A DNA vaccine induces SARS coronavirus neutralization and protective immunity in mice

Public health measures have successfully identified and contained outbreaks of the severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV), but concerns remain over the possibility of future recurrences. Finding a vaccine for this virus therefore remains a high priority. Here, we show that a DNA vaccine encoding the spike (S) glycoprotein of the SARS-CoV induces T cell and neutralizing antibody responses, as well as protective immunity, in a mouse model. Alternative forms of S were analysed by DNA immunization. These expression vectors induced robust immune responses mediated by CD4 and CD8 cells, as well as significant antibody titres, measured by enzyme-linked immunosorbent assay. Moreover, antibody responses in mice vaccinated with an expression vector encoding a form of S that includes its transmembrane domain elicited neutralizing antibodies. Viral replication was reduced by more than six orders of magnitude in the lungs of mice vaccinated with these S plasmid DNA expression vectors, and protection was mediated by a humoral but not a T-cell-dependent immune mechanism. Gene-based vaccination for the SARS-CoV elicits effective immune responses that generate protective immunity in an animal model.     

Inhibition of xanthine oxidase by liquiritigenin and isoliquiritigenin isolated from Sinofranchetia chinensis

The methanol extract of the stem of Sinofranchetia inhibited the activity of xanthine oxidase in vitro. Bioassay-guided purification led to the isolation ofliquiritigenin and isoliquiritigenin as the main xanthine oxidase inhibitors. This inhibition of enzyme activity was found to be dose dependent, with an IC50 value of approximately 49.3 microM for liquiritigenin and 55.8 microM for isoliquiritigenin. Lineweaver-Burk transformation of the inhibition data indicated that the inhibition was of a mixed type for both liquiritigenin and isoliquiritigenin. For liquiritigenin, the Ki and K(I) were determined to be 14.0 microM and 151.6 microM, respectively. For isoliquiritigenin, the Ki and K(I) were determined to be 17.4 microM and 81.9 microM, respectively. These results suggest that these natural products could be used to treat conditions where the inhibition of xanthine oxidase is warranted.     

四君子汤对荷瘤小鼠红细胞免疫功能的影响

采用郭峰等人的方法,进行了四君子汤对荷瘤小鼠红细胞免疫功能影响的体内实验研究.结果表明:四君子汤能明显提高荷瘤小鼠的RBC-C3bRR和RFER,降低RBC-ICRR和RFIR.这一结果表明四君子汤对荷瘤小鼠红细胞免疫有显著的促进作用.     

对微孔AlPO_4-5分子筛水热合成中部分影响因素的研究

微孔磷酸铝分子筛AlPO4-5是一种具有代表性的磷酸盐分子筛,其优良的催化性能已得到广泛的肯定.其凝胶的组成直接影响到产品的组成和性质.以三乙胺为模板剂,拟薄水铝石、分析纯磷酸为原料,180℃下晶化36 h水热合成AlPO4-5分子筛.并以X-射线粉末衍射(XRD)对其进行结构鉴定、电子显微技术对其进行形貌表征.分别考察了水量改变、模板剂量改变及水量和模板剂量同时改变对AlPO4-5分子筛合成的影响.     

基于平稳脊波变换的图像降噪

有限脊波变换在Radon变换域中用正交小波处理点奇异,而正交小波变换不存在冗余性,因此在应用有限脊波变换进行图像降噪时会产生Gibbs现象。为了解决Gibbs条纹干扰问题,本文在有限脊波变换的基础上提出一种新的基于平稳脊波变换的图像降噪方法,其关键是引入一维平稳小波变换来代替正交小波变换对Radon系数矩阵进行处理。实验结果表明,与基于有限脊波变换的图像降噪方法相比,本文提出的算法具有更优的降噪性能,可使图像降噪后保持更好的边缘特征和视觉效果,振铃效应得到改善。     

济南城市绿地空间格局对鸟类群落结构的影响研究

依据城市绿地空间格局的成因,借助遥感技术、GIS 技术和景观格局分析方法,从人为属性、非生物属性、生物属性方面量化城市绿地空间格局因子,分析了济南市14个城市绿地中的鸟类群落结构与城市绿地空间格局因子之间的关系,探讨了城市绿地空间格局对鸟类群落结构的影响。研究发现,城市绿地空间格局中的分维度、建筑面积百分比、绿地面积百分比、植被多样性、草本多样性、人流量、音量是影响鸟类群落的关键因子。     

LLR calculation for LDPC coded SCBT in 60 GHz WPAN

The single-carrier block transmission (SCBT), a.k.a., single-carrier frequency-domain equalization (SC-FDE), is being considered as an option technique for the wireless personal area network (WPAN) operating at 60 GHz. It is found that for residential environment, in non-line-of-sight (NLOS) multi-path channels, the SCBT is much more effective to combat the inter-symbol interference (ISI) compared with orthogonal frequency division multiplexing (OFDM). Low-density parity-check (LDPC) codes are a class of linear block codes which provide near capacity performance on a large collection of data transmission and storage channels while simultaneously admitting implementable decoders. To facilitate using LDPC codes for SCBT system, a new log-likelihood ratio (LLR) calculation method is proposed based on pilot symbols (PS). Golay Sequences whose sum autocorrelation has a unique peak and zero sidelobe are used for creating the PS. The position and length of the PS are not fixed in the data blocks. The simulation results show that the proposed method can significantly improve the LDPC decoding performance in SCBT system. This is very promising to support ultra high-data-rate wireless transmission.     

基于VSG的储能逆变器控制策略及无缝切换技术

为应对储能逆变器在并离网切换时产生的电压波动和冲击电流,基于微网孤岛和并网运行模式的特点,提出虚拟同步发电机控制策略。通过对微网无缝切换关键技术分析,提出基于频率扰动的微网预同步控制。为实现控制策略的无缝切换,利用VSG控制和PQ控制共用电流内环,实现外环参考电流平滑过渡,确保控制策略切换时刻和PCC开关动作时刻的同步性,保证了VSG在两种运行模式之间平滑切换,有利于微网的稳定运行。在MATLAB/Simulink仿真平台下搭建模型,验证所提控制策略和切换方法的有效性和可行性。     

考虑残余顶推力作用时盾构下穿引起既有顶管管廊变形

针对隧道开挖引起上覆既有顶管管廊变形的工况,提出了一种可考虑顶管管廊残余顶推力的管廊竖向变形理论计算方法。第一阶段采用修正Loganathan公式解得隧道开挖引起周围土体的自由位移,把土体自由位移附加在既有管廊轴线上,第二阶段将既有管廊简化成无限长Euler-Bernoulli梁搁置在Pasternak地基模型上,同时考虑管廊轴力对其变形响应的影响,随后根据管廊两端自由的约束条件提出了隧道开挖引起既有管廊受力变形半解析解。研究结果表明：与某工程实测数据验证对比,本文方法计算结果与实测较为符合;与本文方法退化解析比较,本文方法预测结果更具有优越性。进一步参数得到如下结论：地层损失率的增大会使得既有管廊位移及其内力呈现线性增大的趋势;随着管廊直径的增大,既有管廊位移和弯矩会迅速增大,其增速也在不断增大;随着隧道开挖轴线埋深的增加,既有管廊位移和内力均会大幅度减小。