This work is devoted to magnesium oxide (MgO) nanoparticles (NPs) for their use as additives for bone implants. Extracts from four different widely used plants, including Aloe vera, Echeveria elegans, Sansevieria trifasciata, and Sedum morganianum, were evaluated for their ability to facilitate the “green synthesis” of MgO nanoparticles. The thermal stability and decomposition behavior of the MgONPs were analyzed by thermogravimetric analysis (TGA). Structure characterization was performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), and Raman scattering spectroscopy (RS). Morphology was studied by scanning electron microscopy (SEM). The photocatalytic activity of MgO nanoparticles was investigated based on the degradation of methyl orange (MeO) using UV-Vis spectroscopy. Surface-enhanced Raman scattering spectroscopy (SERS) was used to monitor the adsorption of L-phenylalanine (L-Phe) on the surface of MgONPs. The calculated enhancement factor (EF) is up to 102 orders of magnitude for MgO. This is the first work showing the SERS spectra of a chemical compound immobilized on the surface of MgO nanoparticles.
In this work, we review the single-adsorbate time-dependent continuum model for focused electron beam-induced deposition (FEBID). The differential equation for the adsorption rate will be expressed by dimensionless parameters describing the contributions of adsorption, desorption, dissociation, and the surface diffusion of the precursor adsorbates. The contributions are individually presented in order to elucidate their influence during variations in the electron beam exposure time. The findings are condensed into three new scaling laws for pulsed exposure FEBID (or FEB-induced etching) relating the lateral resolution of deposits or etch pits to surface diffusion and electron beam exposure dwell time for a given adsorbate depletion state.
Laser‐Induced Graphene (LIG) is a 3D, conductive, porous material with a high surface area, produced by laser irradiation of synthetic polymers with high thermal stability. Recently, the focus has shifted toward sustainable bioderived and biodegradable precursors, such as lignocellulosic materials. Despite starch being an abundant and cost‐effective biopolymer, direct laser scribing on starch‐derived precursors has not yet been explored. This study demonstrates that corn starch bioplastic (SP) can be converted into LIG through iron‐catalyzed laser‐induced pyrolysis, using Fe(NO₃)₃ as an additive. The impact of iron additive concentration on LIG formation and on its properties is investigated, with only certain concentrations yielding reliable and reproducible results. The investigation of LIG's crystal structure reveals magnetic and non‐magnetic iron phases: γ‐Fe₂O₃, Fe₃C, and Fe(C). The LIG nanocomposite exhibits soft magnetic properties, with a coercive field of Hc ≈ 200 Oe and a saturation magnetization of Ms ≈ 67 emu g⁻¹. The SP substrate degrades almost entirely in soil within 12 days and is unaffected by the addition of Fe(NO₃)₃, allowing for material compostability in line with circular economy principles. Consequently, SP stands out as a promising “green” precursor for magnetic LIG, paving the way for sustainable applications in environmental remediation.
In this paper, the conformational changes of tryptophan (Trp) on the corroded 316 L stainless steel (SS) surface obtained under controlled simulated inflammatory conditions have been studied by Raman (RS) and Fourier-transform infrared (FT-IR) spectroscopy methods. The corrosion behavior and protective efficiency of the investigated samples were performed using the potentiodynamic polarization (PDP) technique in phosphate-buffered saline (PBS) solution acidified to pH 3.0 at 37 °C in the presence and absence of 10−2 M Trp, with different immersion times (2 h and 24 h). The amino acid is adsorbed onto the corroded SS surface mainly through the lone electron pair of the nitrogen atom of the indole ring, which adopts a more/less tilted orientation, and the protonated amine group. The visible differences in the intensity of the Fermi doublet upon adsorption of Trp onto the corroded SS surface, which is a sensitive marker of the local environment, suggested that a stronger hydrophobic environment is observed. This may result in an improvement of the corrosion resistance, after 2 h than 24 h of exposure time. The electrochemical results confirm this statement—the inhibition efficiency of Trp, acting as a mixed-type inhibitor, is made drastically higher after a short period of immersion.
1 May 2019 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
In this paper we present a model for local gas assisted focused electron beam induced deposition which allows estimating the surface diffusion coefficient and the residence time of volatile precursor adsorbates. Elaborating the existing continuum model for one adsorbate species and using a novel set of parameters we simplified the differential equation describing the dynamics of this process. We will show that stationary exposure experiments do not allow for a unique determination of the parameters residence time, surface diffusion coefficient, and net cross-section. Rather an estimation of parameter windows is possible by assuming meaningful values for the electron dissociation cross section. The model was applied to the experimental results for Cu(hfac)2 as a gas precursor.