Fast Response (fast + response)

Distribution by Scientific Domains

Terms modified by Fast Response

  • fast response time

  • Selected Abstracts


    Fast response 'saves AVA

    AUSTRALIAN VETERINARY JOURNAL, Issue 12 2000
    Article first published online: 10 MAR 200
    No abstract is available for this article. [source]


    Ammonia Gas Sensor Using Polypyrrole-Coated TiO2/ZnO Nanofibers

    ELECTROANALYSIS, Issue 12 2009
    Ying Wang
    Abstract Highly porous polypyrrole (PPy)-coated TiO2/ZnO nanofibrous mat has been successfully synthesized. The core TiO2/ZnO nanofibers have an average diameter of ca. 100,nm and the shell of ultrathin PPy layer has a thickness of ca. 7,nm. The NH3 gas sensor using the as-prepared material exhibited a fast response over a wide dynamic range and high sensitivity with a detection limit of 60,ppb (S/N=3). Compared to conventional pristine PPy film, the improved performance in NH3 detection can be attributed to the free access of NH3 to PPy and a minimized gas diffusion resistance through the ultrathin PPy layer. [source]


    Synthesis and Characterization of MWNTs/Au NPs/HS(CH2)6Fc Nanocomposite: Application to Electrochemical Determination of Ascorbic Acid

    ELECTROANALYSIS, Issue 16 2008
    Jian-Ding Qiu
    Abstract In this article, a detailed electrochemical study of a novel 6-ferrocenylhexanethiol (HS(CH2)6Fc) self-assembled multiwalled carbon nanotubes-Au nanoparticles (MWNTs/Au NPs) composite film was demonstrated. MWNTs/Au NPs were prepared by one-step in situ synthesis using linear polyethyleneimine (PEI) as bifunctionalizing agent. HS(CH2)6Fc, which acted as the redox mediator, was self-assembled to MWNTs/Au NPs via Au-S bond. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier transformed infrared absorption spectroscopy (FT-IR), UV-visible absorption spectroscopy, and cyclic voltammetry were used to characterize the properties of the MWNTs/Au NPs/HS(CH2)6Fc nanocomposite. The preparation of the nanocomposite was very simple and effectively prevented the leakage of the HS(CH2)6Fc mediator during measurements. The electrooxidation of AA could be catalyzed by Fc/Fc+ couple as a mediator and had a higher electrochemical response due to the unique performance of MWNTs/Au NPs. The nanocomposite modified electrode exhibited excellent catalytic efficiency, high sensitivity, good stability, fast response (within 3,s) and low detection limit toward the oxidation of AA at a lower potential. [source]


    Lead(II) Potentiometric Sensor Based on 1,4,8,11-Tetrathiacyclotetradecane Neutral Carrier and Lipophilic Additives

    ELECTROANALYSIS, Issue 11 2008
    Mohamed
    Abstract A potentiometric sensor for lead(II) ions based on the use of 1,4,8,11-tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis-(p -chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10,5,1.0×10,2,mol L,1 with a Nernstian slope of 29.9,mV decade,1 and a lower limit of detection of 2.2×10,6,mol L,1 Pb(II) ions over the pH range of 3,6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS. [source]


    A Novel Al(III)-Selective Electrochemical Sensor Based on N,N,-Bis(salicylidene)-1,2-phenylenediamine Complexes

    ELECTROANALYSIS, Issue 16 2006
    B. Gholivand
    Abstract A polyvinylchloride membrane sensor based on N,N,-bis(salecylidene)-1,2-phenylenediamine (salophen) as membrane carrier was prepared and investigated as a Al3+ -selective electrode. The sensor exhibits a Nernstian response toward Al(III) over a wide concentration range (8.0×10,7,3.0×10,2,M), with a detection limit of 6.0×10,7,M. The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 3.2,4.5. The electrode possesses advantages of very fast response and high selectivity for Al3+ in comparison with alkali, alkaline earth and some heavy metal ions. The sensor was used as an indicator electrode, in the potentiometric titration of aluminum ion and in determination of Al3+ contents in drug, water and waste water samples. [source]


    Aluminum(III) Porphyrins as Ionophores for Fluoride Selective Polymeric Membrane Electrodes

    ELECTROANALYSIS, Issue 6 2006
    Jeremy
    Abstract Aluminum(III) porphyrins are examined as potential fluoride selective ionophores in polymeric membrane type ion-selective electrodes. Membranes formulated with Al(III) tetraphenyl (TPP) or octaethyl (OEP) porphyrins are shown to exhibit enhanced potentiometric selectivity for fluoride over more lipophilic anions, including perchlorate and thiocyanate. However, such membrane electrodes display undesirable super-Nernstian behavior, with concomitant slow response and recovery times. By employing a sterically hindered Al(III) picket fence porphyrin (PFP) complex as the membrane active species, fully reversible and Nernstian response toward fluoride is achieved. This finding suggests that the super-Nernstian behavior observed with the nonpicket fence metalloporphyrins is due to the formation of aggregate porphyrin species (likely dimers) within the membrane phase. The steric hindrance of the PFP ligand structure eliminates such chemistry, thus leading to theoretical response slopes toward fluoride. Addition of lipophilic anionic sites into the organic membranes enhances response and selectivity, indicating that the Al(III) porphyrin ionophores function as charged carrier type ionophores. Optimized membranes formulated with Al(III)-PFP in an o -nitrophenyloctyl ether plasticized PVC film exhibit fast response to fluoride down to 40,,M, with very high selectivity over SCN,, ClO4,, Cl,, Br, and NO3, (kpot<10,3 for all anions tested). With further refinements in the membrane chemistry, it is anticipated that Al(III) porphyrin-based membrane electrodes can exhibit potentiometric fluoride response and selectivity that approaches that of the classical solid-state LaF3 crystal-based fluoride sensor. [source]


    Mixed Aza-Thioether Crowns Containing a 1,10-Phenanthroline Sub-Unit as Neutral Ionophores for Silver Ion

    ELECTROANALYSIS, Issue 24 2002
    Mojtaba Shamsipur
    Abstract Three different recently synthesized aza-thioether crowns containing a 1,10-phenanthroline sub-unit (L1,L3) and a corresponding acyclic ligand (L4) were studied to characterize their abilities as silver ion ionophores in PVC-membrane electrodes. Novel conventional silver-selective electrodes with internal reference solution (CONISE) and coated graphite-solid contact electrodes (SCISE) were prepared based on one of the 15-membered crowns containing two donating S atoms and two phenanthroline-N atoms (L1). The electrodes reveal a Nernstian behavior over wide Ag+ ion concentration ranges (1.0×10,5,1.0×10,1,M for CONISE and 5.0×10,8,4.0×10,2,M for SCISE) and very low limits of detection (8.0×10,6,M for CONISE and 3.0×10,8,M for SCISE). The potentiometric response is independent from pH of the solution in the pH range 3.0,8.0. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations. The electrodes can be used for at least 2 months (for CONISE) and 4 months for (SCISE) without any appreciable divergence in potentials. The electrodes were used as an indicator electrode in the potentiometric titration of Ag+ ion and in the determination of silver in photographic emulsions and in radiographic and photographic films. [source]


    Monitoring of Machining Processes Using Sensor Equipped Tools,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2010
    Ekkard Brinksmeier
    A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By this way, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350,°C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set-up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains. [source]


    Sprinklered office fire tests

    FIRE AND MATERIALS, Issue 3 2008
    I. D. Bennetts
    Abstract This paper presents data relating to the performance of sprinklers and detectors in real office fire situations. For sprinklers, these data are additional to that associated with the standardized testing used to determine the design delivery density and pressure requirements for various occupancy situations, and provide a useful insight into the effect of sprinklers on developing fires with various office situations. The data given in this paper include the times for activation of various types of sprinkler heads (normal and fast response), the efficacy of the systems as far as extinguishment is concerned, estimates of the maximum size of the fires prior to commencement of extinguishment and associated air temperatures at various locations within the office enclosures. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Toward a More Embedded Production System?

    GROWTH AND CHANGE, Issue 3 2009
    Automotive Supply Networks, Localized Capabilities in Poland
    ABSTRACT The article addresses the embeddedness of automotive production in Poland in terms of supply networks. A comprehensive analysis of more than 550 suppliers, supported by company interviews, shows that foreign-owned producers become embedded in Poland in the automotive supplier networks they have largely created themselves. Numerous local suppliers gain access to export markets and become integrated in a Europe-wide production system. This trend has been accompanied by significant upgrading of foreign affiliates and domestic firms in terms of product quality, cost efficiency, adaptability, and fast response, but far less in nonproduction competences such as R&D. It is argued that the competences of automotive suppliers in Poland are built upon the localized capabilities, which are a product of the dynamic interplay between the activity of foreign firms and the changing local environment comprising various stakeholders. The localized capabilities constitute elements of a company's sunk costs and are embedding automotive producers in Poland. At the same time, the dependence on decisions and innovations from abroad and the limited development of local design and brands may constrain the future role of suppliers from the semiperipheral economy of Poland. [source]


    Accuracy and precision of different sampling strategies and flux integration methods for runoff water: comparisons based on measurements of the electrical conductivity

    HYDROLOGICAL PROCESSES, Issue 2 2006
    Patrick Schleppi
    Abstract Because of their fast response to hydrological events, small catchments show strong quantitative and qualitative variations in their water runoff. Fluxes of solutes or suspended material can be estimated from water samples only if an appropriate sampling scheme is used. We used continuous in-stream measurements of the electrical conductivity of the runoff in a small subalpine catchment (64 ha) in central Switzerland and in a very small (0·16 ha) subcatchment. Different sampling and flux integration methods were simulated for weekly water analyses. Fluxes calculated directly from grab samples are strongly biased towards high conductivities observed at low discharges. Several regressions and weighted averages have been proposed to correct for this bias. Their accuracy and precision are better, but none of these integration methods gives a consistently low bias and a low residual error. Different methods of peak sampling were also tested. Like regressions, they produce important residual errors and their bias is variable. This variability (both between methods and between catchments) does not allow one to tell a priori which sampling scheme and integration method would be more accurate. Only discharge-proportional sampling methods were found to give essentially unbiased flux estimates. Programmed samplers with a fraction collector allow for a proportional pooling and are appropriate for short-term studies. For long-term monitoring or experiments, sampling at a frequency proportional to the discharge appears to be the best way to obtain accurate and precise flux estimates. Copyright © 2006 John Wiley & Sons, Ltd. [source]


    Fast High-Temperature Response of Carbon Nanotube Film and Its Application as an Incandescent Display

    ADVANCED MATERIALS, Issue 35 2009
    Peng Liu
    Super aligned carbon nanotube (CNT) film shows a fast high-temperature response: the film can be heated to incandescence and cools down in about 1 ms. Using screen printing and laser cutting, an incandescent CNT film array that can dynamically display Chinese characters is fabricated. More applications of the film may be developed based on its fast response. [source]


    Synthesis of pH dependent chitosan-EPI hydrogel films and their application for in vitro release of promethazine hydrochloride

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
    Yolda
    Abstract Chitosan-epichlorohydrin hydrogel films (ChitEPI) were synthesized by using chitosan in the presence of epichlorohydrin (EPI) as a crosslinking agent at various amounts. SEM, FTIR, TGA, and DSC analysis were conducted for the characterization of the hydrogels. The DSC measurements indicate that ChitEPI hydrogels did not exhibit better thermal stability when compared to chitosan. Swelling behavior of Chitosan-EPI hydrogel film is pH dependent and showed a reversible swelling behavior with a fast response. The hydrogels were used for in vitro release of promethazine hydrochloride (PHCl) in pH = 1.2 and pH = 7.4 phosphate buffer solutions (PBS). The release of PHCl synthesized from hydrogels at pH = 7.4 is quite low while at pH = 1.2, the highest value was observed as 49% for ChitEPI600. It has been also found that PHCl release from ChitEPI thin films is mainly controlled by diffusion control mechanism. ChitEPI hydrogels may be used for the delivery of drug in stomach and gastrointestinal tract. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


    Preparation and optical properties of an all-polymer light modulator using colored N -isopropylacrylamide gel particles in a gel-in-gel system

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
    Hiroaki Tsutsui
    Abstract A novel all-polymer light modulator with a gel-in-gel system was developed. The gel-in-gel system was constructed with colored gel particles responsive to stimuli held independently in another stimuli-nonresponsive gel matrix. Well-known thermoresponsive N -isopropylacrylamide (NIPAM) gel particles containing a pigment were dispersed and fixed in an outer stimuli-nonresponsive gel matrix. When poly(vinyl alcohol),styrylpyridinium (PVA,SbQ) was used for the outer gel matrix, the light modulator showed excellent color-changing properties because the PVA,SbQ matrix was selectively formed around the NIPAM gel particles and the particles exhibited a large volume change in the matrix. The temperature when the outer gel matrix was formed affected the haze of the light modulator. When the outer gel matrix was formed in the swollen state of the NIPAM gels, the haze of a light modulator increased with heating. On the contrary, the haze of a light modulator prepared in the shrunken state of the NIPAM gels decreased with heating. The response time of the color change was less than 1 s. The gel-in-gel system made a very fast macroscopic color change, taking advantage of the fast response of the micrometer-sized gel particles. We believe that a light modulator with a gel-in-gel system may find various applications in optical devices. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2295,2303, 2007 [source]


    Flow-injection,chemiluminescence method for the determination of penicillin G potassium

    LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4-5 2005
    Wei Cao
    Abstract The degradation product of penicillin G potassium can react with potassium permanganate in acidic medium and produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow-injection system. The experiments indicated that under optimum conditions, the chemiluminescence intensity was linearly related to the concentration of penicillin G potassium within the range 1.0 × 10,7,1.0 × 10,5 g/mL, with a detection limit (3,) of 7 × 10,8 g/mL. The relative standard deviation was 1.0% for 4.0 × 10,7 g/mL penicillin G potassium solution (n = 11). This method has the advantages of simple operation, fast response and high sensitivity. The method was successfully applied to the analysis of penicillin G potassium in raw medicines. Copyright © 2005 John Wiley & Sons, Ltd. [source]


    Flow injection,chemiluminescence determination of amoxycillin using potassium permanganate and formaldehyde system

    LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2005
    Wei Cao
    Abstract It was found that amoxycillin can react with potassium permanganate in an acidic medium to produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow-injection system. The experimental results indicate that, under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of amoxycillin in the range 5.48 × 10,8,2.74 × 10,6 mol[sol ]L, with a detection limit (3,) of 4.1 × 10,8 mol[sol ]L. The relative standard deviation was 1.0% at 1.1 × 10,6 mol[sol ]L amoxycillin (n = 11 measurements). This method has the advantages of high sensitivity, fast response and ease of operation. The method was successfully applied to the determination of amoxycillin in raw medicines and capsules. Copyright © 2005 John Wiley & Sons, Ltd. [source]


    Shrinking Behavior of Surfactant-Grafted Thermosensitive Gels and the Mechanism of Rapid Shrinking

    MACROMOLECULAR RAPID COMMUNICATIONS, Issue 11 2008
    Kosuke Okeyoshi
    Abstract Surfactant-grafted hydrogels with a fast response to temperature were prepared. In order to clarify the mechanism of rapid shrinking, the effects of the grafted surfactant and the homogeneity of the main chain were investigated. Poly(NIPAAm- co -S180A) gels prepared using a chemical cross-linker (bis-PNS gels) exhibited rapid shrinking, as did PNS gels prepared by , -ray irradiation (, -PNS gels). This suggested that the rapid shrinking of the PNS gel did not depend on the homogeneity of the main-chain structure. The shrinking kinetics of the bis-PNS gels depended on the amount of the introduced surfactant, which means that shrinking is enhanced by micelle formation as a dynamic driving force. From the analysis by dynamic light scattering (DLS) and scanning microscopic light scattering (SMILS), it was suggested that the micelle structure, which induced rapid shrinking, existed in the bis-PNS gel. [source]


    Synthesis of azobenzene-functionalized two-arm, three-arm and four-arm telomers using polyfunctional chain transfer agents

    POLYMER INTERNATIONAL, Issue 11 2009
    Md Zahangir Alam
    Abstract BACKGROUND: Star-shaped polymers are very attractive because of their interesting properties such as reduced viscosity, good solubility, low glass transition temperature and fast response to external stimuli. The incorporation of azobenzene moieties in star-shaped polymers could significantly widen their potential applications in various optical devices. One of the most important properties of the azobenzene chromophore is its reversible trans,cis photoisomerization induced by UV or visible light. Photoisomerization induces conformational changes in azopolymer chains, which in turn lead to macroscopic variations in chemical and physical properties of the surroundings and media. RESULTS: This study reports the synthesis of azobenzene-functionalized two-, three- and four-arm telomers via free radical telomerization using the di-, tri- and tetrafunctional chain transfer agents 1,2- and 1,4-benzenedimethanethiol, trimethylolpropane-tris(2-mercaptoacetate) and pentaerythritol-tetrakis(3-mercaptopropionate), respectively, in the presence of azobisisobutyronitrile. Azotelomers were characterized using gel permeation chromatography and 1H NMR and Fourier transform infrared spectroscopy. Thermal phase transition behaviors were investigated using differential scanning calorimetry and polarized optical microscopy. Azotelomers synthesized in this study showed reversible photoisomerization and a fast generation of birefringence. CONCLUSION: Considering the photoisomerization behavior and birefringence of the two-, three- and four-arm azotelomers, it can be concluded that they could be potential candidates for use in various optical devices. Copyright © 2009 Society of Chemical Industry [source]


    Synthesis of pH-responsive crosslinked poly[styrene- co -(maleic sodium anhydride)] and cellulose composite hydrogel nanofibers by electrospinning

    POLYMER INTERNATIONAL, Issue 5 2009
    Shengguang Cao
    Abstract BACKGROUND: Stimuli-sensitive materials show enormous potential in the development of drug delivery systems. But the low response rate of most stimuli-sensitive materials limits their wider application. We propose that electrospinning, a technique for the preparation of ultrafine fibrous materials with ultrafine diameters, may be used to prepare materials with a fast response to stimuli. RESULTS: Poly[styrene- co -(maleic sodium anhydride)] and cellulose (SMA-Na/cellulose) hydrogel nanofibers were prepared through hydrolysis of precursor electrospun poly[styrene- co -(maleic anhydride)]/cellulose acetate (SMA/CA) nanofibers. In the presence of diethylene glycol, the SMA/CA composite nanofibers were crosslinked by esterification at 145 °C, and then hydrolyzed to yield crosslinked SMA-Na/cellulose hydrogel nanofibers. These nanofibers showed better mechanical strengths and were pH responsive. Their water swelling ratio showed a characteristic two-step increase at pH = 5.0 and 8.2, with the water swelling ratio reaching a maximum of 27.6 g g,1 at pH = 9.1. CONCLUSION: The crosslinked SMA-Na hydrogel nanofibers supported on cellulose showed improved dimensional stability upon immersion in aqueous solutions. They were pH responsive. This new type of hydrogel nanofiber is a potential material for biomedical applications. Copyright © 2009 Society of Chemical Industry [source]


    Glucose oxidase electrodes of polyaniline, poly(o -toluidine) and their copolymer as a biosensor: a comparative study

    POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2004
    D. D. Borole
    Abstract A simple technique is described for constructing a glucose sensor by the entrapment of glucose oxidase (GOD) in a polyaniline (PA), poly(o -toluidine) (POT) and their copolymer poly(aniline-co- o -toluidine) (PA-co-POT) thin films, which were electrochemically deposited on a platinum plate in phosphate and acetate buffer. The maximum current response was observed for PA, POT, and PA-co-POT GOD electrodes at pH 5.5 and potential 0.60,V (v. Ag/AgCl). The phosphate buffer gives fast response as compared to acetate buffer in amperometric measurements. PA GOD electrode shows the fastest response followed by PA-co-POT and POT GOD electrodes. Copyright © 2004 John Wiley & Sons, Ltd. [source]


    Gender differences in behavioral inhibitory control: ERP evidence from a two-choice oddball task

    PSYCHOPHYSIOLOGY, Issue 6 2008
    Jiajin Yuan
    Abstract The inhibition of inappropriate behaviors is important for adaptive living in changing environments. The present study investigated gender-related behavioral inhibitory control by recording event-related potentials for standard and deviant stimuli while subjects performed a standard/deviant distinction task by accurately pressing different keys within 1000 ms. The results showed faster reaction times (RTs) for deviant stimuli in women than in men, although RTs for standard stimuli were similar across genders. There were significant gender and stimulus interaction effects on mean amplitudes during each of the 170,230-ms, 250,330-ms, and 350,600-ms intervals, and women exhibited shorter latencies and larger amplitudes than men at deviant-related P2, N2, and P3 components. As an accurate, fast response to the rare deviant stimuli involves behavioral inhibitory control on the prepotent response whereas the response to the standard stimuli does not, it is clear that there is a general gender difference in behavioral control for human adults. This may relate to differential inhibitory demands by each gender during evolution. [source]


    System aspects of the EUDOXOS observatories network

    ASTRONOMISCHE NACHRICHTEN, Issue 8 2006
    N. H. Solomos
    Abstract The networking architecture of the EUDOXOS' robotic telescopes is presented. We have studied adopted and tested various software & hardware approaches for developing an observational facility equipped with the very high availability needed to achieve continuous operation, inherent capacity for effective multiuser support, fully robotic unattended operation, fast response to targets of opportunity and accommodation of tele-operating instruments. Critical practical aspects and considerations of our operating implementation as well as the main points of an ongoing upgrade initiative expected to be of general interest, are discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    A New Amperometric Biosensor Based on HRP/Nano-Au/L -Cysteine/Poly(o -Aminobenzoic acid)-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

    CHINESE JOURNAL OF CHEMISTRY, Issue 11 2006
    Ming-Yu Tang
    Abstract The third generation amperometric biosensor for the determination of hydrogen peroxide (H2O2) has been described. For the fabrication of biosensor, o -aminobenzoic acid (oABA) was first electropolymerized on the surface of platinum (Pt) electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase (HRP) absorbed by nano-scaled particulate gold (nano-Au) was immobilized on the electrode modified with polymerized o -aminobenzoic acid (poABA) with L -cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of +20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10,6 to 3.55×10,3 mol·L,1 to H2O2 with a sensibility of 0.0177 A·L,1·mol,1 and a detection limit (S/N=3) of 4.3×10,7 mol·L,1. The biosensor demonstrated a 95% response within less than 10 s. [source]


    Adaptive repetitive control for resonance cancellation of a distributed solar collector field

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2009
    J. D. Álvarez
    Abstract This paper deals with modelling and control of the outlet temperature in a distributed solar collector field. The resonance dynamics characteristics of this kind of system are similar to those of tubular heat exchangers in the closed-loop system bandwidth when fast responses are required. Simple low-order rational models are unable to capture the resonance dynamics, which can be excited by changes in both the heat transfer fluid flow and solar irradiation. This paper proposes a new model derived from a similar model for a tubular heat exchanger. This model allows the use of low-order controllers, which can be extended to an adaptive control scheme to account for varying resonance frequencies, as a new functionality achieving fast, well-damped responses. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    High-sensitive neural network ammonia sensor based on shear horizontal surface acoustic wave devices

    JOURNAL OF CHEMOMETRICS, Issue 10 2008
    Chi-Yen Shen
    Abstract In this paper, a shear horizontal surface acoustic wave devices coated with L-glutamic acid hydrochloride were applied as ammonia sensors. This sensor has shown high sensitivity and fast responses to ppb-level ammonia. The frequency shift linearly increased as the ammonia concentration increased from 40 to 400,ppb in dry environment. In the humid environment, the frequency shift gradually decreased with ammonia concentration increasing. In order to precisely estimate the ammonia in humid environment, two different neural models, the conventional feedforward neural network and quantum neural network, were used as the identifier and their performances were reported and compared. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Mimosa pudica: Electrical and mechanical stimulation of plant movements

    PLANT CELL & ENVIRONMENT, Issue 2 2010
    ALEXANDER G. VOLKOV
    ABSTRACT Thigmonastic movements in the sensitive plant Mimosa pudica L., associated with fast responses to environmental stimuli, appear to be regulated through electrical and chemical signal transductions. The thigmonastic responses of M. pudica can be considered in three stages: stimulus perception, electrical signal transmission and induction of mechanical, hydrodynamical and biochemical responses. We investigated the mechanical movements of the pinnae and petioles in M. pudica induced by the electrical stimulation of a pulvinus, petiole, secondary pulvinus or pinna by a low electrical voltage and charge. The threshold value was 1.3,1.5 V of applied voltage and 2 to 10 µC of charge for the closing of the pinnules. Both voltage and electrical charge are responsible for the electro-stimulated closing of a leaf. The mechanism behind closing the leaf in M. pudica is discussed. The hydroelastic curvature mechanism closely describes the kinetics of M. pudica leaf movements. [source]


    Preparation, morphology and pH sensitivity of hybrid hydrolyzed polyacrylonitirile- blend -gelatin hydrogel fibers

    POLYMER INTERNATIONAL, Issue 9 2008
    Liwei Yu
    Abstract BACKGROUND: Polyacrylonitrile (PAN) artificial muscles have attracted considerable attention for their fast responses. This research work is based on the preparation of novel pH-sensitive hydrogel fibers derived from hydrolyzed PAN and gelatin by wet spinning and chemical modification. RESULTS: Through characterization of the fiber dynamic and static pH-sensitive behavior, pH response times were found to improve greatly with increasing gelatin content. At a weight ratio of 3 to 7 (PAN:gelatin), the best response times were obtained at 0.59 s for elongation and 1.14 s for contraction. Study of the chemical structures of hydrolyzed PAN and gelatin, as well as the surface morphology of the hydrogel fibers, indicated that the mechanism of formation of hydrogel fibers is closely interconnected with their pH-sensitive behavior. From the standpoint of the mechanism we also found that the addition of urea gave rise to hydrogel fibers with a controllable morphology, influenced by the pH-sensitive behavior. CONCLUSION: The hydrogel system reported here is simple in preparation, but quite complex in chemical structure. The strong response of the fibers to pH provides some idea on the development of new artificial muscle systems. Copyright © 2008 Society of Chemical Industry [source]