| 1. |
- Arvizu, Miguel A, et al.
(författare)
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Electrochromic WO3 thin films attain unprecedented durability by potentiostatic pretreatment
- 2019
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 7:6, s. 2908-2918
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Tidskriftsartikel (refereegranskat)abstract
- Electrochromic windows and glass facades are able to impart energy efficiency jointly with indoor comfort and convenience. Long-term durability is essential for practical implementation of this technology and has recently attracted broad interest. Here we show that a simple potentiostatic pretreatment of sputterdeposited thin films of amorphous WO3-the most widely studied electrochromic material-can yield unprecedented durability for charge exchange and optical modulation under harsh electrochemical cycling in a Li-ion-conducting electrolyte and effectively evades harmful trapping of Li. The pretreatment consisted of applying a voltage of 6.0 V vs. Li/Li+ for several hours to a film backed by a transparent conducting In2O3: Sn layer. Associated compositional and structural modifications were probed by several techniques, and improved durability was associated with elemental intermixing at the WO3/ITO and ITO/glass boundaries as well as with carbonaceous solid-electrolyte interfacial layers on the WO3 films. Our work provides important new insights into long-term durability of ion-exchange-based devices.
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| 2. |
- Cindemir, Umut, 1986-, et al.
(författare)
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Characterization of nanocrystalline-nanoporous nickel oxide thin films prepared by reactive advanced gas deposition
- 2019
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Ingår i: Materials Chemistry and Physics. - : ELSEVIER SCIENCE SA. - 0254-0584 .- 1879-3312. ; 227, s. 98-104
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Tidskriftsartikel (refereegranskat)abstract
- Nanocrystalline-nanoporous Ni oxide is of much interest for gas sensors and other applications. Reactive advanced gas deposition (AGD) stands out as a particularly promising technique for making thin films of this material owing to the techniques ability to separate between the growth of individual nanoparticles and their subsequent deposition to create a consolidated material on a substrate. Here we report on the characterization of Ni oxide films, made by reactive AGD, by several methods. X-ray diffractometry showed that the films had a face centered cubic NiO structure, and scanning electron microscopy indicated a compact nanoparticulate composition. X-ray photoelectron spectroscopy showed the presence of Ni3+ and demonstrated that these states became less prominent upon heat treatment in air. Extended x-ray absorption fine structure analysis elucidated the local atomic structure; in particular, data on interatomic distances and effects of annealing on local disorder showed that the Ni oxide nanoparticles crystallize upon annealing while maintaining their nanoparticle morphology, which is a crucial feature for reproducible fabrication of Ni oxide thin films for gas sensors. Importantly, several techniques demonstrated that grain growth remained modest for annealing temperatures as high as 400 degrees C for 1700-nm-thick films. The present article is a sequel to an earlier one [U. Cindemir et al., Sensors and Actuators B 242 (2017) 132-139] in which we reported on fluctuation-enhanced and conductometric gas sensing with Ni oxide films prepared by AGD.
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| 4. |
- Geremariam Welearegay, Tesfalem, et al.
(författare)
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Diagnosis of Human Echinococcosis via Exhaled Breath Analysis : A Promise for Rapid Diagnosis of Infectious Diseases Caused by Helminths
- 2019
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 219:1, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- Background: Human echinococcosis is a neglected infectious disease affecting more than 1 million people globally. Its diagnosis is expensive and difficult because of lack of adequate resources in low-resource locations, where most cases occur.Methods: A group of volunteers diagnosed with the 2 main types of echinococcosis and corresponding control groups were recruited from hospitals in Tunisia (32 patients with cystic echinococcosis and 43 controls) and Poland (16 patients with alveolar echinococcosis and 8 controls). Breath samples were collected from all patients and analyzed by gas chromatography coupled to mass spectrometry, and a specifically developed electronic nose system.Results: The chemical analysis revealed statistically different concentrations of 2 compounds in the breath of patients with cystic echinococcosis compared to controls, and statistically different concentrations of 7 compounds in the breath of patients with alveolar echinococcosis compared to controls. The discrimination accuracy achieved by the electronic nose system was 100% for cystic echinococcosis and 92.9% for alveolar echinococcosis, while the discrimination accuracy between these 2 patient groups was 92.1%.Conclusion: Here we advocate a noninvasive, fast, easy-to-operate and nonexpensive diagnostic tool for the diagnosis of human echinococcosis disease through exhaled breath analysis, suitable for early diagnosis and population screening.
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| 5. |
- Geremariam Welearegay, Tesfalem, et al.
(författare)
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Fabrication and characterisation of ligand-functionalised ultrapure monodispersed metal nanoparticle nanoassemblies employing advanced gas deposition technique
- 2018
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Ingår i: Nanotechnology. - : IOP PUBLISHING LTD. - 0957-4484 .- 1361-6528. ; 29:6
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Tidskriftsartikel (refereegranskat)abstract
- Here, we report for the first time the fabrication of ligand-functionalised ultrapure monodispersed metal nanoparticles (Au, Cu, and Pt) from their pure metal precursors using the advanced gas deposition technique. The experimental conditions during nanoparticle formation were adjusted in order to obtain ultrafine isolated nanoparticles on different substrates. The morphology and surface analysis of the as-deposited metal nanoparticles were investigated using scanning electron microscopy, x-ray diffraction and Fourier transform infra-red spectroscopy, which demonstrated the formation of highly ordered pure crystalline nanoparticles with a relatively uniform size distribution of similar to 10 nm (Au), similar to 4 nm (Cu) and similar to 3 nm (Pt), respectively. A broad range of organic ligands containing thiol or amine functional groups were attached to the nanoparticles to form continuous networks of nanoparticle-ligand nanoassemblies, which were characterised by scanning electron microscopy and x-ray photoelectron spectroscopy. The electrical resistance of the functional nanoassemblies deposited in the gap spacing of two microfabricated parallel Au electrodes patterned on silicon substrates ranged between tens of k Omega and tens of M Omega, which is suitable for use in many applications including (bio)chemical sensors, surface-enhanced Raman spectroscopy and molecular electronic rectifiers.
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| 7. |
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| 8. |
- Qu, Hui-Ying, et al.
(författare)
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Electrochemical Rejuvenation of Anodically Coloring Electrochromic Nickel Oxide Thin Films
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; :9, s. 42420-42424
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Tidskriftsartikel (refereegranskat)abstract
- Nickel oxide thin films are of major importance as anodically coloring components in electrochromic smart windows with applications in energy-efficient buildings. However, the optical performance of these films degrades upon extended electrochemical cycling, which has hampered their implementation. Here, we use a potentiostatic treatment to rejuvenate degraded nickel oxide thin films immersed in electrolytes of LiClO4 in propylene carbonate. Time-of-flight elastic recoil detection analysis provided unambiguous evidence that both Li+ ions and chlorine-based ions participate in the rejuvenation process. Our work provides new perspectives for developing ion-exchange-based devices embodying nickel oxide.
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| 9. |
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| 10. |
- Smulko, Janusz, et al.
(författare)
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UV Light-Modulated Fluctuation-Enhanced Gas Sensing by Layers of Graphene Flakes/TiO2 Nanoparticles
- 2020
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Ingår i: Journal of Sensors. - : HINDAWI LTD. - 1687-725X .- 1687-7268. ; 2020
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental results of fluctuation-enhanced gas sensing by low-cost resistive sensors made of a mixture of graphene flakes and TiO(2)nanoparticles. Both components are photocatalytic and activated by UV light. Two UV LEDs of different wavelengths (362 and 394 nm) were applied to modulate the gas sensing of the layers. Resistance noise was recorded at low frequencies, between 8 Hz and 10 kHz. The sensors' response was observed in an ambient atmosphere of synthetic air and toxic NO(2)at selected concentrations (5, 10, and 15 ppm). We observed that flicker noise changed its frequency dependence at different UV light wavelengths, thereby providing additional information about the ambient atmosphere. The power spectral density changed by a few times as a result of UV light irradiation. The sensors were operated at 60 and 120 degrees C, and the effect of UV light on gas sensing was most apparent at low operating temperature. We conclude that UV light activates the gas-sensing layer and improves gas detection at low concentrations of NO2. This result is desirable for the detection of the components of gas mixtures, and the modulated sensor can replace an array of independent resistive sensors which would consume much more energy for heating. We also suggest that a more advanced technology for preparing the gas-sensing layer, by use of spin coating, will produce corresponding layers with thickness of about a few mu m, which is about ten times less than that for the tested samples. The effects induced by the applied UV light, having a penetration depth of only a few mu m, would then be amplified.
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| 11. |
- Sobetkii, A., et al.
(författare)
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Deposition And Characterization Of Thin Films Based On Nanostructured Wo3 As Sensorial Elements For Detection O F H2S
- 2020
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Ingår i: REVISTA ROMANA DE MATERIALE-ROMANIAN JOURNAL OF MATERIALS. - : SERBAN SOLACOLU FOUNDATION. - 1583-3186. ; 50:3, s. 387-394
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Tidskriftsartikel (refereegranskat)abstract
- Thin nanostructured films are the state-of-the-art materials for detection of very low limits of toxic gases. The work presents a comparison between the properties of WO3 thin films obtained by two different deposition techniques: Advanced Gas Deposition (AGD) and DC Reactive Sputtering. Films have been characterized by XRD, SEM and XPS. WO3-based sensors have selective sensitivity in H2S detection at operating temperature of 200 degrees C and relative humidity specific to field applications. The potential interferences with CO2, SO2 and NH3 are negligible, highlighting the application potential of WO3.
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| 12. |
- Welearegay, Tesfalem, et al.
(författare)
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Exhaled air analysis as a potential fast method for early diagnosis of dengue disease
- 2020
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Ingår i: Sensors and actuators. B, Chemical. - Netherlands : Elsevier BV. - 0925-4005 .- 1873-3077. ; 310
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Tidskriftsartikel (refereegranskat)abstract
- Dengue is a neglected tropical disease caused by arbovirus. Every year 390 million persons are infected with dengue, of which 96 million manifest clinically around the world, mainly in the Latin America, South-East Asia and Western Pacific. The disease manifests itself as a flu-like infection that generally is difficult to recognise from a normal flu or other viral infections. The mortality rate is around 20 % for the severe form of dengue, which readily could be decreased to below 1% with early, reliable diagnostic tools. Today there exist however no diagnostic tests for the early and rapid diagnosis of this disease. In this study, we report for the first time the possibility of identification of possible biomarkers associated with dengue disease in the exhaled air, and of the development of a breath test for fast, non-invasive and easy diagnosis of this disease. Further, we demonstrate a new deployable sensor technology based on a chemoresistive metal-ligand nanoassembly tailored for the identified possible biomarkers of dengue disease, which achieved 100 % accuracy for dengue diagnosis on our study group and can be used in both specialist and non-specialist settings. Nevertheless, as the present study was performed on a limited number of patients because of the difficulty to recruit a high number of patients because dengue is a neglected disease, future validation tests on a higher cohort are necessary for corroborating the results obtained in the present study.
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| 13. |
- Welearegay, Tesfalem Geremariam, et al.
(författare)
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Ligand-Capped Ultrapure Metal Nanoparticle Sensors for the Detection of Cutaneous Leishmaniasis Disease in Exhaled Breath
- 2018
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 3:12, s. 2532-2540
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Tidskriftsartikel (refereegranskat)abstract
- Human cutaneous leishmaniasis, although designated as one of the most neglected tropical diseases, remains underestimated due to its misdiagnosis. The diagnosis is mainly based on the microscopic detection of amastigote forms, isolation of the parasite, or the detection of LeishmaniaDNA, in addition to its differential clinical characterization; these tools are not always available in routine daily practice, and they are expensive and time-consuming. Here, we present a simple-to-use, noninvasive approach for human cutaneous leishmaniasis diagnosis, which is based on the analysis of volatile organic compounds in exhaled breath with an array of specifically designed chemical gas sensors. The study was realized on a group of n = 28 volunteers diagnosed with human cutaneous leishmaniasis and a group of n = 32 healthy controls, recruited in various sites from Tunisia, an endemic country of the disease. The classification success rate of human cutaneous leishmaniasis patients achieved by our sensors test was 98.2% accuracy, 96.4% sensitivity, and 100% specificity. Remarkably, one of the sensors, based on CuNPs functionalized with 2-mercaptobenzoxazole, yielded 100% accuracy, 100% sensitivity, and 100% specificity for human cutaneous leishmaniasis discrimination. While AuNPs have been the most extensively used in metal nanoparticle–ligand sensing films for breath sensing, our results demonstrate that chemical sensors based on ligand-capped CuNPs also hold great potential for breath volatile organic compounds detection. Additionally, the chemical analysis of the breath samples with gas chromatography coupled to mass spectrometry identified nine putative breath biomarkers for human cutaneous leishmaniasis.
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