The Experts below are selected from a list of 15822 Experts worldwide ranked by ideXlab platform
Andremichel Loiseau - One of the best experts on this subject based on the ideXlab platform.
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C6 aldehydes and alcohols), which contribute significantly to the “green” flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate techniqu...
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C(6) aldehydes and alcohols), which contribute significantly to the "green" flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate technique for routine quality control due to its operational simplicity, repeatability, and low cost.
Francisco J. Arregui - One of the best experts on this subject based on the ideXlab platform.
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optical fiber humidity sensors based on localized surface plasmon resonance lspr and lossy mode resonance lmr in overlays loaded with silver nanoparticles
Sensors and Actuators B-chemical, 2012Co-Authors: Pedro J. Rivero, Javier Goicoechea, Aitor Urrutia, Francisco J. ArreguiAbstract:Abstract In this work, it is presented for the first time the fabrication and characterization of a novel optical fiber humidity sensor based on both Lossy-mode resonance (LMR) and Localized Surface Plasmon Resonance (LSPR). Those resonances were created using Layer-by-Layer (LbL) Polymeric Coating loaded with Ag nanoparticles (Ag NPs) and fabricated onto an optical fiber core. Firstly, it was observed a LSPR attenuation band, inherent to the presence of the Ag NPs in the Coating. This LSPR band showed a slight intensity variation with Relative Humidity (RH) changes but no significant wavelength dependence was observed. Otherwise several LMR attenuation bands were observed in the 400–1100 nm spectral range as the thickness Coating was increased. The LMR maxima depend strongly on the thickness and refractive index of the LbL overlay, and therefore, they show a strong wavelength response to Relative Humidity (RH) changes. A wavelength-based optical humidity sensor was achieved and the dynamic range (42.4 nm), transfer function, response time (476 ms and 447 ms for rise/fall respectively) were characterized. The results confirm that this sensor could be used even for monitoring human breathing.
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optical fiber ph sensor based on lossy mode resonances by means of thin Polymeric Coatings
Sensors and Actuators B-chemical, 2011Co-Authors: Carlos R. Zamarreño, Miguel Hernaez, Ignacio R. Matias, I Del Villar, Francisco J. ArreguiAbstract:Abstract This work describes the fabrication of an optical fiber sensor with spectral response to pH based on the deposition of a thin Polymeric Coating on an optical fiber core. If the thin Polymeric Coating has a high refractive index real part and a non-null imaginary part, this permits a coupling of light to the modes guided in the Polymeric Coating originating optical resonances. These resonances are named by some authors as lossy-mode resonances (LMR) or guided-mode resonances. Moreover, the location of the resonances in the optical spectrum varies as a function of the Coating thickness and refractive index. Hence, the utilization of the well-known poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) pH sensitive Polymeric Coating that presents a variation of the thickness with the pH of the solution (known as swelling/deswelling behaviour) permits the fabrication of optical fiber pH sensors based on wavelength detection. The fabrication of ready-to-use devices requires considering several aspects such as the adequate Polymeric Coating thickness or the selection of the resonance to be monitored. As a result, LMR-based optical fiber pH sensors with accuracy of ±0.001 pH units and an average sensitivity of 0.027 pH units/nm within the range between pH 3 and pH 6 have been obtained after an adequate design.
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optical fiber ph sensor fabrication by means of indium tin oxide coated optical fiber refractometers
Physica Status Solidi (c), 2010Co-Authors: Carlos R. Zamarreño, Francisco J. Arregui, Ignacio Del Villar, M Hernaez, Carlos Fernandezvaldivielso, Ignacio R. MatiasAbstract:In this work, the fabrication of a novel optical fiber pH sensor is described. This optical fiber pH sensor is based on the utilization of a pH sensitive Polymeric Coating fabricated onto indium tin oxide coated optical fiber refractometers. The pH of the external medium modifies the thickness of the Polymeric Coating and hence the effective refractive index. Thus, ITO coated optical fiber refractometers based on electromagnetic resonances are used as suitable transducers in order to monitor the variations of the pH in the surrounding medium. The fabricated devices permit wavelength based pH detection in the near infra-red region, showing high sensitivity (17.5 nm/pH unit) and fast response. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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tunable humidity sensor based on ito coated optical fiber
Sensors and Actuators B-chemical, 2010Co-Authors: Carlos R. Zamarreño, Ignacio R. Matias, Ignacio Del Villar, M Hernaez, Francisco J. ArreguiAbstract:Abstract Here, it is presented the fabrication and characterization of a new tunable humidity sensor based on ITO-coated optical fiber. A thin nanostructurated multilayer Polymeric film sensitive to humidity is deposited onto the ITO layer. The device is characterized by means of a resonance in the infrared region. Resonance wavelength variations of 600 nm have been recorded during the multilayer fabrication process. The thickness of the Polymeric Coating was adjusted to operate on the point of maximum variation of the resonance wavelength per refractive index unit (RIU) in order to take advantage of the high sensitivity of these resonance based devices. The precise thickness control was achieved by using the layer-by-layer (LbL) deposition technique. The quality of the device is proved experimentally with a sensitivity improvement of a factor four if the tuned optical fiber sensor is used instead of the non-tuned one.
Jeanfrancois Cavalli - One of the best experts on this subject based on the ideXlab platform.
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C6 aldehydes and alcohols), which contribute significantly to the “green” flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate techniqu...
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C(6) aldehydes and alcohols), which contribute significantly to the "green" flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate technique for routine quality control due to its operational simplicity, repeatability, and low cost.
Marcus Newborough - One of the best experts on this subject based on the ideXlab platform.
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minimising frost growth on cold surfaces exposed to humid air by means of crosslinked hydrophilic Polymeric Coatings
Applied Thermal Engineering, 2000Co-Authors: E U Okoroafor, Marcus NewboroughAbstract:Abstract Experiments have shown that frost growth on cold surfaces exposed to warm humid air streams can be reduced significantly by means of crosslinked hydrophilic Polymeric Coatings. This derives from the ability of these materials, under frosting conditions, to absorb available water, and hence retard the growth of frost when compared to an uncoated metallic surface. The extent of reduction of frost growth appeared to vary with the water absorbing potential of the polymer-coat, as well as its water content prior to frosting. In general, measurements in over two hours of testing, indicated that the reduction in frost growth rate and subsequently frost thickness lies in the range, 10–30%. The absorbed water improves the thermal conductivity of the Polymeric Coating. This, consequently, lowers the total thermal resistance between the air stream and the cold plate, and hence retards the frost surface temperature in its rise towards 0°C, an effect that would prolong the effective operation time of the thermal process before there is need for defrosting. Further observations made in this study tend to suggest that the nature of the frost formed with an air stream of low relative humidity (RH) differed from that resulting from a high RH air stream.
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minimising frost growth on cold surfaces exposed to humid air by means of crosslinked hydrophilic Polymeric Coatings
Applied Thermal Engineering, 2000Co-Authors: E U Okoroafor, Marcus NewboroughAbstract:Abstract Experiments have shown that frost growth on cold surfaces exposed to warm humid air streams can be reduced significantly by means of crosslinked hydrophilic Polymeric Coatings. This derives from the ability of these materials, under frosting conditions, to absorb available water, and hence retard the growth of frost when compared to an uncoated metallic surface. The extent of reduction of frost growth appeared to vary with the water absorbing potential of the polymer-coat, as well as its water content prior to frosting. In general, measurements in over two hours of testing, indicated that the reduction in frost growth rate and subsequently frost thickness lies in the range, 10–30%. The absorbed water improves the thermal conductivity of the Polymeric Coating. This, consequently, lowers the total thermal resistance between the air stream and the cold plate, and hence retards the frost surface temperature in its rise towards 0°C, an effect that would prolong the effective operation time of the thermal process before there is need for defrosting. Further observations made in this study tend to suggest that the nature of the frost formed with an air stream of low relative humidity (RH) differed from that resulting from a high RH air stream.
X Fernandez - One of the best experts on this subject based on the ideXlab platform.
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C6 aldehydes and alcohols), which contribute significantly to the “green” flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate techniqu...
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comparison of static headspace headspace solid phase microextraction headspace sorptive extraction and direct thermal desorption techniques on chemical composition of french olive oils
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Jeanfrancois Cavalli, X Fernandez, Louisette Lizzanicuvelier, Andremichel LoiseauAbstract:Static headspace (SHS), headspace solid phase microextraction (HS-SPME), headspace sorptive extraction (HSSE), and direct thermal desorption (DTD) were applied to the analysis of four French virgin olive oils from Corsica. More than 60 compounds were isolated and characterized by GC-RI and GC-MS. SHS was not suited to the characterization of olive oil volatile compounds because of low sensitivity. The SPME and HSSE techniques were successfully applied to olive oil headspace analysis. Both methods allow the characterization of volatile compounds (mainly C(6) aldehydes and alcohols), which contribute significantly to the "green" flavor note of virgin olive oils. The PDMS stir bar showed a higher concentration capacity than a DVB/CAR/PDMS SPME fiber due to the higher volume of Polymeric Coating. DTD was a very good tool for extracting volatile and especially semivolatile compounds, such as sesquiterpenes, but requires a significant investment like that for HSSE. Finally, SPME may be a more appropriate technique for routine quality control due to its operational simplicity, repeatability, and low cost.