| 1. |
- Bandara, T M W J, 1968, et al.
(författare)
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Diatom frustules enhancing the efficiency of gel polymer electrolyte based dye-sensitized solar cells with multilayer photoelectrodes
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:1, s. 199-209
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of nanostructures that improve light scattering and dye adsorption has been suggested for dye-sensitized solar cells (DSSCs), but the manufacture of photonic and nanostructured materials with the desired properties is not an easy task. In nature, however, the process of light-harvesting for photosynthesis has, in some cases, evolved structures with remarkable wavelength-sensitive light-trapping properties. The present work is focused on enhancing the efficiency of quasi solid-state DSSCs by capitalizing on the light trapping properties of diatom frustules since they provide complex 3-dimensional structures for scattering and trapping light. This study reports a promising approach to prepare TiO2 nanocrystal (14 nm) based photo-electrodes by utilizing the waveguiding and photon localization effects of nanostructured diatom frustules for enhancing light harvesting without deteriorating the electron conduction. Single and double-layered photo-electrodes were prepared with different frustule/nanocrystal combinations and conformations on transparent conductive oxide substrates. This study clearly reports impressive efficiency and short circuit current density enhancements of about 35% and 39%, respectively, due to the incorporation of diatom frustules extracted from a ubiquitous species. The SEM images obtained in this work reveal that the produced thin films had a remarkable surface coverage of evenly distributed frustules within the TiO2 nanoparticle layer. To the best of our knowledge, this study reports the first quasi solid-state DSSC based on a photo-electrode with incorporated bio-formed nanostructures.
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| 2. |
- Das, Nandan, 1983-, et al.
(författare)
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Nanoscale structure detection and monitoring of tumour growth with optical coherence tomography
- 2020
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Ingår i: Nanoscale Advances. - : ROYAL SOC CHEMISTRY. - 2516-0230. ; 2:7, s. 2853-2858
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Tidskriftsartikel (refereegranskat)abstract
- Approximately 90% of cancers originate in epithelial tissues leading to epithelial thickening, but the ultrastructural changes and underlying architecture are less well known. Depth resolved label free visualization of nanoscale tissue morphology is required to reveal the extent and distribution of ultrastructural changes in underlying tissue, but is difficult to achieve with existing imaging modalities. We developed a nanosensitive optical coherence tomography (nsOCT) approach to provide suchimaging based on dominant axial structure with a few nanometre detection accuracy. nsOCT maps the distribution of axial structural sizes an order of magnitude smaller than the axial resolution of the system. We validated nsOCT methodology by detecting synthetic axial structure via numerical simulations. Subsequently, we validated the nsOCT technique experimentally by detecting known structures from a commercially fabricated sample. nsOCT reveals scaling with different depth of dominant submicronstructural changes associated with carcinoma which may inform the origins of the disease, its progression and improve diagnosis.
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| 3. |
- Dom, Rekha, et al.
(författare)
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A solar-responsive zinc oxide photoanode for solar-photon-harvester photoelectrochemical (PEC) cells
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:8, s. 3350-3357
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Tidskriftsartikel (refereegranskat)abstract
- A highly efficient, nanostructured, solar-responsive zinc-oxide (SRZO) photoanode has been achieved by utilization of a versatile solution precursor plasma spray (SPPS) deposition technique. For the first time, it is demonstrated that a front-illumination type SRZO photo-anode fabricated with a ZnO/stainless steel (SS-304) configuration can generate an enhanced photo-electrochemical (PEC) current of 390 mA cm(-2), under solar radiation from a solar simulator with an AM1.5 global filter (similar to 1 sun). The SRZO electrode displayed a solar-to-hydrogen (STH) conversion efficiency of 2.32% when investigated for H-2 evolution in a PEC cell. These electrodes exhibited a maximum peak efficiency of 86% using 320 nm photons during incident photon-to-current conversion efficiency measurement. Interestingly, the film lattice of SRZO showed a significant red-shift of 0.37 eV in the ZnO band gap thereby providing solar photon absorptivity to SRZO. Further, an enhanced charge transport property by virtue of increased donor density (similar to 4.11 x 10(17) cm(-3)) has been observed, which is higher by an order of magnitude than that of its bulk counterpart. Efficient optical absorption of solar photons and higher donor-density of SRZO have been thus attributed to its superior PEC performance.
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| 4. |
- Feijoo, Pedro C., et al.
(författare)
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Does carrier velocity saturation help to enhance fmax in graphene field-effect transistors?
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:9, s. 4179-4186
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Tidskriftsartikel (refereegranskat)abstract
- It has been argued that current saturation in graphene field-effect transistors (GFETs) is needed to get optimal maximum oscillation frequency (f(max)). This paper investigates whether velocity saturation can help to get better current saturation and if that correlates with enhancedf(max). We have fabricated 500 nm GFETs with high extrinsicf(max)(37 GHz), and later simulated with a drift-diffusion model augmented with the relevant factors that influence carrier velocity, namely: short-channel electrostatics, saturation velocity effect, graphene/dielectric interface traps, and self-heating effects. Crucially, the model provides microscopic details of channel parameters such as carrier concentration, drift and saturation velocities, allowing us to correlate the observed macroscopic behavior with the local magnitudes. When biasing the GFET so all carriers in the channel are of the same sign resulting in highly concentrated unipolar channel, we find that the larger the drain bias is, both closer the carrier velocity to its saturation value and the higher thef(max)are. However, the highestf(max)can be achieved at biases where there exists a depletion of carriers near source or drain. In such a situation, the highestf(max)is not found in the velocity saturation regime, but where carrier velocity is far below its saturated value and the contribution of the diffusion mechanism to the current is comparable to the drift mechanism. The position and magnitude of the highestf(max)depend on the carrier concentration and total velocity, which are interdependent and are also affected by the self-heating. Importantly, this effect was found to severely limit radio-frequency performance, reducing the highestf(max)from similar to 60 to similar to 40 GHz.
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| 5. |
- Gliga, Anda R., et al.
(författare)
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Silver nanoparticles modulate lipopolysaccharide-triggered Toll-like receptor signaling in immune-competent human cell lines
- 2020
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Ingår i: Nanoscale Advances. - : ROYAL SOC CHEMISTRY. - 2516-0230. ; 2:2, s. 648-658
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Tidskriftsartikel (refereegranskat)abstract
- Silver (Ag) nanoparticles are commonly used in consumer products due to their antimicrobial properties. Here we studied the impact of Ag nanoparticles on immune responses by using cell lines of monocyte/macrophage and lung epithelial cell origin, respectively. Short-term experiments (24 h) showed that Ag nanoparticles reduced the lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines in THP-1 cells under serum-free conditions. ICP-MS analysis revealed that cellular uptake of Ag was higher under these conditions. Long-term exposure (up to 6 weeks) of BEAS-2B cells to Ag nanoparticles also suppressed pro-inflammatory cytokine production following a brief challenge with LPS. Experiments using reporter cells revealed that Ag nanoparticles as well as AgNO3 inhibited LPS-triggered Toll-like receptor (TLR) signaling. Furthermore, RNA-sequencing of BEAS-2B cells indicated that Ag nanoparticles affected TLR signaling pathways. In conclusion, Ag nanoparticles reduced the secretion of pro-inflammatory cytokines in response to LPS, likely as a result of the release of silver ions leading to an interference with TLR signaling. This could have implications for the use of Ag nanoparticles as antibacterial agents. Further in vivo studies are warranted to study this.
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| 6. |
- Nair, Akhil S., et al.
(författare)
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Unraveling the single-atom electrocatalytic activity of transition metal-doped phosphorene
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:6, s. 2410-2421
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Tidskriftsartikel (refereegranskat)abstract
- The development of single-atom catalysts (SACs) for chemical reactions of vital importance in the renewable energy sector has emerged as an urgent priority. In this perspective, transition metal-based SACs with monolayer phosphorous (phosphorene) as the supporting material are scrutinized for their electrocatalytic activity towards the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) from first-principle calculations. The detailed screening study has confirmed a breaking of the scaling relationship between the ORR/OER intermediates, resulting in various activity trends across the transition metal series. Groups 9 and 10 transition metal-based SACs are identified as potential catalyst candidates with the platinum single atom offering bifunctional activity for OER and HER with diminished overpotentials. Ambient condition stability analysis of SACs confirmed a different extent of interaction towards oxygen and water compared to pristine phosphorene, suggesting room for improving the stability of phosphoreneviachemical functionalization.
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| 7. |
- Panda, Pritam Kumar, PhD Student, 1991-, et al.
(författare)
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Progress in supercapacitors : Roles of two dimensional nanotubular materials
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 2:1, s. 70-108
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Tidskriftsartikel (refereegranskat)abstract
- Overcoming the global energy crisis due to vast economic expansion with the advent of human reliance on energy-consuming labor-saving devices necessitates the demand for next-generation technologies in the form of cleaner energy storage devices. The technology accelerates with the pace of developing energy storage devices to meet the requirements wherever an unanticipated burst of power is indeed needed in a very short time. Supercapacitors are predicted to be future power vehicles because they promise faster charging times and do not rely on rare elements such as lithium. At the same time, they are key nanoscale device elements for high-frequency noise filtering with the capability of storing and releasing energy by electrostatic interactions between the ions in the electrolyte and the charge accumulated at the active electrode during the charge/discharge process. There have been several developments to increase the functionality of electrodes or finding a new electrolyte for higher energy density, but this field is still open to witness the developments in reliable materials-based energy technologies. Nanoscale materials have emerged as promising candidates for the electrode choice, especially in 2D sheet and folded tubular network forms. Due to their unique hierarchical architecture, excellent electrical and mechanical properties, and high specific surface area, nanotubular networks have been widely investigated as efficient electrode materials in supercapacitors, while maintaining their inherent characteristics of high power and long cycling life. In this review, we briefly present the evolution, classification, functionality, and application of supercapacitors from the viewpoint of nanostructured materials to apprehend the mechanism and construction of advanced supercapacitors for next-generation storage devices. This journal is
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| 8. |
- Sanchez-Fernandez, Adrian, et al.
(författare)
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An integrative toolbox to unlock the structure and dynamics of protein-surfactant complexes
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:9, s. 4011-4023
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Tidskriftsartikel (refereegranskat)abstract
- The interactions between protein and surfactants play an important role in the stability and performance of formulated products. Due to the high complexity of such interactions, multi-technique approaches are required to study these systems. Here, an integrative approach is used to investigate the various interactions in a model system composed of human growth hormone and sodium dodecyl sulfate. Contrast variation small-angle neutron scattering was used to obtain information on the structure of the protein, surfactant aggregates and surfactant-protein complexes. 1H and 1H-13C HSQC nuclear magnetic resonance spectroscopy was employed to probe the local structure and dynamics of specific amino acids upon surfactant addition. Through the combination of these advanced methods with fluorescence spectroscopy, circular dichroism and isothermal titration calorimetry, it was possible to identify the interaction mechanisms between the surfactant and the protein in the pre- and post-micellar regimes, and interconnect the results from different techniques. As such, the protein was revealed to evolve from a partially unfolded conformation at low SDS concentration to a molten globule at intermediate concentrations, where the protein conformation and local dynamics of hydrophobic amino acids are partially affected compared to the native state. At higher surfactant concentrations the local structure of the protein appears disrupted, and a decorated micelle structure is observed, where the protein is wrapped around a surfactant assembly. Importantly, this integrative approach allows for the identification of the characteristic fingerprints of complex transitions as seen by each technique, and establishes a methodology for an in-detail study of surfactant-protein systems. This journal is
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| 9. |
- Sayed, F., et al.
(författare)
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Symbiotic, low-temperature, and scalable synthesis of bi-magnetic complex oxide nanocomposites
- 2020
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Ingår i: Nanoscale Advances. - : ROYAL SOC CHEMISTRY. - 2516-0230. ; 2:2, s. 851-859
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Tidskriftsartikel (refereegranskat)abstract
- Functional oxide nanocomposites, where the individual components belong to the family of strongly correlated electron oxides, are an important class of materials, with potential applications in several areas such as spintronics and energy devices. For these materials to be technologically relevant, it is essential to design low-cost and scalable synthesis techniques. In this work, we report a low-temperature and scalable synthesis of prototypical bi-magnetic LaFeO3-CoFe2O4 nanocomposites using a unique sol-based synthesis route, where both the phases of the nanocomposite are formed during the same time. In this bottom-up approach, the heat of formation of one phase (CoFe2O4) allows the crystallization of the second phase (LaFeO3), and completely eliminates the need for conventional high-temperature annealing. A symbiotic effect is observed, as the second phase reduces grain growth of the first phase, thus yielding samples with lower particle sizes. Through thermogravimetric, structural, and morphological studies, we have confirmed the reaction mechanism. The magnetic properties of the bi-magnetic nanocomposites are studied, and reveal a distinct effect of the synthesis conditions on the coercivity of the particles. Our work presents a basic concept of significantly reducing the synthesis temperature of bi-phasic nanocomposites (and thus also the synthesis cost) by using one phase as nucleation sites for the second one, as well as using the heat of formation of one phase to crystallize the other.
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| 10. |
- Serrano, Ismael G., et al.
(författare)
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Flexible transparent graphene laminates via direct lamination of graphene onto polyethylene naphthalate substrates
- 2020
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:8, s. 3156-3163
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Tidskriftsartikel (refereegranskat)abstract
- Graphene, with its excellent electrical, mechanical, and optical properties, has emerged as an exceptional material for flexible and transparent nanoelectronics. Such versatility makes it compelling to find new pathways to lay graphene sheets onto smooth, flexible substrates to create large-scale flexible transparent graphene conductors. Here, we report the realization of flexible transparent graphene laminates by direct adhesion of chemical vapor deposition (CVD) graphene on a polyethylene naphthalate (PEN) substrate, which is an emerging standard for flexible electronics. By systematically optimizing the conditions of a hot-press technique, we have identified that applying optimum temperature and pressure can make graphene directly adhere to flexible PEN substrates without any intermediate layer. The resultant flexible graphene films are transparent, have a standard sheet resistance of 1 k Omega with high bending resilience, and high optical transmittance of 85%. Our direct hot-press method is achieved below the glass transition temperature of the PEN substrate. Furthermore, we demonstrate press-assisted embossing for patterned transfer of graphene, and hence it can serve as a reliable new means for creating universal, transparent conducting patterned films for designing flexible nanoelectronic and optoelectronic components.
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