Research Watch: On-line nitrification monitoring sensor

Measurements.     

Effect-based and chemical analysis of polycyclic aromatic hydrocarbons in smoked meat: a practical food-monitoring approach

Polycyclic aromatic hydrocarbons (PAHs), which are generated by heat treatment and smoke curing of meat, pose a risk to human health. At present, the determination of these unwanted contaminants requires costly, time-consuming chemical analysis of smoked meat. An alternative is effect-directed high-throughput bioassays, which could also be used as a pre-screening method. The authors recently adapted the in vitro chemical-activated luciferase gene expression (CALUX) assay as a rapid, sensitive, and inexpensive screening technique for compounds such as dioxins, polychlorinated biphenyls, and PAHs. The aim of the present study was to apply a practical approach under realistic conditions. Custom-made meat samples produced under defined conditions with different PAH levels were analysed using this bioassay and gas chromatography-mass spectrometry (GC/MS) to determine the influence of different smoking conditions (temperature and duration) on PAH levels. It was found that cold smoking for up to 6 h did not result in strong PAH contamination, whereas hot (65°C) and longer smoking times caused a considerable increase in both the bioassay response and the levels of 31 individually determined PAHs. The response in the effect-based bioassay was in good agreement with the values of chemical analysis. The bioassay made it possible to determine accurately the degree of contamination. The results show that this assay is suitable for high-throughput screening for unknown levels of toxicologically relevant PAHs in meat samples and is sensitive enough to differentiate between different PAH levels generated under various smoking conditions. Effect-based screening techniques, therefore, provide a new instrument for official food monitoring.     

丝素蛋白用于血糖监测传感器的研究进展

糖尿病严重影响人们的日常生活,引起各种并发症,因此对糖尿病的控制和治疗尤为重要。血糖水平的日常监测对于糖尿病的有效管理起着重要作用。近几十年来血糖检测技术得到了快速发展,从取血式血糖仪到植入性可穿戴性血糖监测,血糖监测技术越来越成熟。丝素蛋白作为生物可降解材料,在血糖传感器的研究发展过程中发挥着重要的作用。讨论了各类血糖传感器的研究进展及存在的瓶颈问题,阐明了丝素蛋白材料在血糖传感器发展中的应用,并对丝素蛋白用于血糖监测未来发展进行了展望。     

手臂监测传感器的设计与验证

文章将人体手臂分为3个区域测试不同角度下每个区域的伸长率,确定了手臂皮肤伸长变化规律最显著的区域为II,理想状态下假设服装伸长与皮肤伸长同步,所以选择在第II区域即肘关节处设计传感器。制备了6种不同组织结构,不同横列数和相同纵行数的导电织物,测试了6种织物在纵向拉伸条件下的电阻变化,得到了导电织物的电阻随应变的变化规律,分析了组织结构和横列数不同对导电织物应变-电阻传感性能的影响,结果表明:导电织物选择采用横列数250纵行数80的2+2假罗纹结构,其线性拟合度和灵敏度最好。通过手臂弯曲实验验证了该针织柔性传感器及其测试系统的可行性。     

Environmental tobacco smoke as a source of polycyclic aromatic hydrocarbons in settled household dust

Environmental tobacco smoke is a major contributor to indoor air pollution. Dust and surfaces may remain contaminated long after active smoking has ceased (called 'thirdhand' smoke). Polycyclic aromatic hydrocarbons (PAHs) are known carcinogenic components of tobacco smoke found in settled house dust (SHD). We investigated whether tobacco smoke is a source of PAHs in SHD. House dust was collected from 132 homes in urban areas of Southern California. Total PAHs were significantly higher in smoker homes than nonsmoker homes (by concentration: 990 ng/g vs 756 ng/g, p = 0.025; by loading: 1650 ng/m(2) vs 796 ng/m(2), p = 0.012). We also found significant linear correlations between nicotine and total PAH levels in SHD (concentration, R(2) = 0.105; loading, R(2) = 0.385). Dust collected per square meter (g/m(2)) was significantly greater in smoker homes and might dilute PAH concentration in SHD inconsistently. Therefore, dust PAH loading (ng PAH/m(2)) is a better indicator of PAH content in SHD. House dust PAH loadings in the bedroom and living room in the same home were significantly correlated (R(2) = 0.468, p < 0.001) suggesting PAHs are distributed by tobacco smoke throughout a home. In conclusion, tobacco smoke is a source of PAHs in SHD, and tobacco smoke generated PAHs are a component of thirdhand smoke.     

以织物传感器为基础的呼吸监测方法

呼吸信号可以反映人体的生命现象和健康状况。由于可穿戴式呼吸测量装置能满足人们对于日常呼吸监测的需要而得到广泛的研究与应用。目前呼吸率测量的方法有许多种,其中已用在服装中的测试方法有电感应体积描记法、阻抗法、拉阻法、压电法。     

Effects of a chemical company fire on the occurrence of polycyclic aromatic hydrocarbons in plant foods

On Friday, September 1, 2006, the facilities of a chemicals distributor in the Spanish town of Caldas de Reis, were almost completely destroyed as a result of a fire. Comprehensive liquid chromatography-fluorescence detection (LC-FD) analyses were performed on plant foods to determine the toxic impact of this kind of accident on population. PAHs from a polluted atmosphere are generally transferred to plants by particle-phase deposition on the waxy leaf cuticle or by uptake in the gas phase through stomata. PAH levels in all samples were not alarming (total PAHs were below 4.240 ng/g) and the PAH profiles were similar, with the exception of peppers, in all vegetal materials (5-to-4 rings ratio of 1–2), suggesting the similarity in source type (the fire). PAH concentrations in plants were related to their surface exposed to air, indicating that the contribution of soil/water PAHs to plants (aerial part) accumulation was insignificant.     

化工厂环境监测技术的研究

长期以来,我国的经济发展以牺牲环境为代价,对生态造成严重的破坏.其中,化工厂生产带来的损害是不可逆的.随着我国对绿色可持续发展的重视程度不断提升,相关部门开始对相关的生产工作进行监控,降低污染,恢复生态环境.本文重点阐述化工厂环境监测技术,旨在为相关工作提供参考.     

Passive dosing of soil invertebrates with polycyclic aromatic hydrocarbons: limited chemical activity explains toxicity cutoff

The partitioning of organic soil pollutants into soil organisms is driven by their chemical activity, which normally does not exceed that of the pure pollutant. Passive dosing with the silicone poly(dimethylsiloxane) (PDMS) was used to initiate and maintain the maximum chemical activity of 10 polycyclic aromatic hydrocarbons (PAHs) in toxicity tests with the springtail Folsomia candida. The test animals could move freely on the PDMS saturated with PAHs, resulting in direct contact and exposure to saturated air. After 7 days, springtail lethality correlated neither with the octanol-water partition coefficients of the PAHs nor with their molecular size, but with their melting point All low-melting PAHs (T(M) < or = 110 degrees C) caused 100% lethality, whereas all high-melting PAHs (TM > or = 180 degrees C) caused no significant lethality. The lethality was successfully fitted to one chemical activity response curve for all PAHs tested, with effective chemical activity causing 50% lethality (Ea-50) of 0.058. It was also fitted to the PAH concentration in the PDMS, resulting in an EC(PDMS)-50 of 8.7 mM. Finally, the combined exposure to anthracene and pyrene was described by the sum of chemical activities causing lethality, in good agreement with the chemical activity-response curve obtained.     

Transponder-based sensor for monitoring electrical properties of biological cell solutions

An inductive passive remote sensor circuit for monitoring fermentation processes is presented. The sensor circuit consists of an interdigital capacitor and a planar coil structured on a glass laminated FR4-printed circuit board. This circuit resonates at frequencies between 2 and 4 MHz. After the resonant sensor circuit is immersed in a fermentation vessel with a cell solution, the resonant frequencies are detected by measuring the impedance of an external loop antenna. A new theory is presented to describe the behavior of the sensor circuit. In combination with a proposed equivalent circuit, the theory enables the calculation of the permittivity and conductivity of the cell solution under test by determining the resonant frequencies of the sensor without the need for any additional fitting functions. The influence of the relaxation behavior of living cells on the sensor signal with respect to the conductivity of the solution is discussed in detail. To prove the new theory, the determined permittivity is compared with the optical density of a cell solution, an indicator of cell concentration. The performed measurements show the expected correlation between the determined permittivity and optical density. The solution under test is a yeast culture in YPG medium.     

无线传感技术在粮食仓储环境监测中的应用

目的：解决无线传感器网络路由算法计算效率低、节能效果差等问题,建立一种新的无线传感器网络路由协议。方法：在粮食仓储环境监测系统的体系结构基础上,提出一种基于节点剩余能量分簇的节点调度方法用于粮食仓储环境监测的无线传感器网络;簇内活动节点数量从网络覆盖率和监控精度两个方面进行计算,根据节点的能量和分布对工作节点进行确定,并验证该节能策略的性能以及优越性。结果：与传统无线网络的路由协议相比,该协议的能耗显著降低,网络中各节点的能耗相对均匀并得到了有效平衡。结论：该方法提高了计算效率和降低了能耗,具有较好的调度效果。     

基于无线传感器网络的温室监测系统设计

运用传感器技术、计算机技术和通信技术，设计了用于温室环境参数检测的无线传感器网络监测系统．该系统以PIC单片机为无线传感器节点核心，配以高性能的传感器、检测电路以及数据传输的可靠性设计，实现了传感器节点与PC机的无线通信．实际运行情况表明：该系统实用性好，可靠性高，具有良好的应用前景．     

Freshness monitoring of sea bream (Sparus aurata) with a potentiometric sensor

Freshness in one of the main quality attributes for fish commercialization and consumption. The traditional method for fish freshness evaluation is sensory analysis. However, instrumental methods such as electrical, texture and colour measurements, image analysis, VIS spectroscopy and electronic noses have been widely studied as objective alternatives. Each of these methods has advantages and disadvantages, but none of them can be universally proposed for defining and measuring fish freshness.     

Membrane introduction mass spectrometry of nonpolar hydrocarbons using nitric oxide chemical ionization

Selectivity enhancement of membrane introduction mass spectrometry of nonpolar alkanes, alkenes, and aromatic hydrocarbons in air samples by application of nitric oxide chemical ionization (NOCI/MIMS) is demonstrated. Membrane methods are useful for separating compounds (usually nonpolar organics) from air and water samples without costly and time-consuming sample preparation, and coupled with mass spectrometry, they provide good sensitivity. But they often suffer from lack of specificity in mixture analysis, particularly for saturated organics. Nitric oxide chemical ionization is able to produce strong unique ion signals for many hydrocarbon test compounds that can be used to identify and quantify the parent neutrals. Our observed detection limits for a number of test compounds were relatively high; however, the method could potentially be useful for environmental analytical applications (e.g., plume tracking) if the monitored compound was at elevated levels or if NOCI/MIMS is coupled with a trapping method.