial Immune System

In order to solve the problem that me traditional signature-based detection technology cannot effectively detect unknown malware, we propose in this study a smartphone malware detection model （SP-MDM） based on artificial immune system, in which static malware analysis and dynamic malware analysis techniques are combined, and antigens are generated by encoding the characteristics extracted from the malware. Based on negative selection algorithm, the mature detectors are generated. By introducing clonal selection algorithm, the detectors with higher affinity are selected to undergo a proliferation and somatic hyper-mutation process, so that more excellent detector offspring can be generated. Experimental result shows that the detection model has a higher detection rate for unknown smartphone malware, and better detection performance can be achieved by increasing the clone generation.

Malware Detection in Smartphones Using Static Detection and Evaluation Model Based on Analytic Hierarchy Process

Mobile malware is rapidly increasing and its detection has become a critical issue. In this study, we summarize the common characteristics of this inalicious software on Android platform. We design a detection engine consisting of six parts： decompile, grammar parsing, control flow and data flow analysis, safety analysis, and comprehensive evaluation. In the comprehensive evaluation, we obtain a weight vector of 29 evaluation indexes using the analytic hierarchy process. During this process, the detection engine exports a list of suspicious API. On the basis of this list, the evaluation part of the engine performs a compre- hensive evaluation of the hazard assessment of software sample. Finally, hazard classification is given for the software. The false positive rate of our approach for detecting rnalware samples is 4. 7% and normal samples is 7.6%. The experimental results show that the accuracy rate of our approach is almost similar to the method based on virus signatures. Compared with the method based on virus signatures, our approach performs well in detecting unknown malware. This approach is promising for the application of malware detection.

Finite Order Batalin-Fradkin-Tyutin Method for Chiral Bosons in Non-commutative Space

The recently improved finite order BFT Hamiltonian embedding method is applied to the two dimensional chiral bosons in non-commutative space. It is then systematically converted to a first class constraint model. Performing the momentum integrations, the corresponding fully gauge symmetry Lagrangian as well as its partition function in phase space are obtained.

High-finesse displacement sensor and a theoretical accelerometer model based on a fiber Fabry-Perot interferometer

A displacement sensor based on the fiber Fabry-Perot (F-P) cavity was proposed in this paper. Theoretical and experimental analyses were presented. Displacement resolution was demonstrated by spectrum-domain experiments to obtain the dynamic range of the F-P sensor, and a piezoelectric crystal unit (PZT) was used as the driver. The output signal was modulated by a piezoelectric ceramic ring and demodulated by a phase-locked oscillator. The experimental results show that the displacement resolution of the F-P sensor is less than 5 nm and the dynamic range is more than 100 μm. As acceleration is the second-order differential of displacement, an accelerometer model was proposed using the finite element method (FEM) nd ANSYS software.