| 1. |
- Aghoutane, Youssra, et al.
(författare)
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Development of a molecularly imprinted polymer electrochemical sensor and its application for sensitive detection and determination of malathion in olive fruits and oils
- 2020
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 132
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Tidskriftsartikel (refereegranskat)abstract
- Malathion (MAL) is an organophosphorus (OP) insecticide. It is a cholinesterase inhibitor, 15 which can pose serious health and environmental problems. In this study, a sensitive and 16 selective molecular imprinted polymer (MIP) based on screen-printed gold electrodes (Au-17 SPE) for MAL detection in olive oils and fruits, was devised. The MIP sensor was prepared 18 using acrylamide as the functional monomer and MAL as the template. Subsequently, the 19 morphology of the electrode surface was studied by scanning electron microscopy (SEM) and 20 atomic force microscopy (AFM). The electrochemical characterization of the developed MIP 21 sensor was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), 22 and electrochemical impedance spectroscopy (EIS) techniques. The operational repeatability 23 and stability of the sensor were studied. It was found to have a dynamic concentration range 24 of (0.1 pg mL-1-1000 pg mL-1) and a low limit of detection (LOD) of 0.06 pg mL-1. 25 Furthermore, the sensor was employed to determine MAL content in olive oil with a recovery 26 rate of 87.9% and a relative standard deviation of 8%. It was successfully applied for MAL 27 determination in real samples and promise to open new opportunities for the detection of OP 28 pesticides residues in various food products, as well as in environmental applications.
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| 2. |
- Bengtsson, F., et al.
(författare)
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Alkali ion diffusion and structure of chemically strengthened TiO2 doped soda-lime silicate glass
- 2022
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 586, s. 121564-121564
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion kinetics and structural properties of chemically strengthened titania-doped soda-lime silicate glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry. The glasses were ion exchanged, whereby Na+ in the glass was replaced by K+ in a molten salt bath, at four different treatment temperatures between 350 and 500 °C. The alkali diffusion coefficient, DK-Na, and corresponding activation energy were calculated to be between 3.26×10−12 and 4.47×10−11 cm2s−1 and between 101.1 kJmol−1 and 105.6 kJmol−1, respectively. DK-Na was observed to decrease as the TiO2 concentration was increased. Raman analysis showed Q3-silicate species with different bond lengths, which was attributed to surface compressive stresses, and increasing Si-O-Si bond angle with increasing ion exchange temperature. Ti3+ ions exist as a minor species in the glasses and its concentration depends on the TiO2 content. Deconvolution of the optical absorption spectra reveals Jahn-Teller compressive distortion of the Ti3+ octahedral coordination.
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| 3. |
- Chai, Zhigang, et al.
(författare)
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Ni–Ag Nanostructure-Modified Graphitic Carbon Nitride for Enhanced Performance of Solar-Driven Hydrogen Production from Ethanol
- 2020
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 3:10, s. 10131-10138
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Tidskriftsartikel (refereegranskat)abstract
- Solar-driven splitting of alcohol utilizing photocatalysts is a promising route to obtain H2 and fine chemicals. Ni nanoparticles have shown great potential for light-driven splitting of alcohol, and their size, exposed facets, and electronic properties play key roles in the performance of photocatalysts. Therefore, purposefully modifying Ni is of great importance. In this report, Ni–Ag nanostructures were fabricated in situ on graphitic carbon nitride by a sequential photodeposition method. The solar-driven hydrogen production from ethanol was dramatically enhanced on the Ni–Ag nanostructure-modified graphitic carbon nitride compared with pure Ni nanoparticle-modified graphitic carbon nitride. It was found that the beneficial role of Ag is to disperse and stabilize small Ni nanoparticles and, importantly, expose catalytic sites that are less prone to accumulate ethanol decomposition products (acetate species), as proven by in situ diffuse reflectance infrared Fourier transform spectroscopy.
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| 4. |
- de Jesus Beleno-Saenz, Kelvin, et al.
(författare)
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Non-Invasive Method to Detect Infection with Mycobacterium tuberculosis Complex in Wild Boar by Measurement of Volatile Organic Compounds Obtained from Feces with an Electronic Nose System
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:2
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Tidskriftsartikel (refereegranskat)abstract
- More effective methods to detect bovine tuberculosis, caused by Mycobacterium bovis, in wildlife, is of paramount importance for preventing disease spread to other wild animals, livestock, and human beings. In this study, we analyzed the volatile organic compounds emitted by fecal samples collected from free-ranging wild boar captured in Donana National Park, Spain, with an electronic nose system based on organically-functionalized gold nanoparticles. The animals were separated by the age group for performing the analysis. Adult (>24 months) and sub-adult (12-24 months) animals were anesthetized before sample collection, whereas the juvenile (<12 months) animals were manually restrained while collecting the sample. Good accuracy was obtained for the adult and sub-adult classification models: 100% during the training phase and 88.9% during the testing phase for the adult animals, and 100% during both the training and testing phase for the sub-adult animals, respectively. The results obtained could be important for the further development of a non-invasive and less expensive detection method of bovine tuberculosis in wildlife populations.
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| 5. |
- Dettenrieder, Carina, et al.
(författare)
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Determination of volatile organic compounds in water by attenuated total reflection infrared spectroscopy and diamond-like carbon coated silicon wafers
- 2020
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Ingår i: Chemosensors. - : MDPI. - 2227-9040. ; 8:3, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Volatile organic compounds (VOCs) are one of the most commonly detected contaminants in water. The occurrence is mainly in gasoline and other petroleum-based products, fumigants, paints and plastics. Releases into the environment and the widespread use have an impact on the ecosystem such as humans and animals due to their toxicity, mutagenicity, and carcinogenicity. VOCs may persist in groundwater and may enter drinking water supplies. In this paper, a diamond-like carbon (DLC)-coated silicon waveguide in combination with a polymer film (ethylene/propylene copolymer, E/P-co) for enrichment of analytes was investigated to determine its suitability for ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopic detection of VOCs. The DLC film was fluorine-terminated enhancing the adhesion of the hydrophobic polymer to the waveguide surface. The analytes diffuse into the hydrophobic polymer whereas water is excluded from the emanating evanescent field. Therefore, direct detection in aqueous systems is enabled. Nine VOCs, i.e., ethylbenzene (EB), trichloroethylene (TCE), tetrachloroethylene (TeCE), the xylene isomers (p-xylene, pXYL; m-xylene, mXYL; o-xylene, oXYL), naphthalene (NAPH), toluene (TOL), and benzene (BENZ), were evaluated simultaneously qualitatively and quantitatively showing the potential of DLC coatings revealing high sensitivities in the low ppb to ppm concentration range, i.e., 50 ppb for TeCE. To the best of our knowledge, this is the first time of IR spectroscopic detection of VOCs in aqueous solutions using DLC-coated waveguides in combination with a hydrophobic polymer. By utilizing a DLC-coated waveguide, a versatile sensor for real-time monitoring in harsh environments such as effluents, leaking pipelines, and underground storage tanks is feasible due to response times within a few minutes.
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| 6. |
- Diouf, Alassane, et al.
(författare)
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An electrochemical sensor based on chitosan capped with gold nanoparticles combined with a voltammetric electronic tongue for quantitative aspirin detection in human physiological fluids and tablets
- 2020
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : ELSEVIER. - 0928-4931 .- 1873-0191. ; 110
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Tidskriftsartikel (refereegranskat)abstract
- Inflammatory diseases increase has recently sparked the research interest for drugs diagnostic tools development. At therapeutic doses, acetylsalicylic acid (ASA or aspirin) is widely used for these diseases' treatment. ASA overdoses can however give rise to adverse side effects including ulcers, gastric damage. Hence, development of simple, portable and sensitive methods for ASA detection is desirable. This paper reports aspirin analysis in urine, saliva and pharmaceutical tablet using an electrochemical sensor and a voltammetric electronic tongue (VE-Tongue). The electrochemical sensor was fabricated by self-assembling chitosan capped with gold nanoparticles (Cs + AuNPs) on a screen-printed carbon electrode (SPCE). It exhibits a logarithmic-linear relationship between its response and the ASA concentration in the range between 1 pg/mL and 1 mu g/mL. A low detection limit (0.03 pg/mL), good selectivity against phenol and benzoic acid interference, and successful practical application were demonstrated. Qualitative analysis was performed using the VE-Tongue based unmodified metal electrodes combined with two chemometric approaches to classify urine samples spiked with different aspirin concentrations. Partial least squares (PLS) method provided prediction models obtained from the data of both devices with a regression correlation coefficient R-2 = 0.99. Correspondingly, the SPCE/(Cs + AuNPs) electrochemical sensor and VE-Tongue could be viable tools for biological analysis of drugs.
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| 7. |
- Drozdowska, Katarzyna, et al.
(författare)
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Combined chemoresistive and in situ FTIR spectroscopy study of nanoporous NiO films for light-activated nitrogen dioxide and acetone gas sensing
- 2022
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 353
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Tidskriftsartikel (refereegranskat)abstract
- The chemoresistive sensor response of nanoporous NiO films prepared by advanced gas deposition was investigated by combined resistivity and in situ FTIR spectroscopy, with and without simultaneous light illumination, to detect NO2 and acetone gases. The sensitivity towards NO2 increased dramatically under UV irradiation employing 275 nm light. Improved sensitivity was observed at an elevated temperature of 150 degrees C. In situ FTIR measurements were performed to record the transient gas adsorption/desorption processes. The sustained sensitivity and repeatability for NO2 sensing could be attributed to reversible surface-nitro and nitrate species formation, which are stable on the surface at relative humidity up to 40%. In contrast, acetone sensing results in irreversible decomposition and accumulation of reaction products on the NiO sensor surface, covering the surface and limiting gas sensing. Implications of the study for improved and sustained NiO gas sensor properties in gas mixtures are discussed.
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| 8. |
- Drozdowska, Katarzyna, et al.
(författare)
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Organic Vapor Sensing Mechanisms by Large-Area Graphene Back- Gated Field-Effect Transistors under UV Irradiation
- 2022
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 7:10, s. 3094-3101
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Tidskriftsartikel (refereegranskat)abstract
- The gas sensing properties of graphene back-gated field-effect transistor (GFET) sensors toward acetonitrile, tetrahydrofuran, and chloroform vapors were investigated with the focus on unfolding possible gas detection mechanisms. The FET configuration of the sensor device enabled gate voltage tuning for enhanced measurements of changes in DC electrical characteristics. Electrical measurements were combined with a fluctuation-enhanced sensing methodology and intermittent UV irradiation. Distinctly different features in 1/f noise spectra for the organic gases measured under UV irradiation and in the dark were observed. The most intense response observed for tetrahydrofuran prompted the decomposition of the DC characteristic, revealing the photoconductive and photogating effect occurring in the graphene channel with the dominance of the latter. Our observations shed light on understanding surface processes at the interface between graphene and volatile organic compounds for graphene-based sensors in ambient conditions that yield enhanced sensitivity and selectivity.
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| 9. |
- Fernandes, Daniel Filipe Félix, et al.
(författare)
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Photocatalytic activity of TiO2 deposited by reactive HiPIMS with long target-to-substrate distance
- 2023
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 467
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Tidskriftsartikel (refereegranskat)abstract
- Reactive High Power Impulse Magnetron Sputtering (HiPIMS) of TiO2 thin films was carried out to investigate the influence of ion parameters and the deposition temperature on the film crystallinity and photocatalytic performance. In order to limit unintentional substrate heating, a deposition setup with long target-to-substrate distance was used. Different HiPIMS pulse configurations, deposition temperatures and substrate bias were evaluated. TiO2 films prepared by pulsed dc magnetron sputtering were used as reference. Films deposited at room temperature were all found to be X-ray amorphous, and a minimum temperature of 200 degrees C was needed for film crystallization irrespective of the mode of operation. This is attributed to the relatively long target-to -substrate distance of 180 mm used in this work. The growth of a specific polymorph was shown to be depen-dent on the operation mode, where a high oxygen partial pressure was ideal for anatase formation. The pho-todegradation rates were, as expected, found to be highest for crystalline samples, where single-and mixed-phase films yielded similar rates. Furthermore, the photodegradation rates of HiPIMS films deposited without substrate heating could be enhanced up to 3 times as compared to the corresponding pulsed dc reference film. The ion assistance in HiPIMS is also beneficial at moderate temperatures, here 200 degrees C, where an improved crystallinity as compared to pdcMS, was observed.
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| 10. |
- Hu, Qitao, et al.
(författare)
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Nanotransistor-based gas sensing with record-high sensitivity enabled by electron trapping effect in nanoparticles
- 2024
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Highly sensitive, low-power, and chip-scale H2 gas sensors are of great interest to both academia and industry. Field-effect transistors (FETs) functionalized with Pd nanoparticles (PdNPs) have recently emerged as promising candidates for such H2 sensors. However, their sensitivity is limited by weak capacitive coupling between PdNPs and the FET channel. Herein we report a nanoscale FET gas sensor, where electrons can tunnel between the channel and PdNPs and thus equilibrate them. Gas reaction with PdNPs perturbs the equilibrium, and therefore triggers electron transfer between the channel and PdNPs via trapping or de-trapping with the PdNPs to form a new balance. This direct communication between the gas reaction and the channel enables the most efficient signal transduction. Record-high responses to 1–1000 ppm H2 at room temperature with detection limit in the low ppb regime and ultra-low power consumption of ∼300 nW are demonstrated. The same mechanism could potentially be used for ultrasensitive detection of other gases. Our results present a supersensitive FET gas sensor based on electron trapping effect in nanoparticles.
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