电学开路挠曲电悬臂梁自振频率分析

挠曲电效应是一种新兴的机电耦合效应,在微纳米尺度的传感器、致动器和俘能器方面有广阔的应用前景.本文基于挠曲电材料的变分原理和电吉布斯自由能,推导了表面覆盖电极的挠曲电悬臂梁在电学开路条件下的机电耦合动力学控制方程和相应的力电边界条件.进一步获得了求解电学开路条件下挠曲电悬臂梁自振频率的超越方程.以聚偏氟乙烯(PVDF)材料为算例,讨论了挠曲电系数、末端质量块和梁尺寸对结构自振频率和电学开路/短路条件下结构自振频率有效频移的影响.计算结果表明,挠曲电系数的增大会提高梁的自振频率;末端质量的增大可以降低梁的自振频率,并且末端质量块的转动效应对悬臂梁自振频率的影响很小;悬臂梁结构的有效频移随着结构尺寸减小而增加,并在某一厚度尺寸趋于饱和值.国家自然科学基金(11572271

Determination of Chondroitin Sulfate with High Sensitivity by Fluorescence Recovery through Shifting the Equilibrium between Anionic Phthalocyanine and Cationic Surfactant

目的建立高灵敏荧光增强法测定硫酸软骨素的新方法,并用于实际样品测定。方法对荧光光谱行为的考察显示,在PH 7.0的介质中,具有共轭结构的阳离子头部和长碳链尾部的阳离子表面活性剂对四磺基铝酞菁(AlS4PC)的荧光具有高效猝灭作用,二者形成无荧光离子缔合物。此离子缔合物可对带有磺酸基团的高分子黏多糖硫酸软骨素(CS)作出灵敏响应。在CS的存在下,反应体系荧光显著恢复,最大恢复倍数可达900倍。由于猝灭效率高,荧光恢复程度大,甚至可实现目视化观测。结果工作曲线响应区间0.2~6μg·Ml-1,检测限0.09μg·Ml-1,工作曲线lOgy=0.158 23ρ-0.035 97,r=0.998 7。本实验对该法用于批量样品分析的可行性进行了考察,结果表明,所建立的方法可望用于高通量分析。结论该法操作简便,灵敏度、稳定性与检测准确性好。所建立的方法成功地用于组成复杂的实际样品中CS的定量分析,解决了实际工作中的难点。OBJECTIVE To propose a novel method for quantitative determination of chondroitin sulfate in real samples using the ion-association phthalocyanine complex as a fluorescent probe emitting at red-region.METHODS The fluorescence of tetrasulpnonated aluminum phthalocyanine( AlS4Pc),an anionic metal phthalocyanine,was quenched dramatically by cationic surfactants which contain a positively-charged head with a conjugated structure and a long carbon chain as tail through the formation of an almost non-fluorescent association complex.Hexadecylpyridinium bromide( CPB) screened from a series of cationic surfactants was selected as a quencher because of its high fluorescence quenching efficiency.It was found that the ion-association complex( AlS4Pc-CPB) emitted strong fluorescence in the presence of chondroitin sulfate,due to the ability of chondroitin sulfate to shift the association equilibrium of the ionassociation complex,which led to the release of AlS4Pc,thus resulting in an increase in the fluorescence of AlS4Pc.The method based on the above-mentioned phenomenon was investigated in the aspects of spectral characteristics,effect of pH,influence of reaction time, order of addition of reagents,the usage of reagents,and interference of foreign substances.RESULTS Under optimal conditions,the linear range of the assay for chondroitin sulfate was 0.2- 6 μg·mL- 1with a detection limit of 0.09 μg·mL- 1.CONCLUSOIN The established method is not only sensitive,accurate but also simple and reliable.It has been used to the analysis of real samples with complicated composition with satisfactory results.It has also been successfully applied in batch test combined with well-reader technique,exhibiting great potential for high-throughput analysis.福建省科技重点资助项目(2012Y0081); 福建省公益类科研院所基本专项(2010R1101)资助项

The Effect of Flexoelectricity on Performance of Simple Support Beam Piezoelectric Sensors

挠曲电效应是材料极化强度(或电场强度)与应变梯度之间的耦合关系,对于新型微纳米致动器和传感器的性能具有重要的影响.以纳米简支梁式压电传感器(简称; 压电简支梁)为研究对象,讨论材料的挠曲电效应对压电简支梁输出电势与挠度的影响.采用电吉布斯自由能密度函数,并根据压电材料线性理论与伯努利-欧拉梁; 理论,采用变分法推导压电简支梁的控制方程和相应力电耦合边界条件.数值模拟${\rm{BaTi}}{{\rm{O}}_{\rm{3}}}$压电简支; 梁在外加机械载荷作用下,由于挠曲电效应产生的诱导电势和极化强度等与梁结构、材料参数的相互关系.计算结果表明,诱导电势反馈作用在梁的表面引起一个与; 机械载荷作用相反的弯矩,减小了梁结构的弯曲挠度;在一定的挠曲电系数和梁结构尺寸下,诱导电势存在最大值;在微纳尺度上挠曲电效应具有很强的尺寸依赖性; ,随着梁的厚度增大,挠曲电效应的影响将显著减弱.The flexoelectric effect is the coupling between the polarization (or; electric field) and the strain gradient,which has important influence on; the new micro-nano actuator and sensor.In this paper,the simply; supported piezoelectric nanobeams have been used to study the effect of; flexoelectricity on the induced electric potential and deflection of; sensors.Based on the electric Gibbs free energy density function,the; linear piezoelectric theory and the Bernoulli-Euler beam theory,the; governing equations and the boundary conditions are deduced by the; variation method.Using numerical simulations,the relationships between; the induced electric potential/ polarization and the material; parameters/structure sizes of ${\rm{BaTi}}{{\rm{O}}_{\rm{3}}}$ simple; support sensors have been obtained under the mechanical loading.These; results show that the induced electric potential due to the; flexoelectricity causes a reversed moment,which opposes those; mechanically induced and decreases the deflection of the beams.The; maximum induced electric potential exists with the appropriate; flexoelectric coefficient and beam thickness.The results also show that; the flexoelectric effect has a strong size-dependent on; micro-nanoscale.With the thickness of the; ${\rm{BaTi}}{{\rm{O}}_{\rm{3}}}$ piezoelectric nanobeam increasing,the; effect of flexoelectricity decreases significantly.国家自然科学基

Novel Method for Determination of Lysozyme Based on Fluorescence Recovery of a Cationic Aluminum Phthalocyanine-Mucopolysaccharides Association Complex Used as a Red Emitting Fluorogenic Substrate

在弱酸性介质中,具有红区发射特性的强荧光化合物阳离子铝酞菁(TTMAAlPC)在带磺酸基团的低浓度阴离子黏多糖(肝素,HP)的存在下,发生诱导聚集,导致酞菁荧光几乎完全猝灭。此聚集缔合物可作为溶菌酶的荧光底物,在溶菌酶的水解作用下,HP降解为小分子片段,破坏了TTMAAlPC的诱导聚集行为而使其释放,体系荧光显著恢复。据此现象,建立了测定溶菌酶的新方法。结合荧光光谱与荧光各向异性技术对反应机理进行了探讨。确定了最佳反应条件(醋酸缓冲体系,PH4.0、反应温度70$C、反应时间30 MIn),考察了共存物质的影响。在最佳条件下,方法的线性回归方程为y=#30.12121+214.65772X,r=0.99871,线性范围为0.2~2 Mg/l,检出限0.015 Mg/l。本研究操作简便且有较好的选择性和灵敏度。本方法用于溶菌酶实际样品的测定,并与常规的比浊法进行了比较,结果符合良好。本研究将阳离子金属酞菁荧光探针用于酶分析,开拓了酞菁荧光探针的应用范围。We developed a novel method for the rapid determination of lysozyme using a new fluorogenic substrate that consists of a cationic aluminum phthalocyanine( tetra( trimethylammonio) aluminum phthalocyanine,TTMAAlPc), and an anionic mucopolysaccharide( heparin, HP).We found that fluorescence from the cationic aluminum phthalocyanine,a red-region fluorescence probe,was quenched significantly in acidic media in the presence of low concentrations of anionic mucopolysaccharide heparin( HP) bearing anionic sulfonic acid groups,because of induced aggregation.The practically non-fluorescent substrate degraded into small molecular fragments upon the hydrolysis of lysozyme, and thus the phthalocyanine molecules aggregated in HP were released,resulting in significant fluorescence recovery in the reaction system.This phenomenon forms the foundation of the proposed method.The reaction mechanism was determined using fluorescence spectroscopy and fluorescence anisotropy techniques.Factors that affected the determination were investigated.Under optimal conditions,the linear range was 0.2- 2 mg /L,and the detection limit was 0.015 mg /L.The developed method is easy to operate and has good selectivity and sensitivity.This method was used in the analysis of practical samples of lysozyme,and the results were in agreement with those determined by a conventional turbidimetric method.国家自然科学基金重大研究计划项目(No.90206016); 福建省科技重点项目(No.2012Y0081); 福建省属公益类科研院所基本科研专项(No.2010R1039-3)~

Sensitive Determination of Chondroitin Sulfate by Fluorescence Recovery of an Anionic Aluminum Phthalocyanine-Cationic Surfactant Ion-Association Complex Used as a Fluorescent Probe Emitting at Red Region

硫酸软骨素的测定在生物医学领域有重要价值,但常规检测法在灵敏度、选择性或简易性方面尚存在不足。本文基于带正电基团的阳离子表面活性剂对具有红区发射特性的强荧光化合物—荷负电的四磺基铝酞菁具有高效荧光猝灭作用,而在生物多糖硫酸软骨素存在下,上述荧光猝灭体系荧光显著恢复的现象,提出酞菁-表面活性剂离子缔合物荧光恢复高灵敏测定硫酸软骨素的新方法,并用于实际样品分析。研究表明,中性介质中,红区荧光探针四磺基铝酞菁(TETrASulfOnATEd AluMInIuM PHTHAlOCyAnInE,AlS4PC)与阳离子表面活性剂十四烷基二甲基苄基氯化铵(TETrAdECyldIMETHylbEnzylAMMOnIuM CHlOrIdE,TdbAC)发生强烈的缔合作用,导致AlS4PC的荧光几乎完全猝灭,从而获得暗背景的荧光体系。在加入带有阴离子基团(磺酸基)的生物多糖硫酸软骨素(CHOndrOITIn SulfATE,CS)后,由于竞争结合作用,AlS4PC被释放而使体系的荧光大幅度恢复,且恢复程度与CS呈线性正相关。优化了反应条件,考察了共存物质的影响,结果表明本法具有较好的选择性。在最佳条件下,线性范围为0.20~10.0μg·Ml-1,检测限为0.070μg·Ml-1,工作曲线方程y=1.04X+2.09,r=0.999 5。该法操作简便,灵敏度、稳定性与准确性好,实际样品的分析结果令人满意。酞菁荧光化合物在分析科学中的应用尚不多见,本文工作进一步开拓了酞菁红区荧光探针的新应用。Determination of chondroitin sulfate in the biomedical field has an important value.The conventional methods for the assay of chondroitin sulfate are still unsatisfactory in sensitivity,selectivity or simplicity.This work aimed at developing a novel method for sensitive and selective determination of chondroitin sulfate by fluorimetry.We found that some kinds of cationic surfactants have the ability to quench the fluorescence of tetrasulfonated aluminum phthalocyanine(AlS4Pc),a strongly fluorescent compound which emits at red region,with high efficiency.But,the fluorescence of the above-mentioned fluorescence quenching system recovered significantly when chondroitin sulfate(CS)exits.Tetradecyl dimethyl benzyl ammonium chloride(TDBAC)which was screened from all of the candidates of cationic surfactants was chosen as the quencher because it shows the most efficient quenching effect.It was found that the fluorescence of AlS4 Pc was extremely quenched by TDBAC because of the formation of association complex between AlS4 Pc and TDBAC.Fluorescence of the association complex recovered dramatically after the addition of chondroitin sulfate(CS)due to the ability of chondroitin sulfate to shift the association equilibrium of the association,leading to the release of AlS4 Pc,thus resulting in an increase in the fluorescence of the reaction system.Based on this phenomenon,a novel method with simplicity,accuracy and sensitivity was developed for quantitative determination of CS.Factors including the reaction time,influencing factors and the effect of coexisting substances were investigated and discussed.Under optimum conditions the linear range of the calibration curve was 0.20~10.0μg·mL-1.The detection limit for CS was 0.070μg·mL-1.The method has been applied to the analysis of practical samples with satisfied results.This work expands the applications of AlS4 Pc in biomedical area.福建省科技重点项目(2012Y0081); 福建省公益类科研院所基本专项项目(2010R1101;2014R1102); 厦门市科技项目(3502Z20143015)资

Securely redundant scheduling policy for MapReduce based on dynamic domains partition

MapReduce现有调度策略无法实现云环境中多租户作业的安全隔离。提出一种基于动态域划分的安全冗余调度策略：通过引入冲突关系、信任度、安全标签等概念，建立一种动态域划分模型，以将待调度节点划分为与不同租户作业关联的冲突域、可信域或调度域；结合冗余方式，将租户作业同时调度到其可信域节点和调度域节点(但不允许为其冲突域节点)，通过二者执行环境和部分计算结果的一致性验证决定是否重新调度。实验分析了其有效性和安全性。 MapReduce’s current scheduling policies could not ensure the isolation between multi-tenant Tasks in the cloud. A securely redundant scheduling policy based on dynamic domains partition was proposed. First, a kind of dy-namic domain partition model was introduced in this policy. Based on the node’s current belief, security labels with the conflict relationship between tenants, a computing node was partitioned into the conflict domain, trusted domain or schedulable domain in this model. Second, through redundantly computing, two copies of each Task were assigned re-spectively to its trusted domain node and its schedulable domain node (but not allow for its conflict domain node) in this policy. And the integrity of the two nodes’execution environments and the consistence of their results on a small part of original input data were verified. Accordingly, it decided whether the schedulable domain node was trusted. Finally, the performance and security analysis in the prototype show its effectiveness.MapReduce's current scheduling policies could not ensure the isolation between multi-tenant Tasks in the cloud. A securely redundant scheduling policy based on dynamic domains partition was proposed. First, a kind of dynamic domain partition model was introduced in this policy. Based on the node's current belief, security labels with the conflict relationship between tenants, a computing node was partitioned into the conflict domain, trusted domain or schedulable domain in this model. Second, through redundantly computing, two copies of each Task were assigned respectively to its trusted domain node and its schedulable domain node (but not allow for its conflict domain node) in this policy. And the integrity of the two nodes' execution environments and the consistence of their results on a small part of original input data were verified. Accordingly, it decided whether the schedulable domain node was trusted. Finally, the performance and security analysis in the prototype show its effectiveness

CSR注入引出高压静电偏转板设计

　利用3维电磁场计算程序MAFIA对CSR注入引出静电偏转板的物理结构进行了理论设计。该偏转板高压电极材料采用表面经过阳极氧化处理的锻铝板材,倒角半径为20mm,电极半宽度60mm,其几何形状能够同时满足电场均匀性、耐压性及机械强度的要求,切割板电极采用半钨丝半钽板的结构,入口厚度不大于0.1mm。在设计基础上制造了偏转板模型,并对之进行了真空模拟试验,结果证明该高压静电偏转板的设计方案是合理的,基本满足物理实验要求

长期禁食对尿酸代谢的影响及其调控机制探讨

为研究长期禁食过程中大鼠尿酸代谢的变化及其潜在的调控机制，以Sprague-Dawley（SD）大鼠为动物模型，通过病理组织切片、生化检测、荧光定量PCR（qRT-PCR）以及蛋白免疫印迹（Western blotting）等方法分析不同禁食时间（1，2，3，5，7天）大鼠尿酸水平及其代谢相关基因和蛋白的表达变化。结果表明，长期禁食未对大鼠肾脏组织产生明显的损伤，引起了血尿酸水平上升、尿尿酸水平波动性变化和血液尿酸酶活性升高；随着禁食时间的延长，主要尿酸转运蛋白的mRNA和蛋白表达水平逐渐上调。长期禁食过程中大鼠尿酸代谢变化可能与尿酸转运蛋白及尿酸酶活性有关

Fe-N Doped Hollow Carbon Nanospheres Linked by Carbon Nanotubes for Oxygen Reduction Reaction

以ZIF-8为模板，通过表面包覆聚多巴胺、同时刻蚀ZIF-8中的Zn2+，形成空心球，在与三氯化铁络合后，经高温碳化和氨气热处理，得到了高比表面积的Fe-N共掺杂的碳纳米管串联的碳纳米空心球催化剂. 氨气不仅刻蚀碳基底提高比表面积，还可还原铁元素形成Fe4N纳米粒子，提升了催化剂对氧还原反应的电催化活性，其氧还原半波电位达0.79 V，仅比商业Pt/C低60 mV，而且其稳定性和耐甲醇性更优于商业Pt/C，展示出良好的燃料电池应用潜力.The development of non-precious metal catalysts for oxygen reduction reaction (ORR) is essential for large-scale application of proton exchange membrane fuel cells. Herein, we present the in situ formed Fe-N doped hollow carbon nanospheres linked by carbon nanotubes composite, synthesized by using ZIF-8 as sacrificed template to form polydopamine (PDA) hollow nanospheres, followed by complexing with FeCl3, high temperature heat-treatment and NH3-etching. ZIF-8 was gradually decomposed simultaneously with PDA coating due to the loss of Zn2+ grabbed by PDA. NH3 etching resulted in the improved surface area, while the reducibility of NH3 resulted in the formation of Fe4N nanoparticles, which benefits the ORR activity of the catalyst. The half-wave potential of the as-prepared of PDA-Fe/N/C-NH3 was 0.79 V, only 60 mV lower than that of commercial Pt/C. The stability and methanol tolerance of PDA-Fe/N/C-NH3 were even superior to that of commercial Pt/C, indicating the good potential of PDA-Fe/N/C-NH3 for the application of fuel cells.黑龙江省自然科学基金（No. QC2013C008）资助作者联系地址：1. 中国科学院上海高等研究院， 上海 201210； 2. 中国科学院大学， 北京 100049Author's Address: 1. Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China；2. University of Chinese Academy of Sciences, Beijing 100049, China通讯作者E-mail：[email protected]; [email protected]