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1.
Titanium dioxide (TiO_2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO_2 thin film by 3-aminopropyltrietboxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO_2 thin film. We found that, with UV irradiation, the silani-zation level of the irradiated area of the TiO_2 film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO_2 can act as a coating material on the biosensor surface to improve the effect and effi-ciency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO_2 film. The hybridization of probe DNA and target DNA was monitored by the recording of Ⅰ-Ⅴ curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 μmol/L of target DNA sample.  相似文献   

2.
Neurochip based on light-addressable potentiometric sensor(LAPS),whose sensing elements are excitable cells,can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed.Here we report a kind of neurochip with rat pheochromocytoma(PC12) cells hybrid with LAPS and a method of de-noising signals based on wavelet transform.Cells were cultured on LAPS for several days to form networks,and we then used LAPS system to detect the extracellular potentials with signals d...  相似文献   

3.
The aim was to investigate how the PI3K/Akt pathway is involved in the protection of dexmedetomidine against propofol. The hippocampal neurons from fetal rats were separated and cultured in a neurobasal medium. Cell viability was assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Then neurons were pretreated with different concentrations of dexmedetomidine before 100 μmol/L propofol was added. Akt, phospho-Akt (p-Akt), Bad, phospho-Bad (p-Bad), and Bcl-xL were detected by Western blot. Also, neurons were pretreated with dexmedetomidine alone or given the inhibitor LY294002 before dexmedetomidine pretreatment, and then propofol was added for 3 h. The results demonstrated that propofol decreased the cell viability and the expression of p-Akt and p-Bad proteins, increased the level of Bad, and reduced the ratio of Bcl-xL/Bad. Dexmedetomidine pretreatment could reverse these effects. The enhancement of p-Akt and p-Bad induced by dexmedetomidine was prevented by LY294002. These results showed that dexmedetomidine potently protected the developing neuron and this protection may be partly mediated by the PI3K/Akt pathway.  相似文献   

4.
将Cu2＋和碳纳米管（MWNTs）固定于脱氧核糖核酸（DNA）和聚丙烯胺（PAA）中形成MWNTs／Cu2＋-DNA／PAA纳米复合物,并用此纳米复合物构建了一种新的过氧化氢生物传感器。结果表明,在pH=5．0的磷酸盐缓冲溶液中,所制备的生物传感器对过氧化氢的线性范围为5．0μmol／L--4mmol／L,检测下限为2．5μmol／L（S／N=3）。这种新型传感器的优越性在于它可以克服天然酶易失活、不稳定的缺点而具有良好的重现性与稳定性。  相似文献   

5.
E‐learning tools and technologies have been used to supplement conventional courses in higher education institutions creating a “hybrid” e‐learning module that aims to enhance the learning experiences of students. Few studies have addressed the acceptance of hybrid e‐learning by learners and the factors affecting the learners’ satisfaction with these tools. This study assesses hybrid e‐learning acceptance by learners using three critical success factors: instructor characteristics, information technology infrastructure, and organizational and technical support. Structural equation modeling was applied to examine and validate the hypothesized relationships among the three factors and their effects on learners’ acceptance of hybrid e‐learning. A total of 538 usable responses from university students were used to validate the proposed research model. The influence of the three factors on learners’ decision to accept hybrid e‐learning was empirically examined. The results show that all three factors significantly and directly impacted the learners’ acceptance of hybrid e‐learning courses. Information technology infrastructure and organizational support were proven to be key determinants of the instructor characteristics as a critical success factor of hybrid e‐learning acceptance by learners. Implications of this work for higher education institutions, researchers, and instructors are described.  相似文献   

6.
By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance (QCM) biosensor for Escherichia coli O157H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid (MHDA) was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide (NHS) raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor's resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×102 colony forming units (CFU)/ml E. coli O157H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed.  相似文献   

7.
混合动力客车的控制策略决定整车的性能。分析某混联式混合动力客车的组成结构和基于逻辑控制的控制策略,建立相应的混联式混合动力客车仿真模型及其控制器,通过AVL/CRUISE和MATLAB/Simulink联合仿真分析,获得该车在中国典型城市公交工况下的动力性和百公里油耗。仿真结果表明,各主要部件能按照控制规则实现状态的合理切换,基于逻辑控制的控制策略能满足整车性能指标要求。  相似文献   

8.
A simple and controllable layer-by-layer (LBL) assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes (MWNTs) and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly(allylamine hydrochloride) (PAH) and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue (MB) could mix well with horseradish peroxidase (HRP) to form a biocompatible and negativelycharged HRP-MB biocomposite. A (PAH-MWNTs/HRP-MB) n bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response (2 s) to hydrogen peroxide with a low detection limit of 2.0×10−7 mol/L (S/N=3). This work provided a versatile platform in the further development of reagentless biosensors.  相似文献   

9.
A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine (HESM) is introduced in this paper. The generator is connected to an uncontrollable rectifier, and a fully controlled voltage-source inverter is used to connect the system to utility grid. An intermediate DC bus exists between the rectifier and inverter. A new control strategy is proposed which achieves the maximum power point tracking (MPPT) with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously. Specially-designed buck circuit is used to control the excitation current of HESM, and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power. Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.  相似文献   

10.
This study aimed to analyze the volatile chemical profile of Longjing tea, and further develop a prediction model for aroma quality of Longjing tea based on potent odorants. A total of 21 Longjing samples were analyzed by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Pearson’s linear correlation analysis and partial least square (PLS) regression were applied to investigate the relationship between sensory aroma scores and the volatile compounds. Results showed that 60 volatile compounds could be commonly detected in this famous green tea. Terpenes and esters were two major groups characterized, representing 33.89% and 15.53% of the total peak area respectively. Ten compounds were determined to contribute significantly to the perceived aroma quality of Longjing tea, especially linalool (0.701), nonanal (0.738), (Z)-3-hexenyl hexanoate (−0.785), and β-ionone (−0.763). On the basis of these 10 compounds, a model (correlation coefficient of 89.4% and cross-validated correlation coefficient of 80.4%) was constructed to predict the aroma quality of Longjing tea. Summarily, this study has provided a novel option for quality prediction of green tea based on HS-SPME/GC-MS technique.  相似文献   

11.
This paper presents a new method based on an immune-tabu hybrid algorithm to solve the thermal unit commitment （TUC） problem in power plant optimization. The mathematical model of the TUC problem is established by analyzing the generating units in modem power plants. A novel immune-tabu hybrid algorithm is proposed to solve this complex problem. In the algorithm, the objective function of the TUC problem is considered as an antigen and the solutions are considered as antibodies, which are determined by the affinity computation. The code length of an antibody is shortened by encoding the continuous operating time, and the optimum searching speed is improved. Each feasible individual in the immune algorithm （IA） is used as the initial solution of the tabu search （TS） algorithm after certain generations of IA iteration. As examples, the proposed method has been applied to several thermal unit systems for a period of 24 h. The computation results demonstrate the good global optimum searching performance of the proposed immune-tabu hybrid algorithm. The presented algorithm can also be used to solve other optimization problems in fields such as the chemical industry and the power industry.  相似文献   

12.
设计了膜生物反应器 (MBR)与粉末活性炭 (PAC)联合使用的膜组合工艺 (PAC MBR)处理微污染地表水 ,并用分子量分析方法来考察PAC MBR组合工艺及各单元工艺对有机物的去除效果 .分析结果表明 ,由于原水中的小分子有机物难生物降解 ,该工艺出水有机物集中在小于 1k的分子量区间内 ,活性炭的投加能显著提高这部分有机物的去除率 .试验证明 ,PAC MBR工艺中生物处理与活性炭吸附互相促进 ,在稳定运行阶段对CODMn、UV2 54 、UV4 10 和氨氮的去除率分别达到 70 %、70 %、10 0 %和 92 % .  相似文献   

13.
Educational materials often present general concepts or strategies via specific people. Although this practice may enhance interest, it may also have costs for learning and transfer. Linking a strategy to a person (e.g., “Molly’s strategy”) could result in narrower transfer because students infer that the strategy is specific to the person, rather than a general strategy they should adopt. The present study tested this hypothesis among middle school students (N = 191) who learned a novel strategy for solving a mathematics story problem. For some students, the strategy example was presented via a specific person, and for others it was not. Students then solved posttest problems and rated the generality of the strategy. Students who saw the example without the person were more likely to transfer the strategy to new problems, and this effect was mediated by students’ perceptions of the strategy’s generality. Thus, associating information with a person substantially limits the extent to which students transfer their knowledge.  相似文献   

14.
类脂双层研究的动力来自动物世界,1961年首次报道了生物体的双层类脂膜(BLM)自组装.BLM体系已广泛应用于对生物能、光合成、免疫学和生物传感器等多种物理学现象的研究.文章在综述了类脂双层的起源及形成机理的基础上,从理论上分析了类脂双层的电学参量,以及类脂双层应用于生物传感器的应用前景.  相似文献   

15.
通过对高粱 苏丹草杂交种品质性状的调查与分析 ,发现高粱 苏丹草杂交种营养丰富 ,氰化物含量低 ,适口性好 ,可作为畜牧、水产养殖业青刈或青贮的优质饲料  相似文献   

16.
Formative assessment, bilingualism, and argumentation when combined can enrich bilingual scientific literacy. However, argumentation receives little attention in the practice of bilingual science education. This article describes the effect of a formative assessment-based pedagogical strategy in promoting university students’ argumentation. It examines the written and oral arguments produced by 54 undergraduates (28 females and 26 males, 16–21 years old) in Colombia during a university bilingual (Spanish-English) science course. The data used in this analysis was derived from students’ written responses, and audio and video recordings. The first goal of this study was to determine how this teaching strategy could help students increase the use of English as a means of communication in argumentation in science. The second goal was to establish the potential of the strategy to engage students in argumentative classroom interactions as an essential part of formative assessment. The findings show that the strategy provided participants with opportunities to write their argumentation in Spanish, in English and in a hybrid version using code-switching. Educational implications for higher education are discussed.  相似文献   

17.
The calcium phosphate (CaP) particles have attracted much attention in gene therapy. How to construct stable gene particles was the determining factor. In this study,hybrid multi-shell CaP gene particles were successfully constructed. First,CaP nanoparticles served as a core and were coated with DNA for colloidal stabilization. The ξ-potential of DNA-coated CaP nanoparticles was -15 mV. Then polyethylenimine (PEI) was added and adsorbed outside of the DNA layer due to the electrostatic attraction. The ξ-pot...  相似文献   

18.
INTRODUCTION In some large scale corporations and virtual or-ganization environment (education system, military organizations, etc.), much electronics information resources are distributed physically and diverse in types. Each unit of an organization manages some resources respectively, according to the domain knowledge or the particular mission. In technical aspect, each unit is a node working independently in the information network. These nodes can join or leave the network at any tim…  相似文献   

19.
A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network (WDM/OCDMA-PON) based on superstructure fiber Bragg grating (SSFBG) and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBG, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re-modulation technology is also a good method to save wavelength-specific components at the optical network unit (ONU) and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels (with the same OC) are found to be negligible in upstream and downstream transmissions.  相似文献   

20.
以聚丙烯酸丁酯（PBA）乳液为主体材料,硅溶胶为前驱体,用溶胶一凝胶法制备PBA／SiO2杂化材料,在此基础上加入硫化剂制备了PBA／SiO2杂化材料硫化胶,研究了硫化剂用量对杂化材料硫化胶力学性能的影响,通过平衡溶胀实验测定了硫化胶的表观交联密度,用差示扫描量热仪（DSC）和热重分析（TG）对杂化材料硫化胶的结构进行了表征。平衡溶胀实验结果表明,六甲醇醚化三聚氰胺甲醛树脂（HMMM）的加入使杂化材料硫化胶的交联密度增加。结果证明,HMMM对于PBA／SiO2杂化材料是有效交联剂。  相似文献   

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