| 1. |
- Dawi, E. A., et al.
(författare)
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Ag/AgCl Decorated Ionic Liquid@Tantalum Pentoxide Nanostructures: Fabrication, Photocatalytic Activity, and Cytotoxicity Effects Against Human Brain Tumor Cells
- 2023
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Ingår i: JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS. - : SPRINGER. - 1574-1443. ; 33, s. 2647-2660
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Tidskriftsartikel (refereegranskat)abstract
- Environmental contaminants have become a major concern for human beings due to their adverse effects on drinking water quality. Heterogeneous photocatalysis has been extensively investigated as a potential strategy to minimize the consequences of as-related processes. Using a room-temperature ionic liquid-mediated co-precipitation method, Ag@AgCl nanoparticles were loaded onto tantalum pentoxide to make a plasmonic photocatalyst to remove Congo Red dye. The physicochemical properties of the photocatalysts were characterized by X-ray diffraction powder (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Diffuse Reflectance Spectroscopy (DRS), Fourier-transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), photoluminescence (PL), and nitrogen adsorption-desorption isotherms. The results indicate that 96% of the dye was degraded within 20 min with a rate constant of 0.14 min(-1). The key radicals involved in the photocatalysis, recognized as O-2(center dot-) species, were identified by electron spin resonance (ESR) in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), as the spin trapping agent. Our findings and quenching experiments elucidates the mechanism of the charge carrier migration. The cytotoxicity activity of the nanostructures was also examined against human brain glioblastoma tumor cells for the first time. A precise analysis of the cell death pathway was conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and caspase activity assays in combination with fluorescence microscopy images. The prepared nanomaterials were found to be promising candidates for treating the organic pollutants and biomedical waste effluents from academic and industrial activities.
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| 2. |
- Mustafa, Elfatih Mohammed, et al.
(författare)
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Efficient CuO/Ag2WO4 photoelectrodes for photoelectrochemical water splitting using solar visible radiation
- 2023
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Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 13:17, s. 11297-11310
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Tidskriftsartikel (refereegranskat)abstract
- Water splitting energy production relies heavily on the development of high-performance photoelectrochemical cells (PECs). Among the most highly regarded semiconductor materials, cupric oxide (CuO) is an excellent photocathode material. Pristine CuO does not perform well as a photocathode due to its tendency to recombine electrons and holes rapidly. Photocathodes with high efficiency can be produced by developing CuO-based composite systems. The aim of our research is to develop an Ag2WO4/CuO composite by incorporating silver tungstate (Ag2WO4) nanoparticles onto hydrothermally grown CuO nanoleaves (NLs) by successive ionic layer adsorption and reaction (SILAR). To prepare CuO/Ag2WO4 composites, SILAR was used in conjunction with different Ag2WO4 nanoparticle deposition cycles. Physicochemical characterization reveals well-defined nanoleaves morphologies with tailored surface compositions. Composite CuO/Ag2WO4 crystal structures are governed by the monoclinic phase of CuO and the hexagonal phase of Ag2WO4. It has been demonstrated that the CuO/Ag2WO4 composite has outstanding performance in the PEC water splitting process when used with five cycles. In the CuO/Ag2WO4 photocathode, water splitting activity is observed at low overpotential and high photocurrent density, indicating that the reaction takes place at low energy barriers. Several factors contribute to PEC performance in composites. These factors include the high density of surface active sites, the high charge separation rate, the presence of favourable surface defects, and the synergy of CuO and Ag2WO4 photoreaction. By using SILAR, silver tungstate can be deposited onto semiconducting materials with strong visible absorption, enabling the development of energy-efficient photocathodes.
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| 3. |
- Savoyant, A., et al.
(författare)
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Light-induced high-spin state in ZnO nanoparticles
- 2020
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Ingår i: Nanotechnology. - : IOP PUBLISHING LTD. - 0957-4484 .- 1361-6528. ; 31:9
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Tidskriftsartikel (refereegranskat)abstract
- The effects of white-light irradiation on similar to 15.nm diameter ZnO nanoparticles are investigated by means of electron paramagnetic resonance, near liquid-nitrogen and liquid-helium temperatures. Under dark conditions, usual core- and surface-defects are detected, respectively, at g = 1.960 and g = 2.003. Under white-light illumination, the core-defect signal intensity is strongly increased, which is to be correlated to the light-induced conductivitys augmentation. Beside, a four-lines structure appears, with the same gravity center as that of the surface defects. Simulations and intensity power-dependence measurements show that this four-line-structure is very likely to arise from a localized high spin S = 2, induced by light irradiation, and subjected to a weak axial anisotropy. At 85K, this high-spin state can last several hours after the light-irradiation removal, probably due to highly spin-forbidden recombination process. The possible excited resonant complexes at the origin of this signal are discussed. Other light-induced S = 1/2-like centers are detected as well, which depend on the nanoparticles growth conditions.
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| 4. |
- Angizi, S., et al.
(författare)
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Review-Towards the Two-Dimensional Hexagonal Boron Nitride (2D h-BN) Electrochemical Sensing Platforms
- 2020
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 167:12
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical sensing performance of two-dimensional hexagonal boron nitride (2D h-BN) has traditionally been suppressed by their intrinsic electrical insulation and deficient electron transportation mechanism. However, the excellent electrocatalytic activity, high specific surface area, N- and B-active edges, structural defects, adjustable band gap through interaction with other nanomaterials, and chemical functionalization, makes 2D h-BN ideal for many sensing applications. Therefore, finding a pathway to modulate the electronic properties of 2D h-BN while the intrinsic characteristics are well preserved, will evolve a new generation of highly sensitive and selective electrochemical (bio)sensors. That is why extensive research has recently focused on the challenge to functionalize 2D h-BN by controlling the surface chemical reactions with external species, particularly metal nanoparticles. This review summarizes the most recent progress in the application of 2D h-BN nanosheets in electrochemical (bio)sensing. We will explore the fabrication techniques of 2D h-BN for electrochemical applications followed by thorough discussion on their advantages, shortcomings, and promising possibilities as (bio)sensing platforms in near future.
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| 5. |
- Razmi, Nasrin, et al.
(författare)
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Monitoring the effect of pH on the growth of pathogenic bacteria using electrical impedance spectroscopy
- 2023
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Ingår i: Results in Engineering (RINENG). - : ELSEVIER. - 2590-1230. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- pH value is a significant environmental factor controlling the bacterial growth, activity and affecting their metabolic properties. In the present study, the effect of the different pH values (5, 6, 7, 8, and 9) of the cultivation medium on the growth rate of Escherichia coli ATCC 8739, Bacillus cereus ATCC 10876 and Pseudomonas aeruginosa 134,909/2 were studied. Plate count method and spectrophotometric measurement of optical density of the cultivation broth were used to assess growth of the pathogenic bacteria. Moreover, impedance spectroscopy measurement was applied to monitor the impedance change caused by the bacterial growth and activity at different pH values. Although the results showed that the initial pH did not completely inhibit the growth of the bacteria, the bacterial growth varied with the pH change showing the interference of pH with cell metabolism. Based on the results, the optical density of the cultivation broth measured spectrophotometrically for E. coli and B. cereus has shown good correlation with cell number determined by the plate count method in each phase of bacterial cultivation. Moreover, the results indicated that for E. coli and B. cereus the impedance value of the bacteria and the medium decreased from the beginning of the experiment till its end after 96 h from the start The impedance value during the first 24 h increased for P. aeruginosa, and then was decreasing until the end of the experiment. Nevertheless, the change in the resistance of the bacteria and the medium was proportionate to the change in cell number. For E. coli and B. cereus the resistance was decreasing with the growth of the bacteria. The linear dependency between the impedance and cell number was observed at low frequencies around 10-100 Hz. For P. aeruginosa, the resistance was increasing during the first 24 h and was decreasing afterwards. Furthermore, the resistance for P. aeruginosa was decreasing with the increase in cell number. Nonetheless, the impedance of the medium with P. aeruginosa was in linear dependency on the logarithm of cell number with the best R2 at high frequencies (0.1-1 MHz).
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| 6. |
- Rosa, Eduardo, et al.
(författare)
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Cognitive performance, fatigue, emotional, and physiological strains in simulated long-duration flight missions
- 2022
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Ingår i: Military Psychology. - : Informa UK Limited. - 0899-5605 .- 1532-7876. ; 34:2, s. 224-236
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Tidskriftsartikel (refereegranskat)abstract
- Pilots in long-duration flight missions in single-seat aircraft may be affected by fatigue. This study determined associations between cognitive performance, emotions and physiological activation and deactivation–measured by heart rate variability (HRV)–in a simulated 11-h flight mission in the 39 Gripen aircraft. Twelve participants volunteered for the study. Perceived fatigue was measured by the Samn-Perelli Fatigue Index (SPFI). Cognitive performance was measured by non-executive and executive tasks. Emotions were assessed by the Circumplex Affect Space instrument. HRV was considered in relation to the cognitive tasks in four time points–Hours 3, 5, 7, 9–and their associations with emotional ratings. Results indicated a decrease in performance in the non-executive task after approximately 7 h. This result was correlated with self-reported measures of fatigue. HRV, assessed by indices of parasympathetic modulation, remained unchanged for both non-executive and executive tasks over time (p >.05 for all). Significant correlations were observed between emotions and HRV; with increased boredom, increased passiveness, decreased stimulation, and decreased activeness, HRV indicators increased (p <.05). This suggests that a low self-regulatory effort for maintaining performance in these conditions was prevalent and that pilots could adapt to some degree to the demands and fatigue of long-duration missions.
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