Nonenzymatic glucose sensing based on deposited palladium nanoparticles on epoxy-silver electrodes

A new approach for nonenzymatic glucose sensing, based on a simple modification of epoxy-silver surfaces deposited on the tip of commercial copper electric wires, is presented. Palladium was galvanically displaced on the surface of the epoxy-silver surface in order to obtain metal nanoparticles that act as catalyst for the direct oxidation of glucose. Scanning electron microscopy revealed the formation of the metal nanoparticles. X-ray photoelectron spectroscopy confirmed the metallic nature of the formed nanostructures on the surface. Electrochemical characterization and calibration of the palladium-modified epoxy-silver electrode is reported, obtaining a linear range of 1–20 mM for the detection of glucose with low interference of ascorbic acid and uric acid. A simple 3-step coulometry was used as the detection technique. The developed sensing material is believed to be a great candidate for integration in small devices for clinical essays, due to the simplicity and cost effectiveness of the presented approach, compared to the state-of-the-art devices reported recently in the literature. Simplicity in the coulometry determinations makes these Pd-modified epoxy-silver sensors a good candidate for easy glucose determinations.     

A system for ubiquitous fall monitoring at home via a wireless sensor network and a wearable mote

Accidental falls of our elderly, and physical injuries resulting, represent a major health and economic problem. Falls are the most common cause of serious injuries and are a major health threat in the stratum of older population. Early detection of a fall is a key factor when trying to provide adequate care to elderly person who has suffered an accident at home. Therefore, the detection of falls in the elderly remains a major challenge in the field of public health. Specific actions aimed at the fall detection can provide urgent care which allows, on the other hand, drastically reduce the cost of medical care, and improve primary care service. In this paper, we present a support system for detecting falls of an elder person by the combination of a wearable wireless sensor node based on an accelerometer and a static wireless non-intrusive sensory infrastructure based on heterogeneous sensor nodes. This previous infrastructure called DIA (Dispositivo Inteligente de Alarma, in Spanish) is an AAL (Ambient Assisted Living) system that allows to infer a potential fall. This inference is reinforced for prompt attention by a specific sensorisation at portable node sensor in order to help distinguish between falls and daily activities of assisted person. The wearable node will not determine a falling situation, it will advice the reasoner layer about specific acceleration patterns that could, eventually, imply a falling. Is at the higher layer where the falling is determined from the whole context produced by mesh of fixed nodes. Experimental results have shown that the proposed system obtains high reliability and sensitivity in the detection of the fall.     

Use of Sodium Alginate-Poly(vinyl pyrrolidone) Membranes for Pervaporation Separation of Acetone/Water Mixtures

Pervaporative separation of acetone from water at a concentration range of 0–100 wt% were studied using sodium alginate (NaAlg)/Poly vinyl pyrrolidone (PVP) membranes. Membranes were prepared in different ratios (w/w) (100/0, 95/5, 90/10, 85/15, 80/20, 75/25) of NaAlg/PVP by crosslinking with CaCl₂. Experimental studies were carried out to investigate the effects of the operating temperature, feed composition, and membrane thickness on the pervaporation performance. The optimum operating temperature, membrane thickness, NaAlg/PVP ratio, and feed composition were determined as 40°C, 70 µm, 75/25 (w/w), and 20 wt% acetone, respectively. The effect of PVP content in the membranes was investigated on pervaporation performance. The permeation rate was increased with increasing the PVP content; however, there was no appreciable change about the separation factor. The permeation rate and separation factor values were found to be in the range of 0.304–1.023 kg/m² h and 16–57, respectively. In addition, the sorption-diffusion properties of the alginate membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was the dominant factor for the separation of acetone/water mixtures.     

烟用二醋酸纤维纺丝丙酮/空气混合气(VLA)高浓度控制及其应用

丙酮/空气混合气(VLA)中丙酮浓度是烟用二醋酸纤维丝束生产的一个重要工艺参数。文章以理论计算为指导,从干燥机VLA和纺丝机VLA丙酮浓度两方面,介绍了提高丙酮浓度的可行性,和高丙酮浓度运行下的控制方法。运行结果显示,在保证安全的前提下,提高纺丝VLA浓度,丙酮回收所需的蒸汽消耗显著降低,生产运营成本降低。     

An enzyme sensor for the determination of total amines in dry-fermented sausages

An enzyme sensor employing diamine oxidase from porcine kidney in combination with an oxygen electrode has been developed and optimised to estimate the content of total amines in dry-fermented sausages. The enzyme DAO was immobilised on a preactivated Immunodyne membrane using glutaraldehyde as cross-linking agent. The enzymatic determination was based on the measurement of the consumed O₂ in a platinum electrode poised at −600 mV versus Ag/AgCl. The reaction was started by the direct injection of either the standard or meat extract on the enzymatic membrane. The immobilised enzyme could be used up to 30 analyses along the day without significant loss of sensitivity and could be stored at 4 °C showing good stability for at least 6 weeks. A good correlation was observed when comparing data obtained with the enzyme sensor to those obtained with a standard HPLC method. Thus, this sensor may be a reliable screening method to detect the presence of biogenic amines in dry-fermented sausages that can constitute a useful tool for quality control in the meat industry.     

Enhancement of sensitivity of glucose sensors from alizarin–boronic acid adducts in aqueous micelles

The sensitivity of glucose sensors fabricated from alizarin–boronic acid adducts was improved by an assistance of surfactants. Basically, Alizarin Red S (ARS) is not a fluorescence active compound. However, the fluorescence emission can be observed when forming an adduct with 2-formylphenyl boronic acid (2-FPBA). Using displacement strategy, the fluorescence intensity of the ARS/2-FPBA adduct decreased as a linear function of the glucose concentration. A simple and sensitive method was developed by incorporating the ARS/2-FPBA adduct in the hydrophobic core of micelles. Various parameters that could possibly affect the fluorescence quenching ability including solution pH, concentration of 2-FPBA, types of surfactants and concentrations of surfactants were investigated. The optimum condition for the determination of glucose by the proposed assay was 2 mM cetyltrimethylammonium bromide (CTAB) in 0.05 M phosphate buffer pH 7.0. The fluorescence intensity of the ARS/2-FPBA adduct in the presence of CTAB was remarkably 13 times higher than that in the buffer solution. Moreover, the linear working concentration range was found to be 1.2–80 mM, and the calibration sensitivity was 14 times higher than that from the system containing only buffer solution.     

钼铁矿自动化计量机械系统改进设计与应用

针对原有大颗粒、高比重钼铁矿计量机械部分由于设计缺陷导致的各称重传感器受力不均衡、精度不高、称重偏差较大、自动化程度相对较低等问题,结合生产工艺条件,综合利用静态称重的低成本、高精度与动态称重的高效率优点,对称体结构进行优化设计。节约了成本,降低了操作人员的劳动强度,提高了生产效率,满足了生产需求。     

矿井提升钢丝绳应变式张力传感器解耦研究

矿井提升钢丝绳张力监测系统中,应变式传感器在动载工况下的真实纵向力很难准确计算和分离。为了克服这一难题,结合大载荷低高度的传感器安装条件和结构特点,进行了实验研究,采用最小二乘法和独立成分法对比分析了传感器纵向受力工况下静态解耦效果,结果表明,Z方向与X,Y方向和MZ的静态解耦耦合率值均较小,独立成分为0.01%,最小二乘法为1%;采用对角优势化补偿法和独立成分法进行了动态解耦研究,结果表明,两者对维间耦合的影响均满足要求,但对角优势化补偿法补偿后的输出信号幅值稳定在0.9左右,而独立成分法补偿后的输出信号幅值则稳定在1.0左右。研究结果表明,采用独立成分理论计算和提取矿井多绳提升钢丝绳应变式张力传感器纵向力具有较高精度,接近完成解耦。     

电容式水位传感器在柔性承载板载荷试验中的应用

介绍了柔性承载板的构造要求,并对电容式水位传感器的原理、制作与标定方法进行了探讨,指出将电容式水位传感器应用于柔性承载板载荷试验中,通过向囊内泵入空气,确保了水囊高度和底面积不变,保证了载荷试验结果的准确性。     

电感式位移传感器在柔性承载板载荷试验中应用

为了解决平板载荷试验测试结果不准确的问题,设计了柔性承载板,提出了采用电感式位移传感器测试板底不同位置沉降的方法,通过仪器制作、标定及实验测试,证明了该方法的可行性和准确性。