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Sensors, Volume 7, Issue 10 (October 2007), Pages 2028-2491

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Open AccessArticle A Wetness Index Using Terrain-Corrected Surface Temperature and Normalized Difference Vegetation Index Derived from Standard MODIS Products: An Evaluation of Its Use in a Humid Forest-Dominated Region of Eastern Canada
Sensors 2007, 7(10), 2028-2048; doi:10.3390/s7102028
Received: 6 September 2007 / Accepted: 26 September 2007 / Published: 1 October 2007
Cited by 25 | PDF Full-text (1607 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we develop a method to estimate land-surface water content in amostly forest-dominated (humid) and topographically-varied region of eastern Canada. Theapproach is centered on a temperature-vegetation wetness index (TVWI) that uses standard 8-day MODIS-based image composites of land surface temperature (T
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In this paper we develop a method to estimate land-surface water content in amostly forest-dominated (humid) and topographically-varied region of eastern Canada. Theapproach is centered on a temperature-vegetation wetness index (TVWI) that uses standard 8-day MODIS-based image composites of land surface temperature (TS) and surface reflectanceas primary input. In an attempt to improve estimates of TVWI in high elevation areas, terrain-induced variations in TS are removed by applying grid, digital elevation model-basedcalculations of vertical atmospheric pressure to calculations of surface potential temperature(θS). Here, θS corrects TS to the temperature value to what it would be at mean sea level (i.e.,~101.3 kPa) in a neutral atmosphere. The vegetation component of the TVWI uses 8-daycomposites of surface reflectance in the calculation of normalized difference vegetation index(NDVI) values. TVWI and corresponding wet and dry edges are based on an interpretation ofscatterplots generated by plotting θS as a function of NDVI. A comparison of spatially-averaged field measurements of volumetric soil water content (VSWC) and TVWI for the 2003-2005 period revealed that variation with time to both was similar in magnitudes. Growing season, point mean measurements of VSWC and TVWI were 31.0% and 28.8% for 2003, 28.6% and 29.4% for 2004, and 40.0% and 38.4% for 2005, respectively. An evaluation of the long-term spatial distribution of land-surface wetness generated with the new θS-NDVI function and a process-based model of soil water content showed a strong relationship (i.e., r2 = 95.7%). Full article
(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)
Open AccessArticle Investigation on Clarified Fruit Juice Composition by Using Visible Light Micro-Raman Spectroscopy
Sensors 2007, 7(10), 2049-2061; doi:10.3390/s7102049
Received: 21 September 2007 / Accepted: 1 October 2007 / Published: 3 October 2007
Cited by 12 | PDF Full-text (267 KB) | HTML Full-text | XML Full-text
Abstract
Liquid samples of clarified apple and apricot juices at different productionstages were investigated using visible light micro-Raman spectroscopy in order to assessits potential in monitoring fruit juice production. As is well-known, pectin plays a strategicrole in the production of clarified juice and the
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Liquid samples of clarified apple and apricot juices at different productionstages were investigated using visible light micro-Raman spectroscopy in order to assessits potential in monitoring fruit juice production. As is well-known, pectin plays a strategicrole in the production of clarified juice and the possibility of using Raman for its detectionduring production was therefore evaluated. The data analysis has enabled the clearidentification of pectin. In particular, Raman spectra of apple juice samples from washedand crushed fruits revealed a peak at 845 cm-1 (typical of pectin) which disappears in theRaman spectra of depectinised samples. The fructose content was also revealed by thepresence of four peaks at 823 cm-1, 872 cm-1, 918 cm-1 and 975 cm-1. In the case of apricotjuice, several Raman fingerprints of β-carotene at 1008, 1159 and 1520 cm-1 were alsohighlighted. Present results resulted interesting for the exclusive use of optical methods forthe quantitative determination of the above-mentioned substances in place of thebiochemical assays generally used for this purpose, which are time consuming and requiredifferent chemical reagents for each of them. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Quantitative Boundary Support Characterization for Cantilever MEMS
Sensors 2007, 7(10), 2062-2079; doi:10.3390/s7102062
Received: 6 September 2007 / Accepted: 26 September 2007 / Published: 3 October 2007
Cited by 12 | PDF Full-text (1123 KB) | HTML Full-text | XML Full-text
Abstract
Microfabrication limitations are of concern especially for suspended Micro-Electro-Mechanical-Systems (MEMS) microstructures such as cantilevers. The static anddynamic qualities of such microscale devices are directly related to the invariant and variantproperties of the microsystem. Among the invariant properties, microfabrication limitationscan be quantified only after
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Microfabrication limitations are of concern especially for suspended Micro-Electro-Mechanical-Systems (MEMS) microstructures such as cantilevers. The static anddynamic qualities of such microscale devices are directly related to the invariant and variantproperties of the microsystem. Among the invariant properties, microfabrication limitationscan be quantified only after the fabrication of the device through testing. However, MEMSare batch fabricated in large numbers where individual testing is neither possible nor costeffective. Hence, a suitable test algorithm needs to be developed where the test resultsobtained for a few devices can be applied to the whole fabrication batch, and also to thefoundry process in general. In this regard, this paper proposes a method to test MEMScantilevers under variant electro-thermal influences in order to quantify the effectiveboundary support condition obtained for a foundry process. A non-contact optical sensingapproach is employed for the dynamic testing. The Rayleigh-Ritz energy method usingboundary characteristic orthogonal polynomials is employed for the modeling andtheoretical analysis. Full article
Open AccessArticle Determination of DPPH Radical Oxidation Caused by Methanolic Extracts of Some Microalgal Species by Linear Regression Analysis of Spectrophotometric Measurements
Sensors 2007, 7(10), 2080-2095; doi:10.3390/s7102080
Received: 20 June 2007 / Accepted: 1 October 2007 / Published: 3 October 2007
Cited by 58 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
The demonstrated modified spectrophotometric method makes use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and its specific absorbance properties. Theabsorbance decreases when the radical is reduced by antioxidants. In contrast to otherinvestigations, the absorbance was measured at a wavelength of 550 nm. This wavelengthenabled the
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The demonstrated modified spectrophotometric method makes use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and its specific absorbance properties. Theabsorbance decreases when the radical is reduced by antioxidants. In contrast to otherinvestigations, the absorbance was measured at a wavelength of 550 nm. This wavelengthenabled the measurements of the stable free DPPH radical without interference frommicroalgal pigments. This approach was applied to methanolic microalgae extracts for twodifferent DPPH concentrations. The changes in absorbance measured vs. the concentrationof the methanolic extract resulted in curves with a linear decrease ending in a saturationregion. Linear regression analysis of the linear part of DPPH reduction versus extractconcentration enabled the determination of the microalgae’s methanolic extractsantioxidative potentials which was independent to the employed DPPH concentrations. Theresulting slopes showed significant differences (6 - 34 μmol DPPH g-1 extractconcentration) between the single different species of microalgae (Anabaena sp.,Isochrysis galbana, Phaeodactylum tricornutum, Porphyridium purpureum, Synechocystissp. PCC6803) in their ability to reduce the DPPH radical. The independency of the signal on the DPPH concentration is a valuable advantage over the determination of the EC50 value. Full article
(This article belongs to the Special Issue Physiological Sensing)
Open AccessArticle Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines
Sensors 2007, 7(10), 2096-2114; doi:10.3390/s7102096
Received: 19 September 2007 / Accepted: 27 September 2007 / Published: 3 October 2007
Cited by 33 | PDF Full-text (580 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by theabsorption
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The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II),Ca(II) and Na(I) was also explored. Full article
(This article belongs to the Special Issue Supramolecular Sensors)
Open AccessArticle Modeling Forest Productivity Using Envisat MERIS Data
Sensors 2007, 7(10), 2115-2127; doi:10.3390/S7102115
Received: 4 September 2007 / Accepted: 2 October 2007 / Published: 5 October 2007
Cited by 13 | PDF Full-text (2668 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this study was to derive land cover products with a 300-m pixelresolution of Envisat MERIS (Medium Resolution Imaging Spectrometer) to quantify netprimary productivity (NPP) of conifer forests of Taurus Mountain range along the EasternMediterranean coast of Turkey. The Carnegie-Ames-Stanford approach
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The aim of this study was to derive land cover products with a 300-m pixelresolution of Envisat MERIS (Medium Resolution Imaging Spectrometer) to quantify netprimary productivity (NPP) of conifer forests of Taurus Mountain range along the EasternMediterranean coast of Turkey. The Carnegie-Ames-Stanford approach (CASA) was usedto predict annual and monthly regional NPP as modified by temperature, precipitation,solar radiation, soil texture, fractional tree cover, land cover type, and normalizeddifference vegetation index (NDVI). Fractional tree cover was estimated using continuoustraining data and multi-temporal metrics of 47 Envisat MERIS images of March 2003 toSeptember 2005 and was derived by aggregating tree cover estimates made from high-resolution IKONOS imagery to coarser Landsat ETM imagery. A regression tree algorithmwas used to estimate response variables of fractional tree cover based on the multi-temporal metrics. This study showed that Envisat MERIS data yield a greater spatial detailin the quantification of NPP over a topographically complex terrain at the regional scalethan those used at the global scale such as AVHRR. Full article
Open AccessArticle Improving Estimation Performance in Networked Control Systems Applying the Send-on-delta Transmission Method
Sensors 2007, 7(10), 2128-2138; doi:10.3390/S7102128
Received: 4 September 2007 / Accepted: 2 October 2007 / Published: 5 October 2007
Cited by 22 | PDF Full-text (247 KB) | HTML Full-text | XML Full-text
Abstract
This paper is concerned with improving performance of a state estimationproblem over a network in which a send-on-delta (SOD) transmission method is used. TheSOD method requires that a sensor node transmit data to the estimator node only if itsmeasurement value changes more than
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This paper is concerned with improving performance of a state estimationproblem over a network in which a send-on-delta (SOD) transmission method is used. TheSOD method requires that a sensor node transmit data to the estimator node only if itsmeasurement value changes more than a given specified δ value. This method has beenexplored and applied by researchers because of its efficiency in the network bandwidthimprovement. However, when this method is used, it is not ensured that the estimator nodereceives data from the sensor nodes regularly at every estimation period. Therefore, wepropose a method to reduce estimation error in case of no sensor data reception. When theestimator node does not receive data from the sensor node, the sensor value is known to bein a (−δi , δi ) interval from the last transmitted sensor value. This implicit information hasbeen used to improve estimation performance in previous studies. The main contribution ofthis paper is to propose an algorithm, where the sensor value interval is reduced to(−δi / 2, δi / 2) in certain situations. Thus, the proposed algorithm improves the overallestimation performance without any changes in the send-on-delta algorithms of the sensornodes. Through numerical simulations, we demonstrate the feasibility and the usefulness ofthe proposed method. Full article
(This article belongs to the Special Issue Intelligent Sensors)
Open AccessArticle Physical-Mechanical Properties of Nitrodopes Affected by Ultra-Violet Radiation
Sensors 2007, 7(10), 2139-2156; doi:10.3390/S7102139
Received: 11 June 2007 / Accepted: 3 October 2007 / Published: 9 October 2007
Cited by 4 | PDF Full-text (298 KB) | HTML Full-text | XML Full-text
Abstract
The FTIR spectroscopy has been employed in this research work to monitor theprocess of nitrodope photodegradation, by measuring surfaces of bands typical of a nitrogroup. Nitric esters are subject to degradation, which is reflected on a quantitative ratio ofthe surfaces of the IR
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The FTIR spectroscopy has been employed in this research work to monitor theprocess of nitrodope photodegradation, by measuring surfaces of bands typical of a nitrogroup. Nitric esters are subject to degradation, which is reflected on a quantitative ratio ofthe surfaces of the IR bands that originate from the nitric ester. The obtained results showthat the length of the UV rays’ activity on the samples over the time periods of 240, 480and 960 minutes directly affects the spectrum appearance of the same sample before andafter the irradiation. The longer the action time of the UV rays and the higher a masspercentage of nitrocellulose in the nitrodope is, the smaller the bands’ surfaces become, i.e.the level of degradation is higher. In order to confirm the degradation of nitrodope, thedegree of crosslinking has also been examined by determining the König hardness and alsothe mean viscosity molar mass has been defined repeatedly applying the capillaryviscosimetry method. Full article
Open AccessArticle Wireless Sensor/Actuator Network Design for Mobile Control Applications
Sensors 2007, 7(10), 2157-2173; doi:10.3390/s7102157
Received: 3 October 2007 / Accepted: 8 October 2007 / Published: 9 October 2007
Cited by 76 | PDF Full-text (486 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor/actuator networks (WSANs) are emerging as a new generationof sensor networks. Serving as the backbone of control applications, WSANs will enablean unprecedented degree of distributed and mobile control. However, the unreliability ofwireless communications and the real-time requirements of control applications raise greatchallenges
[...] Read more.
Wireless sensor/actuator networks (WSANs) are emerging as a new generationof sensor networks. Serving as the backbone of control applications, WSANs will enablean unprecedented degree of distributed and mobile control. However, the unreliability ofwireless communications and the real-time requirements of control applications raise greatchallenges for WSAN design. With emphasis on the reliability issue, this paper presents anapplication-level design methodology for WSANs in mobile control applications. Thesolution is generic in that it is independent of the underlying platforms, environment,control system models, and controller design. To capture the link quality characteristics interms of packet loss rate, experiments are conducted on a real WSAN system. From theexperimental observations, a simple yet efficient method is proposed to deal withunpredictable packet loss on actuator nodes. Trace-based simulations give promisingresults, which demonstrate the effectiveness of the proposed approach. Full article
Open AccessArticle Magnetostrictive Micro Mirrors for an Optical Switch Matrix
Sensors 2007, 7(10), 2174-2182; doi:10.3390/s7102174
Received: 18 July 2007 / Accepted: 27 September 2007 / Published: 9 October 2007
Cited by 6 | PDF Full-text (394 KB) | HTML Full-text | XML Full-text
Abstract
We have developed a wireless-controlled compact optical switch by siliconmicromachining techniques with DC magnetron sputtering. For the optical switchingoperation, micro mirror is designed as cantilever shape size of 5mm×800μm×50μm.TbDyFe film is sputter-deposited on the upper side of the mirror with the condition as:
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We have developed a wireless-controlled compact optical switch by siliconmicromachining techniques with DC magnetron sputtering. For the optical switchingoperation, micro mirror is designed as cantilever shape size of 5mm×800μm×50μm.TbDyFe film is sputter-deposited on the upper side of the mirror with the condition as: Argas pressure below 1.2×10-9 torr, DC input power of 180W and heating temperature of up to250°C for the wireless control of each component. Mirrors are actuated by externallyapplied magnetic fields for the micro application. Applied beam path can be changedaccording to the direction and the magnitude of applied magnetic field. Reflectivity changes,M-H curves and X-ray diffractions of sputtered mirrors are measured to determine magneto-optical, magneto-elastic properties with variation in sputtered film thickness. The deflectedangle-magnetic field characteristics of the fabricated mirror are measured. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
Open AccessArticle High-rise Buildings versus Outdoor Thermal Environment in Chongqing
Sensors 2007, 7(10), 2183-2200; doi:10.3390/s7102183
Received: 30 July 2007 / Accepted: 27 September 2007 / Published: 11 October 2007
PDF Full-text (1213 KB) | HTML Full-text | XML Full-text
Abstract
This paper gives a brief description of the over quick urbanization sinceChongqing, one of the biggest cities in China, has been a municipality directly under theCentral Government in 1997, excessive development and exceeding increase of high-risebuildings because of its special geographical position which
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This paper gives a brief description of the over quick urbanization sinceChongqing, one of the biggest cities in China, has been a municipality directly under theCentral Government in 1997, excessive development and exceeding increase of high-risebuildings because of its special geographical position which finally leads to the worseningof the urban outdoor thermal environment. Then, this paper makes a bright balance to thefield measurement and simulated results of the wind speed field, temperature field of onemultifunctional high-rise building in Chongqing university located in the city center, andthe contrasted results validate the correctness of CFD in the outdoor thermal environmentalsimulation, expose the disadvantages of high-rise buildings on the aspects of blocking thewind field, decreasing wind speed which results in accumulation of the air-conditioningheat revolving around and periscian region where sunshine can not rip into. Finally, inorder to improve the urban outdoor thermal environment near the high-rise buildingsespecially for the angle of natural ventilation, this paper simulates the wind environment indifferent architectural compositions and architectural layouts by CFD, and the simulatedresults show that freestyle and tower buildings which can guarantee the wind speed andtake the air-conditioning heat away are much suitable and reasonable for the specialChongqing geography. These conclusions can also be used as a reference in othermountain cities, especially for the one with a great number of populations. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessArticle Multi-agent Negotiation Mechanisms for Statistical Target Classification in Wireless Multimedia Sensor Networks
Sensors 2007, 7(10), 2201-2237; doi:10.3390/s7102201
Received: 24 September 2007 / Accepted: 9 October 2007 / Published: 11 October 2007
Cited by 2 | PDF Full-text (474 KB) | HTML Full-text | XML Full-text
Abstract
The recent availability of low cost and miniaturized hardware has allowedwireless sensor networks (WSNs) to retrieve audio and video data in real worldapplications, which has fostered the development of wireless multimedia sensor networks(WMSNs). Resource constraints and challenging multimedia data volume makedevelopment of efficient
[...] Read more.
The recent availability of low cost and miniaturized hardware has allowedwireless sensor networks (WSNs) to retrieve audio and video data in real worldapplications, which has fostered the development of wireless multimedia sensor networks(WMSNs). Resource constraints and challenging multimedia data volume makedevelopment of efficient algorithms to perform in-network processing of multimediacontents imperative. This paper proposes solving problems in the domain of WMSNs fromthe perspective of multi-agent systems. The multi-agent framework enables flexible networkconfiguration and efficient collaborative in-network processing. The focus is placed ontarget classification in WMSNs where audio information is retrieved by microphones. Todeal with the uncertainties related to audio information retrieval, the statistical approachesof power spectral density estimates, principal component analysis and Gaussian processclassification are employed. A multi-agent negotiation mechanism is specially developed toefficiently utilize limited resources and simultaneously enhance classification accuracy andreliability. The negotiation is composed of two phases, where an auction based approach isfirst exploited to allocate the classification task among the agents and then individual agentdecisions are combined by the committee decision mechanism. Simulation experiments withreal world data are conducted and the results show that the proposed statistical approachesand negotiation mechanism not only reduce memory and computation requi Full article
Open AccessArticle An Optical Biosensor based on Immobilization of Laccase and MBTH in Stacked Films for the Detection of Catechol.
Sensors 2007, 7(10), 2238-2250; doi:10.3390/s7102238
Received: 14 March 2007 / Accepted: 6 June 2007 / Published: 11 October 2007
Cited by 29 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
The fabrication of an optical biosensor by using stacked films where 3-methyl-2-benzothiazolinone hydrazone (MBTH) was immobilized in a hybrid nafion/sol-gelsilicate film and laccase in a chitosan film for the detection of phenolic compounds wasdescribed. Quinone and/or phenoxy radical product from the enzymatic oxidation
[...] Read more.
The fabrication of an optical biosensor by using stacked films where 3-methyl-2-benzothiazolinone hydrazone (MBTH) was immobilized in a hybrid nafion/sol-gelsilicate film and laccase in a chitosan film for the detection of phenolic compounds wasdescribed. Quinone and/or phenoxy radical product from the enzymatic oxidation ofphenolic compounds was allowed to couple with MBTH to form a colored azo-dye productfor spectrophometric detection. The biosensor demonstrated a linear response to catecholconcentration range of 0.5-8.0 mM with detection limit of 0.33 mM and response time of10 min. The reproducibility of the fabricated biosensor was good with RSD value of 5.3 %(n = 8) and stable for at least 2 months. The use of the hybrid materials of nafion/sol-gelsilicate to immobilize laccase has altered the selectivity of the enzyme to various phenoliccompounds such as catechol, guaicol, o-cresol and m-cresol when compared to the non-immobilized enzyme. When immobilized in this hybrid film, the biosensor response onlyto catechol and not other phenolic compounds investigated. Immobilization in this hybridmaterial has enable the biosensor to be more selective to catechol compared with the non-immobilized enzyme. This shows that by a careful selection of different immobilizationmatrices, the selectivity of an enzyme can be modified to yield a biosensor with goodselectivity towards certain targeted analytes. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle A Urea Biosensor from Stacked Sol-Gel Films with Immobilized Nile Blue Chromoionophore and Urease Enzyme
Sensors 2007, 7(10), 2251-2262; doi:10.3390/s7102251
Received: 3 August 2007 / Accepted: 13 September 2007 / Published: 11 October 2007
Cited by 20 | PDF Full-text (226 KB) | HTML Full-text | XML Full-text
Abstract
An optical urea biosensor was fabricated by stacking several layers of sol-gelfilms. The stacking of the sol-gel films allowed the immobilization of a Nile Bluechromoionophore (ETH 5294) and urease enzyme separately without the need of anychemical attachment procedure. The absorbance response of the
[...] Read more.
An optical urea biosensor was fabricated by stacking several layers of sol-gelfilms. The stacking of the sol-gel films allowed the immobilization of a Nile Bluechromoionophore (ETH 5294) and urease enzyme separately without the need of anychemical attachment procedure. The absorbance response of the biosensor was monitoredat 550 nm, i.e. the deprotonation of the chromoionophore. This multi-layer sol-gel filmformat enabled higher enzyme loading in the biosensor to be achieved. The urea opticalbiosensor constructed from three layers of sol-gel films that contained urease demonstrateda much wider linear response range of up to 100 mM urea when compared with biosensorsthat constructed from 1-2 layers of films. Analysis of urea in urine samples with thisoptical urea biosensor yielded results similar to that determined by a spectrophotometricmethod using the reagent p-dimethylaminobenzaldehyde (R2 = 0.982, n = 6). The averagerecovery of urea from urine samples using this urea biosensor is approximately 103%. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Enhancement of BSA Binding on Au Surfaces by calix[4]bisazacrown Monolayer
Sensors 2007, 7(10), 2263-2272; doi:10.3390/s7102263
Received: 21 September 2007 / Accepted: 10 October 2007 / Published: 11 October 2007
Cited by 17 | PDF Full-text (612 KB) | HTML Full-text | XML Full-text
Abstract
Effective investigation of biomolecular structure and function with chip-basedmodern instruments often requires reliable and steady attachment of designatedbiomolecules on substrate. Here, we investigated the formation of self-assembled monolayer(SAM) with a new calix[4]arene derivative containing bisazacrown ether at the lower rim(calix[4]bisazacrown) where ammonium moieties
[...] Read more.
Effective investigation of biomolecular structure and function with chip-basedmodern instruments often requires reliable and steady attachment of designatedbiomolecules on substrate. Here, we investigated the formation of self-assembled monolayer(SAM) with a new calix[4]arene derivative containing bisazacrown ether at the lower rim(calix[4]bisazacrown) where ammonium moieties of proteins can mainly be interacted with.Immobilization process of protein using bovine serum albumin (BSA) on the Au surfacemodified with calix[4]bisazacrown monolyer as an artificial linker system was monitored bysurface plasmon resonance (SPR) technique. The surface concentration of BSA calculatedby the simulation of SPR experimental data was higher than that of a well-known similarcommercial protein linker. These results can help in modeling and understanding of proteinimmobilization on solid surface as well as further development lab-on-a-chip (LOC) devicesfor biomedical diagnosis kit of certain protein related diseases as biomarkers. Full article
Open AccessArticle Modeling Potential Distribution and Carbon Dynamics of Natural Terrestrial Ecosystems: A Case Study of Turkey
Sensors 2007, 7(10), 2273-2296; doi:10.3390/s7102273
Received: 4 October 2007 / Accepted: 11 October 2007 / Published: 11 October 2007
Cited by 12 | PDF Full-text (2996 KB) | HTML Full-text | XML Full-text
Abstract
We derived a simple model that relates the classification of biogeoclimatezones, (co)existence and fractional coverage of plant functional types (PFTs), and patternsof ecosystem carbon (C) stocks to long-term average values of biogeoclimatic indices in atime- and space-varying fashion from climate–vegetation equilibrium models. ProposedDynamic
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We derived a simple model that relates the classification of biogeoclimatezones, (co)existence and fractional coverage of plant functional types (PFTs), and patternsof ecosystem carbon (C) stocks to long-term average values of biogeoclimatic indices in atime- and space-varying fashion from climate–vegetation equilibrium models. ProposedDynamic Ecosystem Classification and Productivity (DECP) model is based on the spatialinterpolation of annual biogeoclimatic variables through multiple linear regression (MLR)models and inverse distance weighting (IDW) and was applied to the entire Turkey of780,595 km2 on a 500 m x 500 m grid resolution. Estimated total net primary production(TNPP) values of mutually exclusive PFTs ranged from 108 26 to 891 207 Tg C yr-1under the optimal conditions and from 16 7 to 58 23 Tg C yr-1 under the growth-limiting conditions for all the natural ecosystems in Turkey. Total NPP values ofcoexisting PFTs ranged from 178 36 to 1231 253 Tg C yr-1 under the optimalconditions and from 23 8 to 92 31 Tg C yr-1 under the growth-limiting conditions. Thenational steady state soil organic carbon (SOC) storage in the surface one meter of soil wasestimated to range from 7.5 1.8 to 36.7 7.8 Pg C yr-1 under the optimal conditions andfrom 1.3 0.7 to 5.8 2.6 Pg C yr-1 under the limiting conditions, with the national range of 1.3 to 36.7 Pg C elucidating 0.1% and 2.8% of the global SOC value (1272.4 Pg C), respectively. Our comparisons with literature compilations indicate that estimated patterns of biogeoclimate zones, PFTs, TNPP and SOC storage by the DECP model agree reasonably well with measurements from field and remotely sensed data. Full article
Open AccessArticle Impact of Climate Change on Irrigation Demand and Crop Growth in a Mediterranean Environment of Turkey
Sensors 2007, 7(10), 2297-2315; doi:10.3390/s7102297
Received: 25 September 2007 / Accepted: 15 October 2007 / Published: 16 October 2007
Cited by 32 | PDF Full-text (334 KB) | HTML Full-text | XML Full-text
Abstract
A simulation study was carried out to describe effects of climate change on cropgrowth and irrigation water demand for a wheat-maize cropping sequence in aMediterranean environment of Turkey. Climate change scenarios were projected using dataof the three general circulation models—GCMs (CGCM2, ECHAM4 and
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A simulation study was carried out to describe effects of climate change on cropgrowth and irrigation water demand for a wheat-maize cropping sequence in aMediterranean environment of Turkey. Climate change scenarios were projected using dataof the three general circulation models—GCMs (CGCM2, ECHAM4 and MRI)—for theperiod of 1990 to 2100 and one regional climate model—RCM—for the period of 2070 to2079. Potential impacts of climate change based on GCMs data were estimated for the A2scenario in the Special Report on Emission Scenarios (SRES). The forcing data for theboundary condition of the RCM were given by the MRI model. Daily CGCM2 and RCMdata were used for computations of water balance and crop development. Predictionsderived from the models about changes in irrigation and crop growth in this study coveredthe period of 2070 to 2079 relative to the baseline period of 1994 to 2003. The effects ofclimate change on water demand and on wheat and maize yields were predicted using thedetailed crop growth subroutine of the SWAP (Soil-Water-Atmosphere-Plant) model. Precipitation was projected to decrease by about 163, 163 and 105 mm during the periodof 1990 to 2100 under the A2 scenario of the CGCM2, ECHAM4 and MRI models,respectively. The CGCM2, ECHAM4 and MRI models projected a temperature rise of 4.3,5.3 and 3.1 oC, respectively by 2100. An increase in temperature may result in a higherevaporative demand of the atmosphere. However, actual evapotranspiration (ETa) fromwheat cropland under a doubling CO2 concentration for the period of 2070 to 2079 wasSensors 2007, 7 2298 predicted to decrease by about 28 and 8% relative to the baseline period based on the CGCM2 and RCM data, respectively. According to these models, irrigation demand by wheat would be higher for the same period due to a decrease in precipitation. Both ETa and irrigation water for maize cropland were projected to decrease by 24 and 15% according to the CGCM2, and 28 and 22% according to the RCM, respectively. The temperature rise accelerated crop development but shortened the growing period by 24 days for wheat and 9 days for maize according to the CGCM2 data. The shortened growth duration with a higher temperature reduced the biomass accumulation of both crops regardless of CO2-fertilization effect. With the combined effect of CO2-fertilization and increased temperature, the CGCM2 and RCM projections resulted in an increase by 16 and 36% in grain yield of wheat and a decrease by about 25% and an increase by 3% in maize yield, respectively. Full article
Open AccessArticle Effect of Estimated Daily Global Solar Radiation Data on the Results of Crop Growth Models
Sensors 2007, 7(10), 2330-2362; doi:10.3390/s7102330
Received: 14 September 2007 / Accepted: 15 October 2007 / Published: 16 October 2007
Cited by 14 | PDF Full-text (3810 KB) | HTML Full-text | XML Full-text
Abstract
The results of previous studies have suggested that estimated daily globalradiation (RG) values contain an error that could compromise the precision of subsequentcrop model applications. The following study presents a detailed site and spatial analysis ofthe RG error propagation in
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The results of previous studies have suggested that estimated daily globalradiation (RG) values contain an error that could compromise the precision of subsequentcrop model applications. The following study presents a detailed site and spatial analysis ofthe RG error propagation in CERES and WOFOST crop growth models in Central Europeanclimate conditions. The research was conducted i) at the eight individual sites in Austria andthe Czech Republic where measured daily RG values were available as a reference, withseven methods for RG estimation being tested, and ii) for the agricultural areas of the CzechRepublic using daily data from 52 weather stations, with five RG estimation methods. In thelatter case the RG values estimated from the hours of sunshine using the ångström-Prescottformula were used as the standard method because of the lack of measured RG data. At thesite level we found that even the use of methods based on hours of sunshine, which showedthe lowest bias in RG estimates, led to a significant distortion of the key crop model outputs.When the ångström-Prescott method was used to estimate RG, for example, deviationsgreater than ±10 per cent in winter wheat and spring barley yields were noted in 5 to 6 percent of cases. The precision of the yield estimates and other crop model outputs was lowerwhen RG estimates based on the diurnal temperature range and cloud cover were used (mean bias error 2.0 to 4.1 per cent). The methods for estimating RG from the diurnal temperature range produced a wheat yield bias of more than 25 per cent in 12 to 16 per cent of the seasons. Such uncertainty in the crop model outputs makes the reliability of any seasonal yield forecasts or climate change impact assessments questionable if they are based on this type of data. The spatial assessment of the RG data uncertainty propagation over the winter wheat yields also revealed significant differences within the study area. We found that RG estimates based on diurnal temperature range or its combination with daily total precipitation produced a bias of to 30 per cent in the mean winter wheat grain yields in some regions compared with simulations in which RG values had been estimated using the ångström-Prescott formula. In contrast to the results at the individual sites, the methods based on the diurnal temperature range in combination with daily precipitation totals showed significantly poorer performance than the methods based on the diurnal temperature range only. This was due to the marked increase in the bias in RG estimates with altitude, longitude or latitude of given region. These findings in our view should act as an incentive for further research to develop more precise and generally applicable methods for estimating daily RG based more on the underlying physical principles and/or the remote sensing approach. Full article
Open AccessArticle An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery
Sensors 2007, 7(10), 2363-2377; doi:10.3390/s7102363
Received: 30 August 2007 / Accepted: 16 October 2007 / Published: 17 October 2007
Cited by 3 | PDF Full-text (965 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present an inexpensive electronic measurement instrumentationdeveloped in our laboratory, to measure and plot the impedance of a loaded fuel cell orbattery. Impedance measurements were taken by using the load modulation method. Thisinstrumentation has been developed around a VXI system
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In this paper we present an inexpensive electronic measurement instrumentationdeveloped in our laboratory, to measure and plot the impedance of a loaded fuel cell orbattery. Impedance measurements were taken by using the load modulation method. Thisinstrumentation has been developed around a VXI system stand which controls electroniccards. Software under Hpvee® was developed for automatic measurements and the layout ofthe impedance of the fuel cell on load. The measurement environment, like the ambienttemperature, the fuel cell temperature, the level of the hydrogen, etc..., were taken withseveral sensors that enable us to control the measurement. To filter the noise and theinfluence of the 50Hz, we have implemented a synchronous detection which filters in a verynarrow way around the useful signal. The theoretical result obtained by a simulation underPspice® of the method used consolidates the choice of this method and the possibility ofobtaining correct and exploitable results. The experimental results are preliminary results ona 12V vehicle battery, having an inrush current of 330A and a capacity of 40Ah (impedancemeasurements on a fuel cell are in progress, and will be the subject of a forthcoming paper).The results were plotted at various nominal voltages of the battery (12.7V, 10V, 8V and 5V)and with two imposed currents (0.6A and 4A). The Nyquist diagram resulting from theexperimental data enable us to show an influence of the load of the battery on its internalimpedance. The similitude in the graph form and in order of magnitude of the valuesobtained (both theoretical and practical) enables us to validate our electronic measurementinstrumentation. One of the future uses for this instrumentation is to integrate it with several control sensors, on a vehicle as an embedded system to monitor the degradation of fuel cell membranes. Full article
Open AccessArticle Development of QCM Trimethylamine Sensor Based on Water Soluble Polyaniline
Sensors 2007, 7(10), 2378-2388; doi:10.3390/s7102378
Received: 30 August 2007 / Accepted: 16 October 2007 / Published: 17 October 2007
Cited by 16 | PDF Full-text (781 KB) | HTML Full-text | XML Full-text
Abstract
A rapid, sensitive, low-cost device to detect trimethylamine was presented in thispaper. The preparation of water soluble polyaniline was firstly studied. Then the polyanilinewas characterized via Fourier transform infrared spectroscopy (FTIR), UV-visiblespectroscopy and scanning electron microscopy (SEM). Based on the water solublepolyaniline film,
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A rapid, sensitive, low-cost device to detect trimethylamine was presented in thispaper. The preparation of water soluble polyaniline was firstly studied. Then the polyanilinewas characterized via Fourier transform infrared spectroscopy (FTIR), UV-visiblespectroscopy and scanning electron microscopy (SEM). Based on the water solublepolyaniline film, a quartz crystal microbalance (QCM) sensor for trimethylamine detectionwas fabricated and its characteristics were examined. The sensor consisted of one quartzcrystal oscillator coated with the polyaniline film for sensing and the other one forreference. Pretreated with trimethylamine, the QCM sensor had an excellent linearsensitivity to trimethylamine. Easily recovered by N2 purgation, the response of the sensorexhibited a good repeatability. Responses of the sensor to trimethylamine, ethanol and ethylacetate were compared, and the results showed that the response was related to the polarityof the analyte vapor. Experimental result also showed that the sensitivity of the sensor wasrelatively stable within one month. The simple and feasible method to prepare and coat thepolyaniline sensing film makes it promising for mass production. Full article
Open AccessArticle A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure
Sensors 2007, 7(10), 2389-2401; doi:10.3390/s7102389
Received: 27 August 2007 / Accepted: 10 October 2007 / Published: 17 October 2007
Cited by 71 | PDF Full-text (2229 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a micro-scale air flow sensor based on a free-standingcantilever structure. In the fabrication process, MEMS techniques are used to deposit asilicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitridelayer to form a piezoresistor,
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This paper presents a micro-scale air flow sensor based on a free-standingcantilever structure. In the fabrication process, MEMS techniques are used to deposit asilicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitridelayer to form a piezoresistor, and the resulting structure is then etched to create afreestanding micro-cantilever. When an air flow passes over the surface of the cantileverbeam, the beam deflects in the downward direction, resulting in a small variation in theresistance of the piezoelectric layer. The air flow velocity is determined by measuring thechange in resistance using an external LCR meter. The experimental results indicate that theflow sensor has a high sensitivity (0.0284 ω/ms-1), a high velocity measurement limit (45ms-1) and a rapid response time (0.53 s). Full article
Open AccessArticle Utilizing of Square Wave Voltammetry to Detect Flavonoids in the Presence of Human Urine
Sensors 2007, 7(10), 2402-2418; doi:10.3390/s7102402
Received: 10 September 2007 / Accepted: 17 October 2007 / Published: 19 October 2007
Cited by 41 | PDF Full-text (573 KB) | HTML Full-text | XML Full-text
Abstract
About biological affecting of flavonoids on animal organisms is known less,thus we selected flavonoids, flavanones and flavones, and their glycosides, which wereexamined as potential inducers of cytochrome(s) P450 when administrated by gavages intoexperimental male rats. The study was focused on induction of CYP1A1,
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About biological affecting of flavonoids on animal organisms is known less,thus we selected flavonoids, flavanones and flavones, and their glycosides, which wereexamined as potential inducers of cytochrome(s) P450 when administrated by gavages intoexperimental male rats. The study was focused on induction of CYP1A1, the majorcytochrome P450 involved in carcinogen activation. The data obtained demonstrate thenecessity of taking into account not only ability of flavonoids to bind to Ah receptor(induction factor) but also to concentrate on their distribution and metabolism (includingcolon microflora) in the body. After that we examined certain flavonoids as potential inducers of cytochrome P450, we wanted to suggest and optimize suitable electrochemical technique for determination of selected flavonoids (quercetin, quercitrin, rutin, chrysin and diosmin) in body liquids. For these purposes, we selected square wave voltannetry using carbon paste electrode. Primarily we aimed on investigation of their basic electrochemical behaviour. After that we have optimized frequency, step potential and supporting electrolyte. Based on the results obtained, we selected the most suitable conditions for determination of the flavonoids as follows: frequency 180 Hz, step potential 1.95 mV/s and phosphate buffer of pH 7 as supporting electrolyte. Detection limits (3 S/N) of the flavonoids were from units to tens of nM except diosmin, where the limit were higher than μM. In addition, we attempted to suggest a sensor for analysis of flavonoids in urine. It clearly follows from the results obtained that flavonoids can be analysed in the presence of animal urine, because urine did not influence much the signals of flavonoids (recoveries of the signals were about 90 %). Full article
Open AccessArticle Shapes of Differential Pulse Voltammograms and Level of Metallothionein at Different Animal Species
Sensors 2007, 7(10), 2419-2429; doi:10.3390/s7102419
Received: 1 October 2007 / Accepted: 17 October 2007 / Published: 19 October 2007
Cited by 21 | PDF Full-text (235 KB) | HTML Full-text | XML Full-text
Abstract
Metallothioneins play a key role in maintaining homeostasis of essential metalsand in protecting of cells against metal toxicity as well as oxidative damaging. Exceptinghumans, blood levels of metallothionein have not yet been reported from any animalspecies. Blood plasma samples of 9 animal species
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Metallothioneins play a key role in maintaining homeostasis of essential metalsand in protecting of cells against metal toxicity as well as oxidative damaging. Exceptinghumans, blood levels of metallothionein have not yet been reported from any animalspecies. Blood plasma samples of 9 animal species were analysed by the adsorptive transferstripping technique to obtain species specific voltammograms. Quite distinct records wereobtained from the Takin (Budorcas taxicolor), while other interesting records were observedin samples from the European Bison (Bison bonasus bonasus) and the Red-eared Slider(Trachemys scripta elegans). To quantify metallothionein the catalytic peak Cat2 was used,well developed in the Domestic Fowl (Gallus gallus f. domestica) and showing a very lowsignal in the Red Deer (Cervus elaphus). The highest levels of metallothionein reachingover 20 μM were found in the Domestic Fowl. High levels of MT were also found in theBearded Dragon (Pogona vitticeps) and the Grey Wolf (Canis lupus lupus). The lowestvalues of about 1-3 μM were determined in the Red-eared Slider, Takin and Red Deer. Employing a simple electrochemical detection it was possible to examine variation in blood metallothionein in different species of vertebrates. Full article
Open AccessArticle Planar Array Sensor for High-speed Component Distribution Imaging in Fluid Flow Applications
Sensors 2007, 7(10), 2430-2445; doi:10.3390/s7102430
Received: 30 August 2007 / Accepted: 17 October 2007 / Published: 19 October 2007
Cited by 16 | PDF Full-text (1183 KB) | HTML Full-text | XML Full-text
Abstract
A novel planar array sensor based on electrical conductivity measurements ispresented which may be applied to visualize surface fluid distributions. The sensor ismanufactured using printed-circuit board fabrication technology and comprises of 64 x 64interdigital sensing structures. An associated electronics measures the electricalconductivity of
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A novel planar array sensor based on electrical conductivity measurements ispresented which may be applied to visualize surface fluid distributions. The sensor ismanufactured using printed-circuit board fabrication technology and comprises of 64 x 64interdigital sensing structures. An associated electronics measures the electricalconductivity of the fluid over each individual sensing structure in a multiplexed manner byapplying a bipolar excitation voltage and by measuring the electrical current flowing from adriver electrode to a sensing electrode. After interrogating all sensing structures, a two-dimensional image of the conductivity distribution over a surface is obtained which in turnrepresents fluid distributions over sensor’s surface. The employed electronics can acquire upto 2500 frames per second thus being able to monitor fast transient phenomena. The systemhas been evaluated regarding measurement accuracy and depth sensitivity. Furthermore, theapplication of the sensor in the investigation of two different flow applications is presented. Full article
(This article belongs to the Special Issue Intelligent Sensors)
Open AccessArticle Electrochemical Sensor for Tryptophan Determination Based on Copper-cobalt Hexacyanoferrate Film Modified Graphite Electrode
Sensors 2007, 7(10), 2446-2457; doi:10.3390/s7102446
Received: 3 July 2007 / Accepted: 15 October 2007 / Published: 19 October 2007
Cited by 31 | PDF Full-text (340 KB) | HTML Full-text | XML Full-text
Abstract
In this work, the development of a tryptophan sensor and its application to milkare described. The mixed metal (copper and cobalt) hexacynoferrates are electrodepositedon the graphite electrode, and this film exhibits an electrocatalytic activity towards for theoxidation of tryptophan. The experimental conditions, including
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In this work, the development of a tryptophan sensor and its application to milkare described. The mixed metal (copper and cobalt) hexacynoferrates are electrodepositedon the graphite electrode, and this film exhibits an electrocatalytic activity towards for theoxidation of tryptophan. The experimental conditions, including the scan cycles, the ratio ofcopper(II) and cobalt(II), pH value, applied potential, are investigated in detail. At theoptimal conditions, the eletctrocatalytic response is a linear relationship with theconcentration of tryptophan in the range of 10 μM and 900 μM, with a detection limit ofabout 6 μM. This modified electrode was also successfully used to detect the tryptophanconcentration in milk. Full article
Open AccessArticle Operational Mapping of Soil Moisture Using Synthetic Aperture Radar Data: Application to the Touch Basin (France)
Sensors 2007, 7(10), 2458-2483; doi:10.3390/s7102458
Received: 31 August 2007 / Accepted: 21 October 2007 / Published: 22 October 2007
Cited by 34 | PDF Full-text (801 KB) | HTML Full-text | XML Full-text
Abstract
Soil moisture is a key parameter in different environmental applications, suchas hydrology and natural risk assessment. In this paper, surface soil moisture mappingwas carried out over a basin in France using satellite synthetic aperture radar (SAR)images acquired in 2006 and 2007 by C-band
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Soil moisture is a key parameter in different environmental applications, suchas hydrology and natural risk assessment. In this paper, surface soil moisture mappingwas carried out over a basin in France using satellite synthetic aperture radar (SAR)images acquired in 2006 and 2007 by C-band (5.3 GHz) sensors. The comparisonbetween soil moisture estimated from SAR data and in situ measurements shows goodagreement, with a mapping accuracy better than 3%. This result shows that themonitoring of soil moisture from SAR images is possible in operational phase. Moreover,moistures simulated by the operational Météo-France ISBA soil-vegetation-atmospheretransfer model in the SIM-Safran-ISBA-Modcou chain were compared to radar moistureestimates to validate its pertinence. The difference between ISBA simulations and radarestimates fluctuates between 0.4 and 10% (RMSE). The comparison between ISBA andgravimetric measurements of the 12 March 2007 shows a RMSE of about 6%. Generally,these results are very encouraging. Results show also that the soil moisture estimatedfrom SAR images is not correlated with the textural units defined in the European Soil Geographical Database (SGDBE) at 1:1000000 scale. However, dependence was observed between texture maps and ISBA moisture. This dependence is induced by the use of the texture map as an input parameter in the ISBA model. Even if this parameter is very important for soil moisture estimations, radar results shown that the textural map scale at 1:1000000 is not appropriate to differentiate moistures zones. Full article
(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)
Open AccessArticle D-galactose/D-glucose-binding Protein from Escherichia coli as Probe for a Non-consuming Glucose Implantable Fluorescence Biosensor
Sensors 2007, 7(10), 2484-2491; doi:10.3390/s7102484
Received: 3 October 2007 / Accepted: 21 October 2007 / Published: 24 October 2007
Cited by 5 | PDF Full-text (304 KB) | HTML Full-text | XML Full-text
Abstract
D-Galactose/D-glucose-binding protein from E. coli (GGBP) is a monomer thatbinds glucose with high affinity. The protein structure of GGBP is organized in twoprincipal domains linked by a hinge region that form the sugar-binding site. In this workwe show that the mutant form of
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D-Galactose/D-glucose-binding protein from E. coli (GGBP) is a monomer thatbinds glucose with high affinity. The protein structure of GGBP is organized in twoprincipal domains linked by a hinge region that form the sugar-binding site. In this workwe show that the mutant form of GGBP at the amino acid position 182 can be utilized as aprobe for the development of a non-consuming analyte fluorescence biosensor to monitorthe glucose level in diabetes health care. Full article
(This article belongs to the Special Issue Optical Biosensors)

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Open AccessReview Non-invasive Optical Biosensor for Probing Cell Signaling
Sensors 2007, 7(10), 2316-2329; doi:10.3390/s7102316
Received: 24 September 2007 / Accepted: 15 October 2007 / Published: 16 October 2007
Cited by 46 | PDF Full-text (396 KB) | HTML Full-text | XML Full-text
Abstract
Cell signaling mediated through a cellular target is encoded by spatial andtemporal dynamics of downstream signaling networks. The coupling of temporal dynamicswith spatial gradients of signaling activities guides cellular responses upon stimulation.Monitoring the integration of cell signaling in real time, if realized, would
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Cell signaling mediated through a cellular target is encoded by spatial andtemporal dynamics of downstream signaling networks. The coupling of temporal dynamicswith spatial gradients of signaling activities guides cellular responses upon stimulation.Monitoring the integration of cell signaling in real time, if realized, would provide a newdimension for understanding cell biology and physiology. Optical biosensors includingresonant waveguide grating (RWG) biosensor manifest a physiologically relevant andintegrated cellular response related to dynamic redistribution of cellular matters, thusproviding a non-invasive means for cell signaling study. This paper reviews recentprogresses in biosensor instrumentation, and theoretical considerations and potentialapplications of optical biosensors for whole cell sensing. Full article
(This article belongs to the Special Issue Optical Biosensors)

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