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Good Signal (good + signal)
Selected AbstractsAmperometric Glucose Biosensors Based on Glassy Carbon and SWCNT-Modified Glassy Carbon ElectrodesELECTROANALYSIS, Issue 1 2008Irene Carpani Abstract Different carbonaceous materials, such as single-walled carbon nanotubes (SWCNTs) and glassy carbon submitted to an electrochemical activation at +1.80,V (vs. SCE) for 900,s, have been used with the aim of comparing their performances in the development of enzyme electrodes. Commercial SWCNTs have been pretreated with 2.2,M HNO3 for 20,h prior to use. The utility of activated GC as promising material for amperometric oxidase-based biosensors has been confirmed. With glucose oxidase (GOx) as a model enzyme, glucose was efficiently detected up to 1 mM without the use of a mediator. Both electrodes operated in stirred solutions of 0.1,M phosphate buffer (pH,5.5), containing dissolved oxygen, at a potential of ,0.40,V vs. SCE. Although the performances of the two carbonaceous materials were comparable, the biosensors based on activated GC were characterized by a practically unchanged response 40 days after the fabrication, a better signal to noise ratio, and a little worse sensitivity. In addition, the preparation procedure of such biosensors was more simple, rapid and reproducible. [source] Optimization of a multiphase sensor for detection of phosphonates in airAICHE JOURNAL, Issue 1 2010Chelsea N. Monty Abstract The objective of this article is to report the modeling and optimization of a new MEMS-based phosphonate sensor that utilizes a porous membrane between a gas and a liquid stream to allow operation at low-liquid and high-gas flow rates. Previous work from our laboratory demonstrated that phosphonate molecules can be detected with such a device, but the sensitivity was insufficient for certain applications (e.g., detection of pesticides in foodstuffs). In this article, COMSOL simulations and design of experiments were used to optimize the device. We find that both the simulation and the experiment show that (i) the size of the pores in the membranes and (ii) the liquid channel height make the most difference to the sensor response. Also, by optimizing the geometry, the sensitivity of the device could be enhanced. The optimized device can detect 109 molecules with good signal to noise. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Measurement of cardiac output in normal pregnancy by a non-invasive two-dimensional independent Doppler deviceAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 2 2009Catharina C. M. KAGER Aims: To compose a normogram regarding cardiac output during pregnancy measured with ultrasonic cardiac output monitor (USCOM), a non-expensive simple continuous wave Doppler device and to investigate if this machine could be useful for haemodynamic monitoring during pregnancy. Methods: Cardiac output was measured in 172 pregnant women with a gestational age < 21 weeks (n = 59), 21,32 weeks (n = 48), and > 32 weeks' gestation (n = 48). Interobserver differences were determined by measuring 24 patients and comparing results between three different observers. Results: A good signal could be obtained in 155 (90.2%) pregnant women. Haemodynamic profiles were in line with data published in the literature. In 9.8 % of cases it was difficult to get a good result. Interobserver variations between the research officer (CK) and two clinicians were good (r = 0.9359 and r = 0.9609). Conclusion: USCOM appears to be a reliable and fast method to measure cardiac output compared with existing highly complex ultrasounds machines used in cardiology. It is easy to learn, cheap and quite reproducible between different observers. Further research is required to define its place in the management of hypertensive complications during pregnancy. [source] Design of a complement mannose-binding lectin pathway-specific activation system applicable at low serum dilutionsCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2006M. Harboe Summary Recently we showed that alternative pathway (AP) amplification was responsible for more than 80% of specific classical pathway-induced terminal pathway activation under physiological conditions. The present study aimed to design a system for specific lectin pathway (LP) activation applicable at low serum dilutions with a fully functional AP. Comparison between activation of normal human serum (NHS), a mannose-binding lectin (MBL) homozygous D/D -deficient serum, and sera deficient in C1q and C2, all diluted 1 : 2, was essential to document optimal conditions for LP specificity. Mannan on the solid phase of enzyme-linked immunosorbent assay (ELISA) plates was used for activation, showing 0·5 µg mannan/well to give optimal conditions because at this concentration a good signal was preserved for C4 and TCC deposition in NHS, whereas the C3 deposition observed in C2-deficient serum at higher mannan concentrations reached nadir at 0·5 µg/well, indicating a lack of direct AP activation under these conditions. Pooled NHS and C1q-deficient serum gave the same degree of C4 and terminal complement complex (TCC) deposition, whereas deposition of these products was not obtained with MBL-deficient serum. Reconstitution with purified MBL, however, restored the depositions. A blocking anti-MBL monoclonal antibody (mAb) completely abolished the complement deposition, in contrast to a non-inhibiting anti-MBL mAb. Activation of C2-deficient serum induced C4 deposition similar to NHS, but negligible deposition of C3 and TCC, confirming the lack of direct activation of AP. Thus, this assay is unique in being LP-specific at low serum dilution and thus particularly suitable to study LP activation mechanisms and the role of AP amplification under physiological conditions. [source] | |||||||||||||