Applied Mechanics and Materials Vols. 195-196

Abstract: Ethanol extracts from Hohenbuehelia serotina and Armillaria mellea fruit bodies were prepared and investigated for their antioxidant capacities in three different assays, namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, reducing power and chelating ability on ferrous ions. Among the two mushrooms, ethanol extracts from A. mellea was more effective than that from H. serotina in scavenging DPPH free radical ability, while ethanol extracts from H. serotina was some higher than that from A. mellea in reducing power. With regard to chelating effect on ferrous ions, at 5 mg/mL, chelating ability of ethanol extracts from H. serotina were 43.17 %, while that from A. mellea was 46.54%. It can be concluded that ethanol extracts from A. mellea and H. serotina were good in antioxidant properties.

Abstract: This paper used the germination rate of Phoebe zhennan seeds in field to present the vigor, the content of MDA, the integrality of cell membrane system, the rate of superoxide anion generation and the content of H₂O₂ were evaluated. The results showed that the content of MDA, the relative electrolyte leakage, the rate of superoxide anion generation and the content of H₂O₂ of Phoebe zhennan seeds increased with the aged time increase, which indicated that the increase of the lipid peroxidation, lose of the integrality of cell membrane system, the rate of superoxide anion generation and the content of H₂O₂ induced the vigor dropping and the quality becoming poor for Phoebe zhennan seeds.

Abstract: Microwave-Induced Thermo-Acoustic Tomography (MITAT) own much concerns in recent years in biomedical imaging field. High contrast and resolution compared with conventional microwave or ultrasound imaging system especially for malignant tumors are outstanding characters of it. In this paper, the induced thermo-acoustic wave propagating in a mimic biologic tissue is simulated by numeric method Pseudo-Spectrum Time Domain (PSTD). Due to the excellent performance in noise-depress and the stability for the fluctuation of the model parameters, Time Reversal Mirror (TRM) imaging technique is studied computationally for the simulative received thermo-acoustic signals. Some thermo-acoustic objects with different initial pressure distribution are designed and imaged by TRM technique to represent the complex biologic tissue case in a random media. The quality of images generated by TRM technique based on PSTD method hints the potential of the MITAT technique.

Abstract: The extraction of flavonoids from clovers was optimized to maximize flavonoid yield Y in this study. A central composite design of response surface methodology involving extracting time, liquid-solid ratio, extracting temperature and ethanol concentration was used, and second-order model for Y was employed to generate the response surfaces. The optimum condition for Y was determined as follows: extracting time 24min, liquid-solid ratio 20, extracting temperature 80°C, and ethanol concentration 72%. Under the optimum condition, the flavonoid yield was 2.49%.

Abstract: In this paper, numerical simulation of sound field with short focal length is performed, which is based on spheroidal beam equation (SBE) in frequency-domain for transducer with a wide aperture angle. And we made some experiments on vitro bovine liver to explore the characteristic of sound pressure and-3dB sound focal region at different positions of incident interface. It is found that with a fixed curvature radius if the focal length is shorter under the skin, the amplitude of sound pressure will be higher on the focus and the shape of-3dB sound focal region will be smaller. When the incident interface is in the range of planar wave, nonlinear effect is strong and the focus will change with the interface position. Especially when the position is near to transition location between planar wave and spheroidal wave, the nonlinear effect is lowered. While the focus is closer to the sound source so as to burn the scarfskin easily. When the interface is in the range of spheroidal wave, the focus position changes little but the side lobe effect due to refraction is obvious. And the focusing performance of transducer will be affected. The experimental results validate the accuracy of theoretical results. It is concluded that the position of incident interface should be selected reasonably with short focal length in the treatment of superficial tissue.

Abstract: nterferon-alpha (IFN-a) is a kind of cytokines that share antiviral, as well as immunomodulatory, and antiproliferative effects on cell functions. In this report, the cDNA for Ailuropoda melanoleucas interferon alpha was cloned from the ConA-stimulated giant panda peripheral blood mononuclear cells (PBMCs) by RT-PCR. Bioinformatics analysis was performed to predict the characteristics of this gene. Sequencing revealed that the fragment was composed of 495 nucleotides, intronless, encoding a mature polypeptide with 164 amino acids and exhibiting a molecular mass of 18.15 kDa. The analysis of the functional sites and antigenic determinants demonstrated that this protein has 27 functional sites and 9 antigenic determinants, And possesses typical characteristics of interferon alpha, beta and delta family. Compared with 10 corresponding IFN-α sequences. It revealed that the GpIFN-a gene had a close evolutionary relationship with mammalians IFN-a. Phylogenetic tree based on nucleotide sequences showed that giant panda, ferret, dog and cat clustered together and evolved into a distinct phylogenetic lineage. In conclusion, all the data and consequences will provide a basis for further functional study of the Ailuropoda melanoleuca IFN-a.

Abstract: Comparative molecular similarity indices analysis (CoMSIA) were performed on N-dichloroacetyl oxazolidine derivatives as herbicide safeners. The best CoMSIA models that were generated using atom based alignmen, R_cv²=0.632, n=4, R²=0.927, F=31.796 and s=0.097. The contributions of steric field, electrostatics field, hydrophobicities field and hydrogenbond acceptor were 0.127, 0.260, 0.285 and 0.328, respectively. The CoMSIA model was satisfactory and would be useful for the future design of new N-dichloroacetyl oxazolidine herbicide safener.

Abstract: In this paper, a novel kernel taking into consideration of the physico-chemical properties of amino acids as well as the motif information is proposed to tackle the problem of protein classification. Similarity matrix is constructed based on an AAindex2 substitution matrix which measures the amino acid pair distance. Together with the motif content posing importance on the protein sequences, a new kernel is constructed. Numerical examples indicate that the string-based kernel in conjunction with SVM classifier performs significantly better than the traditional spectrum kernel method.

Abstract: Protein 3D structure is one of the main factors in reecting gene functions. The availability of protein structure data in Protein Data Bank (PDB) allows us to conduct gene function analysis based on protein structure data. However, the molecules in PDB, whose structures having been determined, are always not corresponding to a unique gene. That is to say, the mapping from a gene to the PDB is not one-to-one. This feature complicates the situation and increases the difculty of gene function analysis. In this paper, we attempt to tackle this problem and also study the problem of predicting gene function from protein structures based on the gene-PDB mapping. We rst obtain the gene-PDB mapping, which is used to represent a gene by the structure set of all its corresponding PDB molecules. We then dene a new gene-gene similarity measurement based on the structure similarity between PDB molecules, and we further show that this new measurement matches with the gene functional similarity. This means that the measurement we dened here can be used effectively for gene function prediction.

Abstract: Purposes: To construct a recombinant vaccine alpha-fetoprotein (AFP)-glycoprotein (gp96) complex, and study its ability to induce specific CTL response and its protective effect against AFP-producing tumor. Material/Methods: A recombinant vaccine was constructed by conjugating mouse alpha-fetoprotein to glycoprotein 96. By way of intracutaneous injection, mice were primed and boosted with recombinant vaccine mAFP/gp96, whereas single mAFP or gp96 injection as controls. The ELISPOT and ELISA were used to measure the frequency of cells producing the cytokine IFN-gama in splenocytes and the level of anti-AFP antibody of serum from immunized mice respectively. In vivo tumor challenge was carried out to assess the immune effect of the recombinant vaccine. Results: By recombinant mAFP/gp96 vaccine immunization, the results of ELISPOT and ELISA showed that the number of splenic cells producing IFN-gama and the level of anti-AFP antibody of serum were significantly higher in mAFP/gp96 group than those in mAFP and gp96 groups (122.50±9.30 IFN-gama spots/10⁶ cells vs 46.40±10.32 IFN-gama spots/10⁶ cells, 12.14±7.33 IFN-gama spots/10⁶ cells, P<0.01; 164.52±11.22 µg/mL vs 56.32±8.23 µg/mL, 7.56±3.47 µg/mL, P< 0.01). The tumor volume in mAFP/gp96 group was significantly smaller than that in mAFP and gp96 groups (32.46±6.35 mm³ vs 384.16±11.43 mm³, 832.54±12.72 mm³, P< 0.01). Conclusions: The study further confirmed the function of glycoprotein 96s immune adjuvant. Sequential immunization with recombinant mAFP/gp96 vaccine could generate effective antitumor immunity on AFP-producing tumor. The recombined mAFP/gp96 vaccine may be suitable for serving as an immunotherapy for hepatocellular carcinoma.