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Sensors, Volume 8, Issue 7 (July 2008), Pages 4033-4486

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Open AccessArticle Laurate Biosensors Image Brain Neurotransmitters In Vivo: Can an Antihypertensive Medication Alter Psychostimulant Behavior?
Sensors 2008, 8(7), 4033-4061; doi:10.3390/s8074033
Received: 29 May 2008 / Revised: 30 June 2008 / Accepted: 2 July 2008 / Published: 4 July 2008
Cited by 5 | PDF Full-text (540 KB) | HTML Full-text | XML Full-text
Abstract
Neuromolecular Imaging (NMI) with novel biosensors enables the selective detection of neurotransmitters in vivo within seconds, on line and in real time. Biosensors remain in place for continuing studies over a period of months. This biotechnological advance is based on conventional electrochemistry; [...] Read more.
Neuromolecular Imaging (NMI) with novel biosensors enables the selective detection of neurotransmitters in vivo within seconds, on line and in real time. Biosensors remain in place for continuing studies over a period of months. This biotechnological advance is based on conventional electrochemistry; the biosensors detect neurotransmitters by electron transfer. Simply stated, biosensors adsorb electrons from each neurotransmitter at specific oxidation potentials; the current derived from electron transfer is proportional to neurotransmitter concentration. Selective electron transfer properties of these biosensors permit the imaging of neurotransmitters, metabolites and precursors. The novel BRODERICK PROBE® biosensors we have developed, differ in formulation and detection capabilities from biosensors/electrodes used in conventional electrochemistry/ voltammetry. In these studies, NMI, specifically, the BRODERICK PROBE® laurate biosensor images neurotransmitter signals within mesolimbic neuronal terminals, nucleus accumbens (NAc); dopamine (DA), serotonin (5-HT), homovanillic acid (HVA) and Ltryptophan (L-TP) are selectively imaged. Simultaneously, we use infrared photobeams to monitor open-field movement behaviors on line with NMI in the same animal subjects. The goals are to investigate integrated neurochemical and behavioral effects of cocaine and caffeine alone and co-administered and further, to use ketanserin to decipher receptor profiles for these psychostimulants, alone and co-administered. The rationale for selecting this medication is: ketanserin (a) is an antihypertensive and cocaine and caffeine produce hypertension and (b) acts at 5-HT2A/2C receptors, prevalent in NAc and implicated in hypertension and cocaine addiction. Key findings are: (a) the moderate dose of caffeine simultaneously potentiates cocaine's neurochemical and behavioral responses. (b) ketanserin simultaneously inhibits cocaine-increased DA and 5-HT release in NAc and open-field behaviors and (c) ketanserin inhibits 5-HT release in NAc and open-field behaviors produced by caffeine, but, surprisingly, acts to increase DA release in NAc. Importantly, the latter effect may be a possible adverse effect of the moderate dose of caffeine in hypertensive patients. Thus, an antihypertensive medication is shown here to play a role in inhibiting brain reward possibly via antihypertensive mechanisms at DA and 5-HT receptor subtypes within DA motor neurons. An explanatory note for the results obtained, is the role likely played by the G Protein Receptor Complex (GPRC) family of proteins. Empirical evidence shows that GPRC dimers, heteromers and heterotrimers may cause cross-talk between distinct signalling cascade pathways in the actions of cocaine and caffeine. Ligand-directed functional selectivity, particularly for ketanserin, in addition to GPRCs, may also cause differential responses. The results promise new therapeutic strategies for drug addiction, brain reward and cardiovascular medicine. Full article
Open AccessArticle A Determination of Metallothionein in Larvae of Freshwater Midges (Chironomus riparius) Using Brdicka Reaction
Sensors 2008, 8(7), 4081-4094; doi:10.3390/s8074081
Received: 31 May 2008 / Revised: 6 July 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Cited by 26 | PDF Full-text (181 KB) | HTML Full-text | XML Full-text
Abstract
Among wide spectrum of biomolecules induced by various stress factors low molecular mass protein called metallothionein (MT) is suitable for assessment of the heavy metal environmental pollution. The aim of this work was to determine the metallothionein and total thiols content in [...] Read more.
Among wide spectrum of biomolecules induced by various stress factors low molecular mass protein called metallothionein (MT) is suitable for assessment of the heavy metal environmental pollution. The aim of this work was to determine the metallothionein and total thiols content in larvae of freshwater midges (Chironomus riparius) sampled from laboratory exposure to cadmium(II) ions and from field studies using differential pulse voltammetry Brdicka reaction. Unique electrochemical instrument, stationary electrochemical analyser Autolab coupled with autosampler, was utilized for the analysis of the samples. The detection limit for MT was evaluated as 5 nM. The larvae exposed to two doses (50 ng/g or 50 μg/g) of cadmium(II) ions for fifteen days under laboratory controlled conditions were at the end of the exposure killed, homogenized and analysed. MT content in control samples was 1.2 μM, in larvae exposed to 50 ng Cd/g it was 2.0 μM and in larvae exposed to 50 μg Cd/g 2.9 μM. Moreover at field study chironomid larvae as well as sediment samples have been collected from eight field sites with different levels of pollution by heavy. The metals content (chromium, nickel, copper, zinc, arsenic, molybdenum, cadmium, tin and lead) in the sediment and or MT content in the chironomid larvae were determined by inductively coupled plasma mass spectrometry or Brdicka reaction, respectively. Full article
Open AccessArticle Comparison of Mercury Distribution Between Liver and Muscle – A Biomonitoring of Fish from Lightly and Heavily Contaminated Localities
Sensors 2008, 8(7), 4095-4109; doi:10.3390/s8074095
Received: 19 January 2008 / Revised: 6 July 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Cited by 36 | PDF Full-text (409 KB) | HTML Full-text | XML Full-text
Abstract
Tissue samples from 1,117 fish of 25 species were collected from 1991 through 1996 at 13 locations along the River Elbe. The principal indicator species were perch (Perca fluviatilis) (n=118), chub (Leuciscus cephalus L.) (n=113) and roach (Rutilus rutilus) (n=138). Mercury (Hg) [...] Read more.
Tissue samples from 1,117 fish of 25 species were collected from 1991 through 1996 at 13 locations along the River Elbe. The principal indicator species were perch (Perca fluviatilis) (n=118), chub (Leuciscus cephalus L.) (n=113) and roach (Rutilus rutilus) (n=138). Mercury (Hg) concentrations in muscle and liver were determined by atomic absorption spectrometry. The liver/muscle index in three indicator species from heavily contaminated and lightly contaminated localities were significantly different. In fish from heavily contaminated localities, Hg was deposited preferentially in the liver (the depository for inorganic and organic forms of Hg), while in lightly contaminated areas, it was deposited preferentially in muscle. Full article
Open AccessCommunication Development of Amperometric Hydrogen Peroxide Sensor Based on Horseradish Peroxidase-Immobilized Poly(Thiophene-co-EpoxyThiophene)
Sensors 2008, 8(7), 4110-4118; doi:10.3390/s8074110
Received: 26 March 2008 / Revised: 3 June 2008 / Accepted: 12 June 2008 / Published: 9 July 2008
Cited by 8 | PDF Full-text (734 KB) | HTML Full-text | XML Full-text
Abstract
A modified electrode for hydrogen peroxide (H2O2) sensing was prepared via thiophene (Th) with epoxy group. Thiophene (EpoxyTh) with epoxy group was synthesized by reaction of 3-bromothiophene and glycidyl methacrylate (GMA) in acetonitrile according to Heck Reaction. The [...] Read more.
A modified electrode for hydrogen peroxide (H2O2) sensing was prepared via thiophene (Th) with epoxy group. Thiophene (EpoxyTh) with epoxy group was synthesized by reaction of 3-bromothiophene and glycidyl methacrylate (GMA) in acetonitrile according to Heck Reaction. The electrocopolymerization of Th and EpoxyTh was performed on the surface of indium tin oxide (ITO) electrode by cycling the potential between -1.0 and +2.5 V in mixture of thiophene (Th) and EpoxyTh. Poly(Th-co- EpoxyTh) grown onto the ITO electrode was successfully confirmed by SEM, AFM, and water contact angle analysis, respectively. Finally, the HRP was immobilized on the surface of poly(Th-co-EpoxyTh) electrode by covalent binding. The amperometric response of the HRP-immobilized poly(Th-co-EpoxyTh) electrode for H2O2 was examined by cyclic voltammetry (CV). The HRP-immobilized poly(Th-co-EpoxyTh) electrode showed linearity from 0.1 to 30 mM H2O2, good reproducibility, and long life time. Full article
Open AccessArticle A Methodology to Validate the InSAR Derived Displacement Field of the September 7th, 1999 Athens Earthquake Using Terrestrial Surveying. Improvement of the Assessed Deformation Field by Interferometric Stacking
Sensors 2008, 8(7), 4119-4134; doi:10.3390/s8074119
Received: 20 March 2008 / Revised: 19 June 2008 / Accepted: 20 June 2008 / Published: 10 June 2008
Cited by 2 | PDF Full-text (1248 KB) | HTML Full-text | XML Full-text
Abstract
The primary objective of this paper is the evaluation of the InSAR derived displacement field caused by the 07/09/1999 Athens earthquake, using as reference an external data source provided by terrestrial surveying along the Mornos river open aqueduct. To accomplish this, a [...] Read more.
The primary objective of this paper is the evaluation of the InSAR derived displacement field caused by the 07/09/1999 Athens earthquake, using as reference an external data source provided by terrestrial surveying along the Mornos river open aqueduct. To accomplish this, a processing chain to render comparable the leveling measurements and the interferometric derived measurements has been developed. The distinct steps proposed include a solution for reducing the orbital and atmospheric interferometric fringes and an innovative method to compute the actual InSAR estimated vertical ground subsidence, for direct comparison with the leveling data. Results indicate that the modeled deformation derived from a series of stacked interferograms, falls entirely within the confidence interval assessed for the terrestrial surveying data. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
Open AccessArticle Satellite Assessment of Bio-Optical Properties of Northern Gulf of Mexico Coastal Waters Following Hurricanes Katrina and Rita
Sensors 2008, 8(7), 4135-4150; doi:10.3390/s8074135
Received: 5 June 2008 / Revised: 18 June 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Cited by 18 | PDF Full-text (3823 KB) | HTML Full-text | XML Full-text
Abstract
The impacts of major tropical storms events on coastal waters include sediment resuspension, intense water column mixing, and increased delivery of terrestrial materials into coastal waters. We examined satellite imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color sensor aboard [...] Read more.
The impacts of major tropical storms events on coastal waters include sediment resuspension, intense water column mixing, and increased delivery of terrestrial materials into coastal waters. We examined satellite imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color sensor aboard the Aqua spacecraft following two major hurricane events: Hurricane Katrina, which made landfall on 29 August 2005, and Hurricane Rita, which made landfall on 24 September. MODIS Aqua true color imagery revealed high turbidity levels in shelf waters immediately following the storms indicative of intense resuspension. However, imagery following the landfall of Katrina showed relatively rapid return of shelf water mass properties to pre-storm conditions. Indeed, MODIS Aqua-derived estimates of diffuse attenuation at 490 nm (K_490) and chlorophyll (chlor_a) from mid-August prior to the landfall of Hurricane Katrina were comparable to those observed in mid-September following the storm. Regions of elevated K_490 and chlor_a were evident in offshore waters and appeared to be associated with cyclonic circulation (cold-core eddies) identified on the basis of sea surface height anomaly (SSHA). Imagery acquired shortly after Hurricane Rita made landfall showed increased water column turbidity extending over a large area of the shelf off Louisiana and Texas, consistent with intense resuspension and sediment disturbance. An interannual comparison of satellite-derived estimates of K_490 for late September and early October revealed relatively lower levels in 2005, compared to the mean for the prior three years, in the vicinity of the Mississippi River birdfoot delta. In contrast, levels above the previous three year mean were observed off Texas and Louisiana 7-10 d after the passage of Rita. The lower values of K_490 near the delta could be attributed to relatively low river discharge during the preceding months of the 2005 season. The elevated levels off Texas and Louisiana were speculated to be due to the presence of fine grain sediment or dissolved materials that remained in the water column following the storm, and may also have been associated with enhanced phytoplankton biomass stimulated by the intense vertical mixing and offshore delivery of shelf water and associated nutrients. This latter view was supported by observations of high chlor_a in association with regions of cyclonic circulation. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle Integrating Physical and Topographic Information Into a Fuzzy Scheme to Map Flooded Area by SAR
Sensors 2008, 8(7), 4151-4164; doi:10.3390/s8074151
Received: 29 May 2008 / Revised: 27 June 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Cited by 34 | PDF Full-text (1675 KB) | HTML Full-text | XML Full-text
Abstract
A flood mapping procedure based on a fuzzy sets theory has been developed. The method is based on the integration of Synthetic Aperture Radar (SAR) measurements with additional data on the inundated area, such as a land cover map and a digital [...] Read more.
A flood mapping procedure based on a fuzzy sets theory has been developed. The method is based on the integration of Synthetic Aperture Radar (SAR) measurements with additional data on the inundated area, such as a land cover map and a digital elevation model (DEM). The information on land cover has allowed us to account for both specular reflection, typical of open water, and double bounce backscattering, typical of forested and urban areas. DEM has been exploited to include simple hydraulic considerations on the dependence of inundation probability on surface characteristics. Contextual information has been taken into account too. The proposed algorithm has been tested on a flood occurred in Italy on November 1994. A pair of ERS-1 images, collected before and after (three days later) the flood, has been used. The results have been compared with the data provided by a ground survey carried out when the flood reached its maximum extension. Despite the temporal mismatch between the survey and the post-inundation SAR image, the comparison has yielded encouraging results, with the 87% of the pixels correctly classified as inundated. Full article
(This article belongs to the Special Issue Sensors for Disaster and Emergency Management Decision Making)
Open AccessArticle Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters
Sensors 2008, 8(7), 4165-4185; doi:10.3390/s8074165
Received: 4 June 2008 / Revised: 17 June 2008 / Accepted: 6 July 2008 / Published: 10 July 2008
Cited by 38 | PDF Full-text (1436 KB) | HTML Full-text | XML Full-text
Abstract
Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at satellite wavebands useful to coastal applications. Global algorithms are also derived for the merged data set (193 stations). The performances of global and local regression algorithms are compared. The best one-band algorithms on all the measurements are obtained at 681 nm using either a polynomial or a power model. The best two-band algorithms are obtained with R412/R620, R443/R670 and R510/R681. Two three-band algorithms based on Rrs620.Rrs681/Rrs412 and Rrs620.Rrs681/Rrs510 also give fair regression statistics. Finally, we propose a global algorithm based on one or three bands: turbidity is first calculated from Rrs681 and then, if < 1 FTU, it is recalculated using an algorithm based on Rrs620.Rrs681/Rrs412. On our data set, this algorithm is suitable for the 0.2-25 FTU turbidity range and for the three sites sampled (mean bias: 3.6 %, rms: 35%, mean quadratic error: 1.4 FTU). This shows that defining global empirical turbidity algorithms in tropical coastal waters is at reach. Full article
Open AccessArticle Kernel Based Nonlinear Dimensionality Reduction and Classification for Genomic Microarray
Sensors 2008, 8(7), 4186-4200; doi:10.3390/s8074186
Received: 4 June 2008 / Revised: 17 June 2008 / Accepted: 6 July 2008 / Published: 15 July 2008
Cited by 3 | PDF Full-text (282 KB) | HTML Full-text | XML Full-text
Abstract
Genomic microarrays are powerful research tools in bioinformatics and modern medicinal research because they enable massively-parallel assays and simultaneous monitoring of thousands of gene expression of biological samples. However, a simple microarray experiment often leads to very high-dimensional data and a huge [...] Read more.
Genomic microarrays are powerful research tools in bioinformatics and modern medicinal research because they enable massively-parallel assays and simultaneous monitoring of thousands of gene expression of biological samples. However, a simple microarray experiment often leads to very high-dimensional data and a huge amount of information, the vast amount of data challenges researchers into extracting the important features and reducing the high dimensionality. In this paper, a nonlinear dimensionality reduction kernel method based locally linear embedding(LLE) is proposed, and fuzzy K-nearest neighbors algorithm which denoises datasets will be introduced as a replacement to the classical LLE’s KNN algorithm. In addition, kernel method based support vector machine (SVM) will be used to classify genomic microarray data sets in this paper. We demonstrate the application of the techniques to two published DNA microarray data sets. The experimental results confirm the superiority and high success rates of the presented method. Full article
Open AccessArticle Determination of Lamotrigine in Pharmaceutical Preparations by Adsorptive Stripping Voltammetry Using Screen Printed Electrodes
Sensors 2008, 8(7), 4201-4212; doi:10.3390/s8074201
Received: 5 June 2008 / Revised: 25 June 2008 / Accepted: 10 July 2008 / Published: 15 July 2008
Cited by 20 | PDF Full-text (98 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a procedure that has been optimized for the determination of lamotrigine by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV) using carbon screen-printed electrodes (CSPE) and mercury coated carbon screen-printed electrodes. Selection of the experimental parameters was made using experimental design [...] Read more.
This paper describes a procedure that has been optimized for the determination of lamotrigine by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV) using carbon screen-printed electrodes (CSPE) and mercury coated carbon screen-printed electrodes. Selection of the experimental parameters was made using experimental design methodology. The detection limit found was 5.0 x 10-6 M and 2.0 x 10-6 M for the non modified and Hg modified CSPE, respectively. In terms of reproducibility, the precision of the above mentioned methods was calculated in %RSD values at 9.83% for CSPE and 2.73% for Hg-CSPE. The Hg-coated CSPEs developed in this work were successfully applied in the determination of lamotrigine in pharmaceutical preparations. Full article
Open AccessArticle Short-term Influences on Suspended Particulate Matter Distribution in the Northern Gulf of Mexico: Satellite and Model Observations
Sensors 2008, 8(7), 4249-4264; doi:10.3390/s8074249
Received: 23 May 2008 / Revised: 29 June 2008 / Accepted: 7 July 2008 / Published: 15 July 2008
Cited by 14 | PDF Full-text (954 KB) | HTML Full-text | XML Full-text
Abstract
Energetic meteorological events such as frontal passages and hurricanes often impact coastal regions in the northern Gulf of Mexico that influence geochemical processes in the region. Satellite remote sensing data such as winds from QuikSCAT, suspended particulate matter (SPM) concentrations derived from [...] Read more.
Energetic meteorological events such as frontal passages and hurricanes often impact coastal regions in the northern Gulf of Mexico that influence geochemical processes in the region. Satellite remote sensing data such as winds from QuikSCAT, suspended particulate matter (SPM) concentrations derived from SeaWiFS and the outputs (sea level and surface ocean currents) of a nested navy coastal ocean model (NCOM) were combined to assess the effects of frontal passages between 23-28 March 2005 on the physical properties and the SPM characteristics in the northern Gulf of Mexico. Typical changes in wind speed and direction associated with frontal passages were observed in the latest 12.5 km wind product from QuikSCAT with easterly winds before the frontal passage undergoing systematic shifts in direction and speed and turning northerly, northwesterly during a weak and a strong front on 23 and 27 March, respectively. A quantitative comparison of model sea level results with tide gauge observations suggest better correlations near the delta than in the western part of the Gulf with elevated sea levels along the coast before the frontal passage and a large drop in sea level following the frontal passage on 27 March. Model results of surface currents suggested strong response to wind forcing with westward and onshore currents before the frontal passage reversing into eastward, southeastward direction over a six day period from 23 to 28 March 2005. Surface SPM distribution derived from SeaWiFS ocean color data for two clear days on 23 and 28 March 2005 indicated SPM plumes to be oriented with the current field with increasing concentrations in nearshore waters due to resuspension and discharge from the rivers and bays and its seaward transport following the frontal passage. The backscattering spectral slope γ, a parameter sensitive to particle size distribution also indicated lower γ values (larger particles) in nearshore waters that decreased offshore (smaller particles). The use of both satellite and model results revealed the strong interactions between physical processes and the surface particulate field in response to the frontal passage in a large riverdominated coastal margin. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems
Sensors 2008, 8(7), 4265-4281; doi:10.3390/s8074265
Received: 31 May 2008 / Revised: 7 July 2008 / Accepted: 8 July 2008 / Published: 15 July 2008
Cited by 5 | PDF Full-text (243 KB) | HTML Full-text | XML Full-text
Abstract
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless [...] Read more.
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting crosslayer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An eventdriven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN. Full article
Open AccessArticle Detection of Carcinoembryonic Antigens Using a Surface Plasmon Resonance Biosensor
Sensors 2008, 8(7), 4282-4295; doi:10.3390/s8074282
Received: 29 May 2008 / Revised: 7 July 2008 / Accepted: 9 July 2008 / Published: 18 July 2008
Cited by 14 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Carcinoembryonic antigen (CEA) is an oncofoetal cell-surface glycoprotein that serves as an important tumor marker for colorectal and some other carcinomas. In this work, a CEA immunoassay using a surface plasmon resonance (SPR) biosensor has been developed. SPR could provide label-free, real-time [...] Read more.
Carcinoembryonic antigen (CEA) is an oncofoetal cell-surface glycoprotein that serves as an important tumor marker for colorectal and some other carcinomas. In this work, a CEA immunoassay using a surface plasmon resonance (SPR) biosensor has been developed. SPR could provide label-free, real-time detection with high sensitivity, though its ability to detect CEA in human serum was highly dependent on the analytical conditions employed. We investigated the influences of various analytical conditions including immobilization methods for anti-CEA antibody and composition of sensor surface on the selective and sensitive detection of CEA. The results show that anti-CEA antibody immobilized via Protein A or Protein G caused a large increase in the resonance signal upon injection of human serum due to the interactions with IgGs in serum, while direct covalent immobilization of anti-CEA antibody could substantially reduce it. An optimized protocol based on further kinetic analysis and the use of 2nd and 3rd antibodies for the sandwich assay allowed detecting spiked CEA in human serum as low as 25 ng/mL. Furthermore, a self-assembled monolayer of mixed ethylene-glycol terminated alkanethiols on gold was found to have a comparable ability in detecting CEA as CM5 with thick dextran matrix and C1 with short flat layer on gold. Full article
(This article belongs to the Special Issue Bioanalysis in Vivo/in Vitro)
Open AccessArticle A Fixed-Threshold Approach to Generate High-Resolution Vegetation Maps for IKONOS Imagery
Sensors 2008, 8(7), 4308-4317; doi:10.3390/s8074308
Received: 18 May 2008 / Revised: 16 July 2008 / Accepted: 18 July 2008 / Published: 25 July 2008
Cited by 7 | PDF Full-text (1608 KB) | HTML Full-text | XML Full-text
Abstract
Vegetation distribution maps from remote sensors play an important role in urban planning, environmental protecting and related policy making. The normalized difference vegetation index (NDVI) is the most popular approach to generate vegetation maps for remote sensing imagery. However, NDVI is usually [...] Read more.
Vegetation distribution maps from remote sensors play an important role in urban planning, environmental protecting and related policy making. The normalized difference vegetation index (NDVI) is the most popular approach to generate vegetation maps for remote sensing imagery. However, NDVI is usually used to generate lower resolution vegetation maps, and particularly the threshold needs to be chosen manually for extracting required vegetation information. To tackle this threshold selection problem for IKONOS imagery, a fixed-threshold approach is developed in this work, which integrates with an extended Tasseled Cap transformation and a designed image fusion method to generate high-resolution (1-meter) vegetation maps. Our experimental results are promising and show it can generate more accurate and useful vegetation maps for IKONOS imagery. Full article
Open AccessArticle Textile Pressure Sensor Made of Flexible Plastic Optical Fibers
Sensors 2008, 8(7), 4318-4329; doi:10.3390/s8074318
Received: 2 July 2008 / Revised: 23 July 2008 / Accepted: 23 July 2008 / Published: 25 July 2008
Cited by 41 | PDF Full-text (807 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area [...] Read more.
In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area of the textile is applied to these fibers they change their cross section reversibly, due to their elastomeric character, and a simultaneous change in transmitted light intensity can be detected. We have successfully manufactured two different woven samples with fibers of 0.51 and 0.98 mm diameter in warp and weft direction, forming a pressure sensitive matrix. Determining their physical behavior when a force is applied shows that pressure measurements are feasible. Their usable working range is between 0 and 30 N. Small drifts in the range of 0.2 to 4.6%, over 25 load cycles, could be measured. Finally, a sensor array of 2 x 2 optical fibers was tested for sensitivity, spatial resolution and light coupling between fibers at intersections. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Switzerland)
Open AccessArticle Electrochemical Sensing and Assessment of Parabens in Hydro- Alcoholic Solutions and Water Using a Boron-Doped Diamond Electrode
Sensors 2008, 8(7), 4330-4349; doi:10.3390/s8074330
Received: 4 July 2008 / Revised: 17 July 2008 / Accepted: 17 July 2008 / Published: 25 July 2008
Cited by 26 | PDF Full-text (5891 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the electrochemical behaviour of several parabens preservatives, i.e. esters of p-hydroxybenzoic acid, methyl-, ethyl- and propyl-4-hydroxybenzoates as methyl-, ethyl- and propyl-parabens (MB, EB, and PB), has been investigated at a commercial boron-doped diamond electrode (BDDE), especially in the anodic [...] Read more.
In this paper, the electrochemical behaviour of several parabens preservatives, i.e. esters of p-hydroxybenzoic acid, methyl-, ethyl- and propyl-4-hydroxybenzoates as methyl-, ethyl- and propyl-parabens (MB, EB, and PB), has been investigated at a commercial boron-doped diamond electrode (BDDE), especially in the anodic potential range, in both hydro-alcoholic and aqueous media. The cyclic voltammetric and chronoamperometric measurements yielded calibration plots with very good linearity (R2 between 0.990 and 0.998) and high sensitivity, useful for detection and analytical applications. The determination of the characteristics of individual compounds, of an “overall paraben index”, the assessment of the stability and the saturation solubility in water, and the amperometric sensing and determination in double distilled, tap and river water matrix of the relatively slightly soluble investigated parabens have been carried out using electrochemical alternative. Estimated water solubility was correlated with the octanol-water partition coefficient. Several ideas regarding stability and persistence of the presumptive eco-toxic investigated preservatives in the environment or water systems have been adjacently discussed. Full article
Open AccessArticle The Image Transceiver Device: Studies of Improved Physical Design
Sensors 2008, 8(7), 4350-4364; doi:10.3390/s8074350
Received: 26 June 2008 / Revised: 17 July 2008 / Accepted: 21 July 2008 / Published: 25 July 2008
Cited by 4 | PDF Full-text (170 KB) | HTML Full-text | XML Full-text
Abstract
The Image Transceiver Device (ITD) design is based on combining LCOS micro-display, image processing tools and back illuminated APS imager in single CMOS chip [1]. The device is under development for Head-Mounted Display applications in augmented and virtual reality systems. The main [...] Read more.
The Image Transceiver Device (ITD) design is based on combining LCOS micro-display, image processing tools and back illuminated APS imager in single CMOS chip [1]. The device is under development for Head-Mounted Display applications in augmented and virtual reality systems. The main issues with the present design are a high crosstalk of the backside imager and the need to shield the pixel circuitry from the photocharges generated in the silicon substrate. In this publication we present a modified, “deep p-well” ITD pixel design, which provides a significantly reduced crosstalk level, as well as an effective shielding of photo-charges for the pixel circuitry. The simulation performed using Silvaco software [ATLAS Silicon Device Simulator, Ray Trace and Light Absorption programs, Silvaco International, 1998] shows that the new approach provides high photo response and allows increasing the optimal thickness of the die over and above the 10-15 micrometers commonly used for back illuminated imaging devices, thereby improving its mechanical ruggedness following the thinning process and also providing a more efficient absorption of the long wavelength photons. The proposed deep p-well pixel structure is also a technology solution for the fabrication of high performance back illuminated CMOS image sensors. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)
Open AccessArticle Detection of Hidden Hostile/Terrorist Groups in Harsh Territories by Using Animals as Mobile Biological Sensors
Sensors 2008, 8(7), 4365-4383; doi:10.3390/s8074365
Received: 2 July 2008 / Revised: 22 July 2008 / Accepted: 22 July 2008 / Published: 25 July 2008
Cited by 3 | PDF Full-text (1063 KB) | HTML Full-text | XML Full-text
Abstract
Terrorism is the greatest threat to national security and cannot be defeated by conventional military force alone. In critical areas such as Iraq, Afghanistan and Turkey, regular forces cannot reach these hostile/terrorist groups, the instigators of terrorism. These groups have a clear [...] Read more.
Terrorism is the greatest threat to national security and cannot be defeated by conventional military force alone. In critical areas such as Iraq, Afghanistan and Turkey, regular forces cannot reach these hostile/terrorist groups, the instigators of terrorism. These groups have a clear understanding of the relative ineffectiveness of counter-guerrilla operations and rely on guerrilla warfare to avoid major combat as their primary means of continuing the conflict with the governmental structures. In Internal Security Operations, detection of terrorist and hostile groups in their hiding places such as caves, lairs, etc. can only be achieved by professionally trained people such as Special Forces or intelligence units with the necessary experience and tools suitable for collecting accurate information in these often harsh, rugged and mountainous countries. To assist these forces, commercial micro-sensors with wireless interfaces could be utilized to study and monitor a variety of phenomena and environments from a certain distance for military purposes. In order to locate hidden terrorist groups and enable more effective use of conventional military resources, this paper proposes an active remote sensing model implanted into animals capable of living in these environments. By using these mobile sensor devices, improving communications for data transfer from the source, and developing better ways to monitor and detect threats, terrorist ability to carry out attacks can be severely disrupted. Full article
Open AccessCommunication ST Quartz Acoustic Wave Sensors with Sectional Guiding Layers
Sensors 2008, 8(7), 4384-4391; doi:10.3390/s80704384
Received: 10 June 2008 / Revised: 23 July 2008 / Accepted: 24 July 2008 / Published: 25 July 2008
Cited by 1 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
We report the effect of removing a section of guiding layer from the propagation paths of ST-quartz Love wave sensors; this offers the ease of fabrication of a polymer guiding layer whilst retaining the native surface of the quartz which may then [...] Read more.
We report the effect of removing a section of guiding layer from the propagation paths of ST-quartz Love wave sensors; this offers the ease of fabrication of a polymer guiding layer whilst retaining the native surface of the quartz which may then be used for the attachment of a sensitizing layer. Data is presented for the rigid and viscous loading, which indicates a small reduction in mass sensitivity compared to a Love wave device. Biosensing capabilities of these discontinuous ‘sectional’ guiding layer devices are demonstrated using protein adsorption from solution. Full article
Open AccessArticle PAU/RAD: Design and Preliminary Calibration Results of a New L-Band Pseudo-Correlation Radiometer Concept
Sensors 2008, 8(7), 4392-4412; doi:10.3390/s8074392
Received: 3 June 2008 / Revised: 14 July 2008 / Accepted: 25 July 2008 / Published: 28 July 2008
Cited by 5 | PDF Full-text (1465 KB) | HTML Full-text | XML Full-text
Abstract
The Passive Advanced Unit (PAU) for ocean monitoring is a new type of instrument that combines in a single receiver and without time multiplexing, a polarimetric pseudo-correlation microwave radiometer at L-band (PAU-RAD) and a GPS reflectometer (PAU-GNSS/R). These instruments in conjunction with [...] Read more.
The Passive Advanced Unit (PAU) for ocean monitoring is a new type of instrument that combines in a single receiver and without time multiplexing, a polarimetric pseudo-correlation microwave radiometer at L-band (PAU-RAD) and a GPS reflectometer (PAU-GNSS/R). These instruments in conjunction with an infra-red radiometer (PAU-IR) will respectively provide the sea surface temperature and the sea state information needed to accurately retrieve the sea surface salinity from the radiometric measurements. PAU will consist of an array of 4x4 receivers performing digital beamforming and polarization synthesis both for PAU-RAD and PAU-GNSS/R. A concept demonstrator of the PAU instrument with only one receiver has been implemented (PAU-One Receiver or PAU-OR). PAU-OR has been used to test and tune the calibration algorithms that will be applied to PAU. This work describes in detail PAU-OR’s radiometer calibration algorithms and their performance. Full article
Open AccessArticle Nanobioengineering and Characterization of a Novel Estrogen Receptor Biosensor
Sensors 2008, 8(7), 4413-4428; doi:10.3390/s8074413
Received: 12 June 2008 / Revised: 15 July 2008 / Accepted: 25 July 2008 / Published: 28 July 2008
Cited by 3 | PDF Full-text (625 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We constructed an original supramolecular assembly on a surface of sensor composed of an innovative combination of an engineered cytochrome b5 and a modified nucleic acid bound to a synthetic lipid hemimembrane. The protein/DNA block, called (PDNA) 2, was synthesized and purified [...] Read more.
We constructed an original supramolecular assembly on a surface of sensor composed of an innovative combination of an engineered cytochrome b5 and a modified nucleic acid bound to a synthetic lipid hemimembrane. The protein/DNA block, called (PDNA) 2, was synthesized and purified before its immobilization onto a hybrid bilayer reconstituted on a gold surface. Surface plasmon resonance (SPR) and atomic force microscopy (AFM) were engaged in parallel on the same substrates in order to better understand dynamic events that occur at the surface of the biosensor. Good correlations were obtained in terms of specificity and reversibility. These findings allow us to present a first application of such biosensor in the study of the interaction processes between nuclear receptor and DNA. Full article
Open AccessArticle Multi-Source Remotely Sensed Data Combination: Projection Transformation Gap-Fill Procedure
Sensors 2008, 8(7), 4429-4440; doi:10.3390/s8074429
Received: 17 June 2008 / Revised: 20 July 2008 / Accepted: 25 July 2008 / Published: 29 July 2008
Cited by 15 | PDF Full-text (964 KB) | HTML Full-text | XML Full-text
Abstract
In this work a new gap-fill technique entitled projection transformation has been developed and used for filling missed parts of remotely sensed imagery. In general techniques for filling missed area of an image are broken down into three main categories: multi-source techniques [...] Read more.
In this work a new gap-fill technique entitled projection transformation has been developed and used for filling missed parts of remotely sensed imagery. In general techniques for filling missed area of an image are broken down into three main categories: multi-source techniques that take the advantages of other data sources (e.g. using cloud free images to reconstruct the cloudy areas of other images); the second ones fabricate the gap areas using non-gapped parts of an image itself, this group of techniques are referred to as single-source gap-fill procedures; and third group contains methods that make up a combination of both mentioned techniques, therefore they are called hybrid gap-fill procedures. Here a new developed multi-source methodology called projection transformation for filling a simulated gapped area in the Landsat7/ETM+ imagery is introduced. The auxiliary imagery to filling the gaps is an earlier obtained L7/ETM+ imagery. Ability of the technique was evaluated from three points of view: statistical accuracy measuring, visual comparison, and post classification accuracy assessment. These evaluation indicators are compared to the results obtained from a commonly used technique by the USGS as Local Linear Histogram Matching (LLHM) [1]. Results show the superiority of our technique over LLHM in almost all aspects of accuracy. Full article
Open AccessArticle Integrating Remote Sensing Information Into A Distributed Hydrological Model for Improving Water Budget Predictions in Large-scale Basins through Data Assimilation
Sensors 2008, 8(7), 4441-4465; doi:10.3390/s8074441
Received: 28 May 2008 / Revised: 10 July 2008 / Accepted: 25 July 2008 / Published: 29 July 2008
Cited by 16 | PDF Full-text (940 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates whether remote sensing evapotranspiration estimates can be integrated by means of data assimilation into a distributed hydrological model for improving the predictions of spatial water distribution over a large river basin with an area of 317,800 km2. A series [...] Read more.
This paper investigates whether remote sensing evapotranspiration estimates can be integrated by means of data assimilation into a distributed hydrological model for improving the predictions of spatial water distribution over a large river basin with an area of 317,800 km2. A series of available MODIS satellite images over the Haihe River basin in China are used for the year 2005. Evapotranspiration is retrieved from these 1×1 km resolution images using the SEBS (Surface Energy Balance System) algorithm. The physically-based distributed model WEP-L (Water and Energy transfer Process in Large river basins) is used to compute the water balance of the Haihe River basin in the same year. Comparison between model-derived and remote sensing retrieval basin-averaged evapotranspiration estimates shows a good piecewise linear relationship, but their spatial distribution within the Haihe basin is different. The remote sensing derived evapotranspiration shows variability at finer scales. An extended Kalman filter (EKF) data assimilation algorithm, suitable for non-linear problems, is used. Assimilation results indicate that remote sensing observations have a potentially important role in providing spatial information to the assimilation system for the spatially optical hydrological parameterization of the model. This is especially important for large basins, such as the Haihe River basin in this study. Combining and integrating the capabilities of and information from model simulation and remote sensing techniques may provide the best spatial and temporal characteristics for hydrological states/fluxes, and would be both appealing and necessary for improving our knowledge of fundamental hydrological processes and for addressing important water resource management problems. Full article
Open AccessArticle Cantilever measurements of surface stress, surface reconstruction, film stress and magnetoelastic stress of monolayers
Sensors 2008, 8(7), 4466-4486; doi:10.3390/s8074466
Received: 4 March 2008 / Revised: 16 May 2008 / Accepted: 16 May 2008 / Published: 29 July 2008
Cited by 16 | PDF Full-text (879 KB) | HTML Full-text | XML Full-text
Abstract
We review the application of cantilever-based stress measurements in surface science and magnetism. The application of thin (thickness appr. 0.1 mm) single crystalline substrates as cantilevers has been used successfully to measure adsorbate-induced surface stress changes, lattice misfit induced film stress, and [...] Read more.
We review the application of cantilever-based stress measurements in surface science and magnetism. The application of thin (thickness appr. 0.1 mm) single crystalline substrates as cantilevers has been used successfully to measure adsorbate-induced surface stress changes, lattice misfit induced film stress, and magneto-elastic stress of ferromagnetic monolayers. Surface stress changes as small as 0.01 N/m can be readily measured, and this translates into a sensitivity for adsorbate-coverage well below 0.01 of one layer. Stress as large as several GPa, beyond the elasticity limits of high strength materials, is measured, and it is ascribed to the lattice misfit between film and substrate. Our results point at the intimate relation between surface stress and surface reconstruction, stress-induced structural changes in epitaxially strained films, and strain-induced modifications of the magneto-elastic coupling in ferromagnetic monolayers. Full article

Review

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Open AccessReview Bacterial Biosensors for Measuring Availability of Environmental Pollutants
Sensors 2008, 8(7), 4062-4080; doi:10.3390/s8074062
Received: 22 May 2008 / Revised: 6 July 2008 / Accepted: 9 July 2008 / Published: 10 July 2008
Cited by 35 | PDF Full-text (726 KB) | HTML Full-text | XML Full-text
Abstract
Traditionally, pollution risk assessment is based on the measurement of a pollutant’s total concentration in a sample. The toxicity of a given pollutant in the environment, however, is tightly linked to its bioavailability, which may differ significantly from the total amount. Physico-chemical [...] Read more.
Traditionally, pollution risk assessment is based on the measurement of a pollutant’s total concentration in a sample. The toxicity of a given pollutant in the environment, however, is tightly linked to its bioavailability, which may differ significantly from the total amount. Physico-chemical and biological parameters strongly influence pollutant fate in terms of leaching, sequestration and biodegradation. Bacterial sensorreporters, which consist of living micro-organisms genetically engineered to produce specific output in response to target chemicals, offer an interesting alternative to monitoring approaches. Bacterial sensor-reporters detect bioavailable and/or bioaccessible compound fractions in samples. Currently, a variety of environmental pollutants can be targeted by specific biosensor-reporters. Although most of such strains are still confined to the lab, several recent reports have demonstrated utility of bacterial sensing-reporting in the field, with method detection limits in the nanomolar range. This review illustrates the general design principles for bacterial sensor-reporters, presents an overview of the existing biosensor-reporter strains with emphasis on organic compound detection. A specific focus throughout is on the concepts of bioavailability and bioaccessibility, and how bacteria-based sensing-reporting systems can help to improve our basic understanding of the different processes at work. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Switzerland)
Open AccessReview On the Soil Roughness Parameterization Problem in Soil Moisture Retrieval of Bare Surfaces from Synthetic Aperture Radar
Sensors 2008, 8(7), 4213-4248; doi:10.3390/s8074213
Received: 22 May 2008 / Revised: 30 May 2008 / Accepted: 25 June 2008 / Published: 15 July 2008
Cited by 124 | PDF Full-text (254 KB) | HTML Full-text | XML Full-text
Abstract
Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless [...] Read more.
Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar (SAR))
Open AccessReview Protein Detection with Aptamer Biosensors
Sensors 2008, 8(7), 4296-4307; doi:10.3390/s8074296
Received: 15 June 2008 / Revised: 7 July 2008 / Accepted: 21 July 2008 / Published: 23 July 2008
Cited by 105 | PDF Full-text (87 KB) | HTML Full-text | XML Full-text
Abstract
Aptamers have been developed for different applications. Their use as new biological recognition elements in biosensors promises progress for fast and easy detection of proteins. This new generation of biosensor (aptasensors) will be more stable and well adapted to the conditions of [...] Read more.
Aptamers have been developed for different applications. Their use as new biological recognition elements in biosensors promises progress for fast and easy detection of proteins. This new generation of biosensor (aptasensors) will be more stable and well adapted to the conditions of real samples because of the specific properties of aptamers. Full article

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