MWCNTs-rGO/PDDA-AuNPs复合膜修饰电极对莱克多巴胺的灵敏检测

采用自组装方法,将聚二烯丙基二甲基氯化铵(PDDA)功能化的金纳米颗粒(Au NPs)负载于多壁碳纳米管(MWCNTs)-还原型氧化石墨烯(r GO)夹层,再涂覆于玻碳电极(GCE)上,制备了纳米复合膜修饰电极MWCNTs-r GO/PDDA-Au NPs/GCE.采用透射电子显微镜(TEM)和紫外-可见光谱(UV-Vis)对修饰膜的形貌及结构进行表征.探讨了其对莱克多巴胺(Rac)的循环伏安行为,结果表明MWCNTs-r GO/PDDA-Au NPs纳米复合物对Rac表现出显著的电催化氧化特性.采用差分脉冲伏安法测得该复合膜修饰电极对Rac检测的线性范围为0.036~4.5μmol/L,检出限为6.35 nmol/L(S/N≥3),且显示出良好的抗干扰能力、稳定性及重现性.采用该方法检测猪血清及猪尿样中的Rac,回收率达95.4%~105.9%,表明该复合膜修饰电极对实际样品中Rac的检测具有潜在应用价值.     

Proposal for underwater structural analysis using the techniques of ESPI and digital holography

The purpose of this article is to study the application of the holographic interferometry techniques in the structural analysis of submarine environment. These techniques are widely used today, with applications in many areas. Nevertheless, its application in submarine environments presents some challenges. The application of two techniques, electronic speckle pattern interferometry (ESPI) and digital holography, comparison of advantages and disadvantages of each of them is presented. A brief study is done on the influence of water properties and the optical effects due to suspended particles as well as possible solutions to minimize these problems.     

The last departure time from an M t /G/∞ queue with a terminating arrival process

This paper studies the last departure time from a queue with a terminating arrival process. This problem is motivated by a model of two-stage inspection in which finitely many items come to a first stage for screening. Items failing first-stage inspection go to a second stage to be examined further. Assuming that arrivals at the second stage can be regarded as an independent thinning of the departures from the first stage, the arrival process at the second stage is approximately a terminating Poisson process. If the failure probabilities are not constant, then this Poisson process will be nonhomogeneous. The last departure time from an M _t /G/∞ queue with a terminating arrival process serves as a remarkably tractable approximation, which is appropriate when there are ample inspection resources at the second stage. For this model, the last departure time is a Poisson random maximum, so that it is possible to give exact expressions and develop useful approximations based on extreme-value theory.      

A network queuing approach for evaluation of performance measures in autonomous vehicle storage and retrieval systems

A network queuing approach is used to estimate performance measures for Autonomous Vehicle Storage and Retrieval (AVS/R) Systems using opportunistic interleaving. The model exploits the distribution of cycle types and random storage assumptions to estimate the proportion of single and dual command cycles in a system. Comparable in accuracy and computational efficiency to procedures based on standard queuing models, the proposed technique provides the additional advantage of flexibility for modeling the interfaces between a storage system and the overall material flow system in a facility. The procedure is demonstrated for a range of problem scenarios.     

The robustness of the semi-Markov and delay time single-component inspection models to the Markov assumption

The context of planned preventive maintenance lends itself readilyto probabilistic modelling. Indeed, many of the published theoreticalmodels to be found in the literature adopt a Markov approach,where states are usually ‘operating’, ‘operatingat one of several levels of deterioration’, and ‘failed’.However, most of these models assume the required Markovianproperty and do not address the issue of testing the assumption,or the related task of estimating parameters. It is possiblethat data are inadequate to test the assumption, or that theMarkov property is believed to be not strictly valid, but acceptableas an approximation. In this paper we consider within a specificinspection–maintenance context the robustness of a Markov-basedmodel when the Markov assumption is not valid. This is achievedby comparing the output of an exact delay time model of an inspection–maintenanceproblem with that of a semi-Markov approximation. The importanceof establishing the vadility of the Markov property in the modellingapplication is highlighted. If the plant behaviour is seen tobe nearly Markov, in the case considered the semi-Markov modelgives a good approximation to the exact model. Conversley ifthe Markov assumption is not a good approximation, the semi-Markovmodel can lead to inappropriate advice.     

Inspection of a magneto-optical trap via electromagnetically induced absorption

Electromagnetically induced absorption (EIA) was observed for the first time on a sample of ⁸⁵Rb in a magneto-optical trap using low intensity cw copropagating pump and probe optical fields. Narrow resonances revealing the dependence of the ground-state Zeeman sublevels energy structure on the quadrupolar magnetic field and the trapping optical field intensity at different trap positions, were observed. Coherence resonances as narrow as 30 kHz were obtained under low trapping field intensities. The use of EIA spectroscopy for the magnetic field mapping of cold atomic samples is illustrated.     

Nitrite and N-Nitrosocompounds Trace Assay Using a Simple Solid-Phase Technique

Abstract

A new solid-phase technique “Maniscale” is described. The sensor is designed as microcolumn divided into working and neutral segments alternating with each other. Working zones are filled with granulated agaropectin in H-form partially substituted with rivanol. In the presence of nitrite and excess of chloride ions rivanol is self-diazocoupled to red diazodye. Pre-packed analytical set gives possibility to simple and sensitive assay in hygienic and environmental inspection.     

拉曼光谱在液体安检中的应用及发展趋势

在民航、轨道交通、重要场馆安保等领域的液体安检中,现在主要的技术有三种:介电常数测量技术、拉曼光谱分析技术以及基于X射线的检测技术,但每种技术都不能单独地满足实际需求。拉曼光谱技术可以在液体安检以及违禁品检测中发挥重要作用。未来拉曼光谱技术将在以下方面得到发展:1、采用新技术提升仪器性能;2、增加谱图库扩大技术的应用范围;3、与表面增强拉曼光谱技术结合实现违禁品的探测。     

基于一类优化BP神经网络模型的中国廉租房条件(家庭贫困)界定研究

建立家庭情况界定评价指标体系,通过采样居民家庭经济状况,建立优化BP神经网络用于计算贫困指数、贫困级差数实现家庭贫困界定,运用软件鉴定结果,并将原理推广到其他评价方法.     

外星推进剂质量检测标准分析

对比分析了国内外卫星推进剂在取样方法、质量检测方法、检测指标等方面所依据标准的差异,分析了我国推进剂检测实验室依据国际标准对外星推进剂进行质量分析的能力,为推进剂检测实验室具备和提高外星推进剂质量分析的能力提出了具体的措施。