428 research outputs found
Reanalysis of data from Yu and Stellacci [42].
No full text<p>Panels a, c and f reproduce images from Yu and Stellacci (2012) Response to stripy nanoparticles revisited. Small 8: 3720–3726 (DOI: 10.1002/smll.201202322) - reproduced by permission of John Wiley & Sons. (a) Image as presented in Yu and Stellacci (b) A 205 × 205 pixel section of the raw data which has been processed with second order background subtraction, the colour range reduced to just 40% of the original range, and the number of pixels interpolated to best match the image shown in (a); (c) Enlargement of region highlighted by a blue square in (a); (d) Zoom of a section of the image shown in (b) taken after interpolation and colour saturation; (e) Retrace image acquired simultaneously with (d); (f) Image shown in (c) but with the stripes identified by Yu and Stellacci highlighted using dashed lines; (g) Uninterpolated zoom of the raw data showing the true pixelation. (h) Retrace image acquired simultaneously with (g). The “stripes” in (f) not only arise from a very small number of fortuitously aligned pixels, but they are not present in the retrace images shown in (e) and (h).</p
Arithmetic addition of images from Yu and Stellacci [42].
No full text<p>(a)-(j) Images of the same set of nanoparticles taken from each of the five trace and five retrace images provided by Yu and Stellacci. (a,c,e,g,i) are the trace images, while (b,d,f,h,j), respectively, are the corresponding retrace images. (k) Arithmetic addition of all 10 images. Note that the particles in the summed image appear entirely smooth, indicating that the features designated as stripes by Yu and Stellacci arise from noise and not real topographic structure on the nanoparticles. All images are 20 nm wide.</p
A study of the surface plasmon resonance of silver nanoparticles by the discrete dipole approximation method: effect of shape, size, structure and assembly
No full textThe surface plasmon resonance (SPR) of silver nanoparticles (AgNPs) was studied with the discrete dipole approximation considering different shapes, sizes, dielectric environments, and supraparticles assemblies. In particular, we focused our simulations on AgNPs with sizes below 10 nm, where the correction of silver dielectric constant for intrinsic size effects is necessary. We found that AgNPs shape and assembly can induce distinctive features in the extinction spectra and that SPR is more intense when AgNPs have discoid or flat shapes and are embedded in a dielectric shell with high refractive index. However, the SPR loses much of its distinctive features when size effects and stabilizing molecules induce significant broadening of the extinction bands that is often observed in the case of thiolated AgNPs smaller than about 5 nm. These results are useful indications for in situ characterization and monitoring of AgNPs synthesis and for the engineering of AgNPs with new plasmonic properties
Direct mapping of the solid-liquid adhesion energy with subnanometre resolution.
No full textSolid-liquid interfaces play a fundamental role in surface electrochemistry, catalysis, wetting, self-assembly and biomolecular functions. The interfacial energy determines many of the properties of such interfaces, including the arrangement of the liquid molecules at the surface of the solid. Diffraction techniques are often used to investigate the structure of solid-liquid interfaces, but measurements of irregular or inhomogeneous interfaces remain challenging. Here, we report atomic- and molecular-resolution images of various organic and inorganic samples in liquids, obtained with a commercial atomic force microscope operated dynamically with small-amplitude modulation. This approach uses the structured liquid layers close to the solid to enhance lateral resolution. We propose a model to explain the mechanism dominating the image formation, and show that the energy dissipated during this process is related to the interfacial energy through a readily achievable calibration curve. Our topographic images and interfacial energy maps could provide insights into important interfaces
Health risk assessment of air emissions from a municipal solid waste incineration plant – a case study
No full textA health risk assessment of long-term emissions of carcinogenic and non-carcinogenic air pollutants has been carried out for the municipal solid waste incinerator (MSWI) of the city of Taranto, Italy. Ground level air concentrations and soil deposition of carcinogenic (Polychlorinated Dibenzo-p-Dioxins/Furans and Cd) and non-carcinogenic (Pb and Hg) pollutants have been estimated using a well documented atmospheric dispersion model. Health risk values for air inhalation, dermal contact, soil and food ingestion have been calculated based on a combination of these concentrations and a matrix of environmental exposure factors. Exposure of the surrounding population has been addressed for different release scenarios based on four pollutants, four exposure pathways and two receptor groups (children and adults). Spatial risk distribution and cancer excess cases projected from plant emissions have been compared with background mortality records. Estimated results based on the MSWI emissions show: (1) individual risks well below maximum acceptable levels, (2) very small incremental cancer risk compared with background level
From a photochromic diarylethene monomer to a dopable photochromic polymer: optical properties
No full textQuasi- periodic distribution of plasmon modes in two -dimensional Fibonacci arrays of metal nanoparticles
No full textThe use of a nutrient quality score is effective to assess the overall nutritional value of three brassica microgreens
No full textMicrogreens have immense potential for improving dietary patterns, but little information is available regarding their overall nutritional value. We evaluated the nutritional traits of three hydroponically grown Brassica microgreens by using a Nutrient Quality Score. Micro cauliflower, micro broccoli and micro broccoli raab were grown using nutrient solutions with three different NH4:NO3 molar ratios (5:95, 15:85, and 25:75). Protein, dietary fiber, β-carotene, α-tocopherol and mineral elements (Ca, K, Mg, Fe, Zn, Cu, Mn, and Na) were analyzed. We developed the Nutrient Quality Score (NQS 11.1) on the basis of 11 desirable nutrients and 1 nutrient (sodium) to be limited. All Brassica microgreens are an excellent source of Vitamins A and E (more than 20% of the daily reference value-DRV), as well as a good source of calcium and manganese (10-19% of the DRV). Micro cauliflower showed a NQS 11.1 at 47% higher than micro broccoli raab and micro broccoli. Using NH4:NO3 25:75 molar ratio, the average score was 27% higher than other molar ratios. In all cases, the microgreens in the present study showed a higher NQS 11.1 than their mature counterpart (on the basis of data from the United States Department of Agriculture), highlighting that the score of micro cauliflower was about six-fold higher than mature cauliflower. In conclusion, the NQS 11.1 was useful for assessing the overall nutritional quality of the three Brassica microgreens, instead of simply quantifying nutrient content, in order to compare a single nutrient among different genotypes. Furthermore, the results highlight that the micro broccoli raab, micro broccoli and micro cauliflower in this study can be considered nutrient-rich vegetables that are able to improve dietary patterns more effectively than their mature counterparts
Order/Disorder Dynamics in a Dodecanethiol-Capped Gold Nanoparticles Supracrystal by Small-Angle Ultrafast Electron Diffraction
No full textThe design and the characterization of functionalized gold nanoparticles supracrystals require atomically resolved information on both the metallic core and the external organic ligand shell. At present, there is no known approach to characterize simultaneously the static local order of the ligands and of the nanoparticles, nor their dynamical evolution. In this work, we apply femtosecond small-angle electron diffraction combined with angular cross-correlation analysis, to retrieve the local arrangement from nanometer to interatomic scales in glassy aggregates. With this technique we study a two-dimensional distribution of functionalized gold nanoparticles deposited on amorphous carbon. We show that the dodecanethiol ligand chains, coating the gold cores, order in a preferential orientation on the nanoparticle surface and throughout the supracrystal. Furthermore, we retrieve the dynamics of the supracrystal upon excitation with light and show that the positional disorder is induced by light pulses, while its overall homogeneity is surprisingly found to transiently increase. This new technique will enable the systematic investigation of the static and dynamical structural properties of nanoassembled materials containing light elements, relevant for several applications including signal processing and biology.LUMESSUNMI
Local photo-mechanical stiffness revealed in gold nanoparticles supracrystals by ultrafast small-angle electron diffraction
No full textWe demonstrate that highly ordered two-dimensional crystals of ligand-capped gold nanoparticles display a local photo-mechanical stiffness as high as that of solids such as graphite. In out-of-equilibrium electron diffraction experiments, a strong temperature jump is induced in a thin film with a femtosecond laser pulse. The initial electronic excitation transfers energy to the underlying structural degrees of freedom, with a rate generally proportional to the stiffness of the material. Using femtosecond small-angle electron diffraction, we observe the temporal evolution of the diffraction feature associated with the nearest-neighbor nanoparticle distance. The Debye-Waller decay for the octanethiol-capped nanoparticle supracrystal, in particular, is found to be unexpectedly fast, almost as fast as the stiffest solid known and observed by the same technique, i.e., graphite. Our observations unravel that local stiffness in a dense supramolecular assembly can be created by van der Waals interactions up to a level comparable to crystalline systems characterized by covalent bonding
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