多梁式桥梁检测的叠加曲率模态差变化率方法

鉴于应用曲率模态的桥梁损伤识别研究大多以一维单梁式结构为研究对象,提出利用G-M法的思想并基于薄板振动理论将多梁式结构转化为正交异性板后,类比梁弯曲理论得到该结构两正交方向曲率表达式,通过分析采用单阶曲率模态差指标进行桥梁损伤识别的不足,考虑利用多阶曲率模态变化率叠加指标进行损伤识别,最后采用有限元软件Ansys建立桥梁模型计算单位置、多位置不同损伤程度的多种工况。Matlab绘图结果表明:沿桥梁纵向叠加指标识别更为精确,对未损伤位置数据扰动更小,指标独立性高,可利用该指标进行多梁式结构的损伤定位。     

具无界扰动的4阶非线性薛定谔方程的不变环面

考虑了狄利克雷边条件下的四阶非线性薛定谔方程iu_t+u_(xxxx)+|u_x|~2u_(xx)=0.利用一个无穷维KAM定理,证明上述方程存在大量的n-不变环面,从而得到方程存在大量的时间拟周期解.     

非稠定发展方程的全局吸引子

本文考虑一类发展方程在时滞存在和不存在两种情况下其全局吸引子的存在性,其中方程的线性部分不要求稠定.与前期工作[6,18]不同,此处去掉了线性算子生成的C0-半群的紧性假设,因此,本文中的方法适用范围更广.采用的主要技巧是广义的Gronwall不等式和Kuratowski非紧测度.作为对文中结论的应用,给出了线性算子生成的C0-半群非紧的例子.     

牛奶菜水提物对中华眼镜蛇毒神经毒性的抑制作用

【目的】考察牛奶菜(Marsdenia sinensis)水提物对中华眼镜蛇(Naja atra)毒神经毒性的抑制作用。【方法】利用四通道离体组织灌流系统和昆明小鼠(Mus musculus)离体回肠标本检测牛奶菜水提物对中华眼镜蛇毒神经毒性的抑制、即时中和与恢复作用。【结果】牛奶菜水提物对中华眼镜蛇毒神经毒性有一定抑制作用。【结论】研究结果揭示了牛奶菜用于治疗中华眼镜蛇咬伤的有效性,为后续开发抗蛇毒药物奠定了基础。     

基于地理加权相关的区域经济与民航运输空间关系分析

【目的】以第三产业增加值为经济增长需求指标,以旅客吞吐量、货邮吞吐量为民航运输生产供给指标,分析区域经济增长与民航运输生产的空间关系。【方法】使用地理加权相关分析计算地理加权相关系数,使用经验正交函数分析空间相关性变化的主要空间分布模式。【结果】第三产业与民航运输的空间相关性整体呈东部弱-西部强分布结构;近年来,第三产业与民航运输生产的空间相关性整体呈减弱变化趋势,中西部地区二者相关性逐年减弱是导致全国空间相关性减弱的主要驱动因素;通常情况下,省市经济规模越大,则它的第三产业与民航运输的相关性越弱。【结论】受经济产业活动聚集效应影响,东部发达省市经济增长对民航运输的依赖性普遍较弱,中西部省市对民航运输的依赖性较强;尽管近年来全国尺度上经济活动对民航运输的依赖性逐年减弱,但在经济增速放缓背景下,民航运输对中东部省市经济增长的拉动作用逐年增强。     

中华眼镜蛇血清对自身蛇毒中主要酶类活性的抑制作用

【目的】探究中华眼镜蛇(Naja atra)血清对自身蛇毒中主要酶类活性的抑制作用。【方法】不同稀释倍数的中华眼镜蛇血清与蛇毒于37℃孵育30min后,检测蛇毒中磷脂酶A2、透明质酸酶、乙酰胆碱酯酶、L-氨基酸氧化酶和5′-核苷酸酶活性的变化情况。【结果】中华眼镜蛇血清对自身蛇毒中磷脂酶A2和5′-核苷酸酶具有明显的抑制作用:当血清稀释2倍时,可以使蛇毒磷脂酶A2活性降低28.44%(p<0.001);当血清稀释8倍时,可以使蛇毒中5′-核苷酸酶活性活性降低23.44%(p<0.001)。中华眼镜蛇血清对自身蛇毒中的透明质酸酶、乙酰胆碱酯酶和L-氨基酸氧化酶均无抑制作用。【结论】中华眼镜蛇血清中存在蛇毒磷脂酶A2和5′-核苷酸酶的抑制剂,该结果为后期蛇毒抑制剂的筛选提供了理论依据。     

石柑子水提物对尖吻蝮蛇毒活性抑制作用的初步研究

【目的】寻找用于治疗尖吻蝮(Agkistrodon acutus)咬伤的中草药石柑子(Pothos chinensis)的药效实验证据。【方法】将制备所得石柑子水提物与尖吻蝮蛇毒混合孵育40min,检测混合液中蛇毒的磷脂酶 A2 活性、透明质酸酶活性、蛋白水解酶活性、出血活性、凝血活性和致死活性。【结果】石柑子水提物对尖吻蝮蛇毒的磷脂酶 A2 活性、透明质酸酶活性、蛋白水解酶活性、出血活性、凝血活性和致死活性都有明显抑制作用。【结论】研究结果初步证实了石柑子对尖吻蝮咬伤具有治疗效果。
     

Effect of high anodic polarization on the passive layer properties of superduplex stainless steel friction stir welds at different chloride electrolyte pH values and temperatures

The conditions used for friction stir welding of duplex stainless steels determine the resulting mechanical and corrosion performance of the material.This study investigates the corrosion resistance of UNS S32750 and S32760 superduplex stainless steels(SDSSs)joined by friction stir welding,employing cyclic polarization,Mott–Schottky,and microscopy techniques for analysis.The microscopy images indicated the presence of a deleterious intermetallic phase after electrolytic etching of S32760,as well as decreased corrosion resistance.The presence of molybdenum in the steels promoted better passive behavior at low pH.The Mott–Schottky curves revealed p-n heterojunction behavior of the passive oxide.Images acquired after the polarization test by scanning electron microscopy showed higher passivation propensity with increases of temperature and pH.     

Effects of small additions of Zn on the microstructure,mechanical properties and corrosion resistance of WE43B Mg alloys

Zn is a commonly used alloying element for Mg alloys owing to its beneficial effects on mechanical properties. To improve the mechanical and corrosion properties of WE43B Mg alloys, the effects of 0-0.7wt% Zn addition on the microstructure and properties of sample alloys were investigated. Addition of Zn to as-cast WE43B alloy promoted the formation of the Mg₁₂Nd phase; by contrast, after T6 heat treatment, the phase composition of WE43B alloys with and without Zn addition remained mostly the same. A long-period stacking ordered phase was predicted by CALPHAD calculation, but this phase was not observed in either the as-cast or heat-treated Zn-containing WE43B alloys. The optimum temperature and duration of T6 heat treatment were obtained using CALPHAD calculations and hardness measurements. Addition of Zn resulted in a slight reduction in the average grain size of the as-cast and T6 heat-treated WE43B alloys and endowed them with increased corrosion resistance with little effect on their mechanical properties.     

氧化铁/氧化锌超疏水复合材料的制备及其光催化性能

A facile approach was developed to construct Fe₂O₃-modified ZnO micro/nanostructures with excellent superhydrophobicity and photocatalytic activities. The effects of stearic acid (SA) and Fe₂O₃ on the morphological characteristics, water contact angle (WCA), and photocatalytic degradation were investigated. Superhydrophobicity results showed that WCA increased from 144° ± 2° to 154° ± 2° when the weight of SA increased from 5 to 20 mg because of the formation of a hierarchical or rough structure. Furthermore, Fe₂O₃-modified ZnO micro/nanostructure surfaces before and after SA treatment (20 mg) were chosen to evaluate the photodegradation of methylene blue (MB) dye under the support of visible light. MB degraded after 80 min of irradiation, and its photodegradation efficiencies were 91.5% at the superhydrophobic state and 92% at the hydrophilic state. This improvement in photocatalytic activity at both states might be attributed to an increase in surface area and improvement in charge carrier separation.