30 research outputs found
Synthesis of Liquid Core–Shell Particles and Solid Patchy Multicomponent Particles by Shearing Liquids Into Complex Particles (SLICE)
No full textWe report a simple method that uses (i) emulsion shearing with oxidation to make core–shell particles, and (ii) emulsion shearing with surface-tension driven phase segregation to synthesize particles with complex surface compositions and morphologies. Subjecting eutectic gallium–indium, a liquid metal, to shear in an acidic carrier fluid we synthesized smooth liquid core–shell particles 6.4 nm to over 10 μm in diameter. Aggregates of these liquid particles can be reconfigured into larger structures using a focused ion beam. Using Field’s metal melts we synthesized homogeneous nanoparticles and solid microparticles with different surface roughness and/or composition through shearing and phase separation. This extension of droplet emulsion technique, SLICE, applies fluidic shear to create micro- and nanoparticles in a tunable, green, and low-cost approach.Reprinted with permission from Tevis, Ian D., Lucas B. Newcomb, and Martin Thuo. "Synthesis of Liquid Core–Shell Particles and Solid Patchy Multicomponent Particles by Shearing Liquids Into Complex Particles (SLICE)." Langmuir 30, no. 47 (2014): 14308-14313, doi:10.1021/la5035118. Copyright 2014 American Chemical Society.</p
Atomic Reconstruction of Au Thin Films through Interfacial Strains
No full textInterfaces play a critical thermodynamic role in the existence of multilayer systems. Due to its utility in bridging energetic and compositional differences between distinct species, the formation of interfaces inherently creates internal strain towards bulk atoms due to the reorganization needed to accommodate such interface. We report the effect of scaling interfacial stress due to deposition of different adlayers on a host thin metal film. Intrinsic property differences between host and de-posited metal atoms result in varying degree of composition and energy gradient within the interface. Interfacial stress can increase defects in the host leading to; i) energy dissipation and reorganization to minimize surface energy, ii) increased material strength. We infer that dissipation of interfacial stress induces defect migration, hence bulk and surface atomic reconstruction as captured by the surface roughness and grain size reduction coupled with concomitant increase in material strength.This is a manuscript of the article published as Martin, Andrew, Jiahao Chen, Chuanshen Du, Manish Kumar, Ian D. Tevis, Boyce Chang, Sid Pathak, and Martin M. Thuo. "Atomic Reconstruction of Au Thin Films through Interfacial Strains." Nano Letters 24, no. 6 (2024): 1967-1973. doi: https://doi.org/10.1021/acs.nanolett.3c04412
Assembled Monolayers Depends upon the Roughness of the Substrate and the Orientation of the Terminal Moiety
No full textThe origin of the odd even effect in properties of self-assembled monolayers (SAMs) and/or technologies derived from them is poorly understood. We report that hydrophobicity and, hence, surface wetting of SAMs are dominated by the nature of the substrate (surface roughness and identity) and SAM tilt angle, which influences surface dipoles/orientation of the terminal moiety. We measured static contact angles (theta(s)) made by water droplets on n-alkanethiolate SAMs with an odd (SAM(O)) or even (SAM(E)) number of carbons (average theta(s) range of 105.8-112.1 degrees). When SAMs were fabricated on smooth "template-stripped" metal (M-TS) surfaces [root-mean-square (rms) roughness = 0.36 +/- 0.01 nm for Au-TS and 0.60 +/- 0.04 nm for Ag-TS], the odd-even effect, characterized by a zigzag oscillation in values of theta(s), was observed. We, however, did not observe the same effect with rougher "as-deposited" (M-AD) surfaces (rms roughness = 2.27 +/- 0.16 nm for Au-AD and 5.13 +/- 0.22 nm for Ag-AD). The odd-even effect in hydrophobicity inverts when the substrate changes from Au-TS (higher theta(s) for SAM(E) than SAM(O), with average Delta theta(s) (vertical bar n - (n + 1)vertical bar) approximate to 3 degrees) to Ag-TS (higher theta(s) for SAM(O) than SAM(E), with average Delta theta(s) (vertical bar n - (n + 1)vertical bar) approximate to 2 degrees). A comparison of hydrophobicity across Ag-TS and Au-TS showed a statistically significant difference (Student's t test) between SAM(E) (Delta theta(s) (vertical bar Ag evens - Au evens vertical bar) approximate to 5 degrees; P 0.1). From these results, we deduce that the roughness of the metal substrate (from comparison of M-AD versus M-TS) and orientation of the terminal -CH2CH3 (by comparing SAM(E) and SAM(O) on Au-TS versus Ag-TS) play major roles in the hydrophobicity and, by extension, general wetting properties of n-alkanethiolate SAMs.Reprinted with permission from Newcomb, Lucas B., Ian D. Tevis, Manza BJ Atkinson, Symon M. Gathiaka, Rafael E. Luna, and Martin Thuo. "Odd–even effect in the hydrophobicity of n-alkanethiolate self-assembled monolayers depends upon the roughness of the substrate and the orientation of the terminal moiety." Langmuir 30, no. 40 (2014): 11985-11992, doi:10.1021/la5032569. Copyright 2014 American Chemical Society.</p
Patterning of periodic high-aspect-ratio nanopores in anatase titanium dioxide from titanium fluoride hydrolysis
No full textMechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering
No full textPhase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate ('/'=physisorbed, '-'=chemisorbed), from molten Field's metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso-and micro-scale at ambient conditions without heat or electricity
Fabrication of core-shell undercooled metal particles and their use in manufacturing and joining at ambient conditions
No full textFabrication of core-shell undercooled metal particles and their use in manufacturing and joining at ambient conditions
No full textSearch for a heavy composite Majorana neutrino in the final state with two leptons and two quarks at root s=13 TeV
No full textA search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton-proton collisions at root s = 13 TeVis presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3 fb(-1). The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, N-l, stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, m(Nl), and the compositeness scale Lambda. For the case m(Nl) = Lambda, the existence of N-e (N-mu) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level. (C) 2017 The Author(s). Published by Elsevier B.V
Search for a heavy composite Majorana neutrino in the final state with two leptons and two quarks at <tex>\sqrt{s}$</tex>=13 TeV
No full textAbstract: A search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton-proton collisions at root s = 13 TeVis presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3 fb(-1). The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, N-l, stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, m(Nl), and the compositeness scale Lambda. For the case m(Nl) = Lambda, the existence of N-e (N-mu) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level. (C) 2017 The Author(s). Published by Elsevier B.V
Search for a heavy composite Majorana neutrino in the final state with two leptons and two quarks at root s=13 TeV
No full textA search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton-proton collisions at root s = 13 TeVis presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3 fb(-1). The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, N-l, stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, m(Nl), and the compositeness scale Lambda. For the case m(Nl) = Lambda, the existence of N-e (N-mu) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level. (C) 2017 The Author(s). Published by Elsevier B.V
