Transition-Metal-Doped NIR-Emitting Silicon Nanocrystals

Impurity-doping in nanocrystals significantly affects their electronic properties and diversifies their applications. Herein, we report the synthesis of transition metal (Mn, Ni, Co, Cu)-doped oleophilic silicon nanocrystals (SiNCs) through hydrolysis/polymerization of triethoxysilane with acidic aqueous metal salt solutions, followed by thermal disproportionation of the resulting gel into a doped-Si/SiO2 composite that, upon HF etching and hydrosilylation with 1-n-octadecene, produces free-standing octadecyl-capped doped SiNCs (diameter approximate to 3 to 8 nm; dopant <0.2 atom %). Metal-doping triggers a red-shift of the SiNC photoluminescence (PL) of up to 270 nm, while maintaining high PL quantum yield (26% for Co doping).Peer reviewe

Sustainable super-hard and thick nanodiamond composite film deposited on cemented carbide substrates with an interfacial Al-interlayer.

Super-hard nanodiamond composite (NDC) films, synthesized via cathodic arc plasma deposition on unheated WC−Co substrates, offer an eco-friendly solution for cutting tools. A 100 nm-thick Al-interlayer mitigates Co catalytic effects, improving adhesion and yielding smooth and dense 10 µm-thick films at a deposition rate of 3.3μm/hr. These grain-boundary-rich nanostructured films, with an impressive 58 GPa hardness attributed to a substantial 70% C sp3 fraction, prove optimal for hard coatings. The Al-interlayer effectively suppresses Co catalytic effects, forming a dense Al-oxide layer, enhancing film hardness and adhesion (Lcr=18.6N). NDC films present a promising eco-friendly option for high-performance hard coatings

Efficient boron removal by using mesoporous matrices grafted with saccharides

Highly efficient boron removal from water was achieved by using mesoporous silica materials functionalised with saccharides.Beltran Porter, Daniel, [email protected] ; Amoros del Toro, Pedro Jose, [email protected]

Use of MMG signals for the control of powered orthotic devices: Development of a rectus femoris measurement protocol

Copyright © 2009 Rehabilitation Engineering and Assistive Technology Society (RESNA). This is an Author's Accepted Manuscript of an article published in Assistive Technology, 21(1), 1 - 12, 2009, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/10400430902945678.A test protocol is defined for the purpose of measuring rectus femoris mechanomyographic (MMG) signals. The protocol is specified in terms of the following: measurement equipment, signal processing requirements, human postural requirements, test rig, sensor placement, sensor dermal fixation, and test procedure. Preliminary tests of the statistical nature of rectus femoris MMG signals were performed, and Gaussianity was evaluated by means of a two-sided Kolmogorov-Smirnov test. For all 100 MMG data sets obtained from the testing of two volunteers, the null hypothesis of Gaussianity was rejected at the 1%, 5%, and 10% significance levels. Most skewness values were found to be greater than 0.0, while all kurtosis values were found to be greater than 3.0. A statistical convergence analysis also performed on the same 100 MMG data sets suggested that 25 MMG acquisitions should prove sufficient to statistically characterize rectus femoris MMG. This conclusion is supported by the qualitative characteristics of the mean rectus femoris MMG power spectral densities obtained using 25 averages

Influence of residual Ga_2O_3 and Cs on the increase in the maximum quantum efficiency of NEA-GaAs by a two-step thermal cleaning process

We investigated the relationship between the increase in the maximum quantum efficiency of negative electron affinity (NEA)-GaAs depending on the thermal cleaning conditions and residual species, e.g., Ga_2O_3 and Cs atoms, on the GaAs surface using temperature-programmed desorption. We found that the increase in the maximum quantum efficiency occurs during thermal cleaning at 500–600℃ for ～8.5 min. The increase in ratio was maximum when the amount of Ga_2O_3 on the GaAs surface was maximum. In the case that Cs atoms remained, when the thermal cleaning was performed in a temperature range where Ga_2O_3 was not formed, the effect facilitating an NEA surface formation was observed. However, the residual Cs atoms might not be affected at an increased maximum quantum efficiency. From the above results, we considered that the double-dipole structures of Cs-Ga_2O_3 and Cs-O are significant to the high quantum efficiency. The Cs-O dipoles are considered to form easily when Ga_2O_3 is on the GaAs surface before the NEA activation, and the amount of Cs-O dipoles required to reduce the vacuum level below the conduction band minimum increase more than usually NEA surface. As a result, the maximum quantum efficiency increases

Investigation of the mechanism of chromium removal in (3-aminopropyl)trimethoxysilane functionalized mesoporous silica

We are proposed that a possible mechanism for Cr(VI) removal by functionalized mesoporous silica. Mesoporous silica was functionalized with (3-aminopropyl)trimethoxysilane (APTMS) using the post-synthesis grafting method. The synthesized materials were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), N-2 adsorption-desorption analysis, Fourier-transform infrared (FT-IR), thermogravimetric analyses (TGA), and X-ray photoelectron spectroscopy (XPS) to confirm the pore structure and functionalization of amine groups, and were subsequently used as adsorbents for the removal of Cr(VI) from aqueous solution. As the concentration of APTMS increases from 0.01 M to 0.25 M, the surface area of mesoporous silica decreases from 857.9 m(2)/g to 402.6 m(2)/g. In contrast, Cr(VI) uptake increases from 36.95 mg/g to 83.50 mg/g. This indicates that the enhanced Cr(VI) removal was primarily due to the activity of functional groups. It is thought that the optimum concentration of APTMS for functionalization is approximately 0.05 M. According to XPS data, NH3+ and protonated NH2 from APTMS adsorbed anionic Cr(VI) by electrostatic interaction and changed the solution pH. Equilibrium data are well fitted by Temkin and Sips isotherms. This research shows promising results for the application of amino functionalized mesoporous silica as an adsorbent to removal Cr(VI) from aqueous solution