TY - JOUR
AB - The epitaxial growth of a strained Ge layer, which is a promising candidate for the channel material of a hole spin qubit, has been demonstrated on 300 mm Si wafers using commercially available Si0.3Ge0.7 strain relaxed buffer (SRB) layers. The assessment of the layer and the interface qualities for a buried strained Ge layer embedded in Si0.3Ge0.7 layers is reported. The XRD reciprocal space mapping confirmed that the reduction of the growth temperature enables the 2-dimensional growth of the Ge layer fully strained with respect to the Si0.3Ge0.7. Nevertheless, dislocations at the top and/or bottom interface of the Ge layer were observed by means of electron channeling contrast imaging, suggesting the importance of the careful dislocation assessment. The interface abruptness does not depend on the selection of the precursor gases, but it is strongly influenced by the growth temperature which affects the coverage of the surface H-passivation. The mobility of 2.7 × 105 cm2/Vs is promising, while the low percolation density of 3 × 1010 /cm2 measured with a Hall-bar device at 7 K illustrates the high quality of the heterostructure thanks to the high Si0.3Ge0.7 SRB quality.
AU - Shimura, Yosuke
AU - Godfrin, Clement
AU - Hikavyy, Andriy
AU - Li, Roy
AU - Aguilera Servin, Juan L
AU - Katsaros, Georgios
AU - Favia, Paola
AU - Han, Han
AU - Wan, Danny
AU - de Greve, Kristiaan
AU - Loo, Roger
ID - 15018
IS - 5
JF - Materials Science in Semiconductor Processing
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - General Materials Science
SN - 1369-8001
TI - Compressively strained epitaxial Ge layers for quantum computing applications
VL - 174
ER -
TY - JOUR
AB - High entropy alloys (HEAs) are highly suitable candidate catalysts for oxygen evolution and reduction reactions (OER/ORR) as they offer numerous parameters for optimizing the electronic structure and catalytic sites. Herein, FeCoNiMoW HEA nanoparticles are synthesized using a solution‐based low‐temperature approach. Such FeCoNiMoW nanoparticles show high entropy properties, subtle lattice distortions, and modulated electronic structure, leading to superior OER performance with an overpotential of 233 mV at 10 mA cm−2 and 276 mV at 100 mA cm−2. Density functional theory calculations reveal the electronic structures of the FeCoNiMoW active sites with an optimized d‐band center position that enables suitable adsorption of OOH* intermediates and reduces the Gibbs free energy barrier in the OER process. Aqueous zinc–air batteries (ZABs) based on this HEA demonstrate a high open circuit potential of 1.59 V, a peak power density of 116.9 mW cm−2, a specific capacity of 857 mAh gZn−1, and excellent stability for over 660 h of continuous charge–discharge cycles. Flexible and solid ZABs are also assembled and tested, displaying excellent charge–discharge performance at different bending angles. This work shows the significance of 4d/5d metal‐modulated electronic structure and optimized adsorption ability to improve the performance of OER/ORR, ZABs, and beyond.
AU - He, Ren
AU - Yang, Linlin
AU - Zhang, Yu
AU - Jiang, Daochuan
AU - Lee, Seungho
AU - Horta, Sharona
AU - Liang, Zhifu
AU - Lu, Xuan
AU - Ostovari Moghaddam, Ahmad
AU - Li, Junshan
AU - Ibáñez, Maria
AU - Xu, Ying
AU - Zhou, Yingtang
AU - Cabot, Andreu
ID - 14434
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - A 3d‐4d‐5d high entropy alloy as a bifunctional oxygen catalyst for robust aqueous zinc–air batteries
ER -
TY - JOUR
AB - Low‐cost, safe, and environmental‐friendly rechargeable aqueous zinc‐ion batteries (ZIBs) are promising as next‐generation energy storage devices for wearable electronics among other applications. However, sluggish ionic transport kinetics and the unstable electrode structure during ionic insertion/extraction hampers their deployment. Herein, we propose a new cathode material based on a layered metal chalcogenide (LMC), bismuth telluride (Bi2Te3), coated with polypyrrole (PPy). Taking advantage of the PPy coating, the Bi2Te3@PPy composite presents strong ionic absorption affinity, high oxidation resistance, and high structural stability. The ZIBs based on Bi2Te3@PPy cathodes exhibit high capacities and ultra‐long lifespans of over 5000 cycles. They also present outstanding stability even under bending. In addition, we analyze here the reaction mechanism using in situ X‐ray diffraction, X‐ray photoelectron spectroscopy, and computational tools and demonstrate that, in the aqueous system, Zn2+ is not inserted into the cathode as previously assumed. In contrast, proton charge storage dominates the process. Overall, this work not only shows the great potential of LMCs as ZIBs cathode materials and the advantages of PPy coating, but also clarifies the charge/discharge mechanism in rechargeable ZIBs based on LMCs.
AU - Zeng, Guifang
AU - Sun, Qing
AU - Horta, Sharona
AU - Wang, Shang
AU - Lu, Xuan
AU - Zhang, Chaoyue
AU - Li, Jing
AU - Li, Junshan
AU - Ci, Lijie
AU - Tian, Yanhong
AU - Ibáñez, Maria
AU - Cabot, Andreu
ID - 14435
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - A layered Bi2Te3@PPy cathode for aqueous zinc ion batteries: Mechanism and application in printed flexible batteries
ER -
TY - JOUR
AB - Multistable systems are characterized by exhibiting domain coexistence, where each domain accounts for the different equilibrium states. In case these systems are described by vectorial fields, domains can be connected through topological defects. Vortices are one of the most frequent and studied topological defect points. Optical vortices are equally relevant for their fundamental features as beams with topological features and their applications in image processing, telecommunications, optical tweezers, and quantum information. A natural source of optical vortices is the interaction of light beams with matter vortices in liquid crystal cells. The rhythms that govern the emergence of matter vortices due to fluctuations are not established. Here, we investigate the nucleation mechanisms of the matter vortices in liquid crystal cells and establish statistical laws that govern them. Based on a stochastic amplitude equation, the law for the number of nucleated vortices as a function of anisotropy, voltage, and noise level intensity is set. Experimental observations in a nematic liquid crystal cell with homeotropic anchoring and a negative anisotropic dielectric constant under the influence of a transversal electric field show a qualitative agreement with the theoretical findings.
AU - Aguilera, Esteban
AU - Clerc, Marcel G.
AU - Zambra, Valeska
ID - 11343
JF - Nonlinear Dynamics
KW - Electrical and Electronic Engineering
KW - Applied Mathematics
KW - Mechanical Engineering
KW - Ocean Engineering
KW - Aerospace Engineering
KW - Control and Systems Engineering
SN - 0924-090X
TI - Vortices nucleation by inherent fluctuations in nematic liquid crystal cells
VL - 108
ER -
TY - JOUR
AB - We investigate the local self-sustained process underlying spiral turbulence in counter-rotating Taylor–Couette flow using a periodic annular domain, shaped as a parallelogram, two of whose sides are aligned with the cylindrical helix described by the spiral pattern. The primary focus of the study is placed on the emergence of drifting–rotating waves (DRW) that capture, in a relatively small domain, the main features of coherent structures typically observed in developed turbulence. The transitional dynamics of the subcritical region, far below the first instability of the laminar circular Couette flow, is determined by the upper and lower branches of DRW solutions originated at saddle-node bifurcations. The mechanism whereby these solutions self-sustain, and the chaotic dynamics they induce, are conspicuously reminiscent of other subcritical shear flows. Remarkably, the flow properties of DRW persist even as the Reynolds number is increased beyond the linear stability threshold of the base flow. Simulations in a narrow parallelogram domain stretched in the azimuthal direction to revolve around the apparatus a full turn confirm that self-sustained vortices eventually concentrate into a localised pattern. The resulting statistical steady state satisfactorily reproduces qualitatively, and to a certain degree also quantitatively, the topology and properties of spiral turbulence as calculated in a large periodic domain of sufficient aspect ratio that is representative of the real system.
AU - Wang, B.
AU - Ayats López, Roger
AU - Deguchi, K.
AU - Mellibovsky, F.
AU - Meseguer, A.
ID - 12137
JF - Journal of Fluid Mechanics
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - Applied Mathematics
SN - 0022-1120
TI - Self-sustainment of coherent structures in counter-rotating Taylor–Couette flow
VL - 951
ER -
TY - JOUR
AB - In the class of strictly convex smooth boundaries each of which has no strip around its boundary foliated by invariant curves, we prove that the Taylor coefficients of the “normalized” Mather’s β-function are invariant under C∞-conjugacies. In contrast, we prove that any two elliptic billiard maps are C0-conjugate near their respective boundaries, and C∞-conjugate, near the boundary and away from a line passing through the center of the underlying ellipse. We also prove that, if the billiard maps corresponding to two ellipses are topologically conjugate, then the two ellipses are similar.
AU - Koudjinan, Edmond
AU - Kaloshin, Vadim
ID - 12145
IS - 6
JF - Regular and Chaotic Dynamics
KW - Mechanical Engineering
KW - Applied Mathematics
KW - Mathematical Physics
KW - Modeling and Simulation
KW - Statistical and Nonlinear Physics
KW - Mathematics (miscellaneous)
SN - 1560-3547
TI - On some invariants of Birkhoff billiards under conjugacy
VL - 27
ER -
TY - JOUR
AB - Supramolecular self-assembly in biological systems holds promise to convert and amplify disease-specific signals to physical or mechanical signals that can direct cell fate. However, it remains challenging to design physiologically stable self-assembling systems that demonstrate tunable and predictable behavior. Here, the use of zwitterionic tetrapeptide modalities to direct nanoparticle assembly under physiological conditions is reported. The self-assembly of gold nanoparticles can be activated by enzymatic unveiling of surface-bound zwitterionic tetrapeptides through matrix metalloprotease-9 (MMP-9), which is overexpressed by cancer cells. This robust nanoparticle assembly is achieved by multivalent, self-complementary interactions of the zwitterionic tetrapeptides. In cancer cells that overexpress MMP-9, the nanoparticle assembly process occurs near the cell membrane and causes size-induced selection of cellular uptake mechanism, resulting in diminished cell growth. The enzyme responsiveness, and therefore, indirectly, the uptake route of the system can be programmed by customizing the peptide sequence: a simple inversion of the two amino acids at the cleavage site completely inactivates the enzyme responsiveness, self-assembly, and consequently changes the endocytic pathway. This robust self-complementary, zwitterionic peptide design demonstrates the use of enzyme-activated electrostatic side-chain patterns as powerful and customizable peptide modalities to program nanoparticle self-assembly and alter cellular response in biological context.
AU - Huang, Richard H.
AU - Nayeem, Nazia
AU - He, Ye
AU - Morales, Jorge
AU - Graham, Duncan
AU - Klajn, Rafal
AU - Contel, Maria
AU - O'Brien, Stephen
AU - Ulijn, Rein V.
ID - 13355
IS - 1
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - Self‐complementary zwitterionic peptides direct nanoparticle assembly and enable enzymatic selection of endocytic pathways
VL - 34
ER -
TY - JOUR
AB - In this paper, we explore the stability and dynamical relevance of a wide variety of steady, time-periodic, quasiperiodic, and chaotic flows arising between orthogonally stretching parallel plates. We first explore the stability of all the steady flow solution families formerly identified by Ayats et al. [“Flows between orthogonally stretching parallel plates,” Phys. Fluids 33, 024103 (2021)], concluding that only the one that originates from the Stokesian approximation is actually stable. When both plates are shrinking at identical or nearly the same deceleration rates, this Stokesian flow exhibits a Hopf bifurcation that leads to stable time-periodic regimes. The resulting time-periodic orbits or flows are tracked for different Reynolds numbers and stretching rates while monitoring their Floquet exponents to identify secondary instabilities. It is found that these time-periodic flows also exhibit Neimark–Sacker bifurcations, generating stable quasiperiodic flows (tori) that may sometimes give rise to chaotic dynamics through a Ruelle–Takens–Newhouse scenario. However, chaotic dynamics is unusually observed, as the quasiperiodic flows generally become phase-locked through a resonance mechanism before a strange attractor may arise, thus restoring the time-periodicity of the flow. In this work, we have identified and tracked four different resonance regions, also known as Arnold tongues or horns. In particular, the 1 : 4 strong resonance region is explored in great detail, where the identified scenarios are in very good agreement with normal form theory.
AU - Wang, B.
AU - Ayats López, Roger
AU - Meseguer, A.
AU - Marques, F.
ID - 12146
IS - 11
JF - Physics of Fluids
KW - Condensed Matter Physics
KW - Fluid Flow and Transfer Processes
KW - Mechanics of Materials
KW - Computational Mechanics
KW - Mechanical Engineering
SN - 1070-6631
TI - Phase-locking flows between orthogonally stretching parallel plates
VL - 34
ER -
TY - JOUR
AB - Several Ising-type magnetic van der Waals (vdW) materials exhibit stable magnetic ground states. Despite these clear experimental demonstrations, a complete theoretical and microscopic understanding of their magnetic anisotropy is still lacking. In particular, the validity limit of identifying their one-dimensional (1-D) Ising nature has remained uninvestigated in a quantitative way. Here we performed the complete mapping of magnetic anisotropy for a prototypical Ising vdW magnet FePS3 for the first time. Combining torque magnetometry measurements with their magnetostatic model analysis and the relativistic density functional total energy calculations, we successfully constructed the three-dimensional (3-D) mappings of the magnetic anisotropy in terms of magnetic torque and energy. The results not only quantitatively confirm that the easy axis is perpendicular to the ab plane, but also reveal the anisotropies within the ab, ac, and bc planes. Our approach can be applied to the detailed quantitative study of magnetism in vdW materials.
AU - Nauman, Muhammad
AU - Kiem, Do Hoon
AU - Lee, Sungmin
AU - Son, Suhan
AU - Park, J-G
AU - Kang, Woun
AU - Han, Myung Joon
AU - Jo, Youn Jung
ID - 9282
IS - 3
JF - 2D Materials
KW - Mechanical Engineering
KW - General Materials Science
KW - Mechanics of Materials
KW - General Chemistry
KW - Condensed Matter Physics
SN - 2053-1583
TI - Complete mapping of magnetic anisotropy for prototype Ising van der Waals FePS3
VL - 8
ER -
TY - JOUR
AB - Solution synthesis of particles emerged as an alternative to prepare thermoelectric materials with less demanding processing conditions than conventional solid-state synthetic methods. However, solution synthesis generally involves the presence of additional molecules or ions belonging to the precursors or added to enable solubility and/or regulate nucleation and growth. These molecules or ions can end up in the particles as surface adsorbates and interfere in the material properties. This work demonstrates that ionic adsorbates, in particular Na⁺ ions, are electrostatically adsorbed in SnSe particles synthesized in water and play a crucial role not only in directing the material nano/microstructure but also in determining the transport properties of the consolidated material. In dense pellets prepared by sintering SnSe particles, Na remains within the crystal lattice as dopant, in dislocations, precipitates, and forming grain boundary complexions. These results highlight the importance of considering all the possible unintentional impurities to establish proper structure-property relationships and control material properties in solution-processed thermoelectric materials.
AU - Liu, Yu
AU - Calcabrini, Mariano
AU - Yu, Yuan
AU - Genç, Aziz
AU - Chang, Cheng
AU - Costanzo, Tommaso
AU - Kleinhanns, Tobias
AU - Lee, Seungho
AU - Llorca, Jordi
AU - Cojocaru‐Mirédin, Oana
AU - Ibáñez, Maria
ID - 10123
IS - 52
JF - Advanced Materials
KW - mechanical engineering
KW - mechanics of materials
KW - general materials science
SN - 0935-9648
TI - The importance of surface adsorbates in solution‐processed thermoelectric materials: The case of SnSe
VL - 33
ER -
TY - JOUR
AB - We derive optimal-order homogenization rates for random nonlinear elliptic PDEs with monotone nonlinearity in the uniformly elliptic case. More precisely, for a random monotone operator on \mathbb {R}^d with stationary law (that is spatially homogeneous statistics) and fast decay of correlations on scales larger than the microscale \varepsilon >0, we establish homogenization error estimates of the order \varepsilon in case d\geqq 3, and of the order \varepsilon |\log \varepsilon |^{1/2} in case d=2. Previous results in nonlinear stochastic homogenization have been limited to a small algebraic rate of convergence \varepsilon ^\delta . We also establish error estimates for the approximation of the homogenized operator by the method of representative volumes of the order (L/\varepsilon )^{-d/2} for a representative volume of size L. Our results also hold in the case of systems for which a (small-scale) C^{1,\alpha } regularity theory is available.
AU - Fischer, Julian L
AU - Neukamm, Stefan
ID - 10549
IS - 1
JF - Archive for Rational Mechanics and Analysis
KW - Mechanical Engineering
KW - Mathematics (miscellaneous)
KW - Analysis
SN - 0003-9527
TI - Optimal homogenization rates in stochastic homogenization of nonlinear uniformly elliptic equations and systems
VL - 242
ER -
TY - JOUR
AB - We report the observation of an anomalous nonlinear optical response of the prototypical three-dimensional topological insulator bismuth selenide through the process of high-order harmonic generation. We find that the generation efficiency increases as the laser polarization is changed from linear to elliptical, and it becomes maximum for circular polarization. With the aid of a microscopic theory and a detailed analysis of the measured spectra, we reveal that such anomalous enhancement encodes the characteristic topology of the band structure that originates from the interplay of strong spin–orbit coupling and time-reversal symmetry protection. The implications are in ultrafast probing of topological phase transitions, light-field driven dissipationless electronics, and quantum computation.
AU - Baykusheva, Denitsa Rangelova
AU - Chacón, Alexis
AU - Lu, Jian
AU - Bailey, Trevor P.
AU - Sobota, Jonathan A.
AU - Soifer, Hadas
AU - Kirchmann, Patrick S.
AU - Rotundu, Costel
AU - Uher, Ctirad
AU - Heinz, Tony F.
AU - Reis, David A.
AU - Ghimire, Shambhu
ID - 13996
IS - 21
JF - Nano Letters
KW - Mechanical Engineering
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
KW - Bioengineering
SN - 1530-6984
TI - All-optical probe of three-dimensional topological insulators based on high-harmonic generation by circularly polarized laser fields
VL - 21
ER -
TY - JOUR
AB - Recent discoveries have shown that, when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between them, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating phonon polaritons–hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a vdW crystal (α-MoO3) supporting anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources. Our images reveal that, under a critical angle, the PhPs isofrequency curve undergoes a topological transition, in which the propagation of PhPs is strongly guided (canalization regime) along predetermined directions without geometric spreading. These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nanoimaging, (bio)-sensing, or heat management.
AU - Duan, Jiahua
AU - Capote-Robayna, Nathaniel
AU - Taboada-Gutiérrez, Javier
AU - Álvarez-Pérez, Gonzalo
AU - Prieto Gonzalez, Ivan
AU - Martín-Sánchez, Javier
AU - Nikitin, Alexey Y.
AU - Alonso-González, Pablo
ID - 10866
IS - 7
JF - Nano Letters
KW - Mechanical Engineering
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
KW - Bioengineering
SN - 1530-6984
TI - Twisted nano-optics: Manipulating light at the nanoscale with twisted phonon polaritonic slabs
VL - 20
ER -
TY - THES
AB - Fabrication of curved shells plays an important role in modern design, industry, and science. Among their remarkable properties are, for example, aesthetics of organic shapes, ability to evenly distribute loads, or efficient flow separation. They find applications across vast length scales ranging from sky-scraper architecture to microscopic devices. But, at
the same time, the design of curved shells and their manufacturing process pose a variety of challenges. In this thesis, they are addressed from several perspectives. In particular, this thesis presents approaches based on the transformation of initially flat sheets into the target curved surfaces. This involves problems of interactive design of shells with nontrivial mechanical constraints, inverse design of complex structural materials, and data-driven modeling of delicate and time-dependent physical properties. At the same time, two newly-developed self-morphing mechanisms targeting flat-to-curved transformation are presented.
In architecture, doubly curved surfaces can be realized as cold bent glass panelizations. Originally flat glass panels are bent into frames and remain stressed. This is a cost-efficient fabrication approach compared to hot bending, when glass panels are shaped plastically. However such constructions are prone to breaking during bending, and it is highly
nontrivial to navigate the design space, keeping the panels fabricable and aesthetically pleasing at the same time. We introduce an interactive design system for cold bent glass façades, while previously even offline optimization for such scenarios has not been sufficiently developed. Our method is based on a deep learning approach providing quick
and high precision estimation of glass panel shape and stress while handling the shape
multimodality.
Fabrication of smaller objects of scales below 1 m, can also greatly benefit from shaping originally flat sheets. In this respect, we designed new self-morphing shell mechanisms transforming from an initial flat state to a doubly curved state with high precision and detail. Our so-called CurveUps demonstrate the encodement of the geometric information
into the shell. Furthermore, we explored the frontiers of programmable materials and showed how temporal information can additionally be encoded into a flat shell. This allows prescribing deformation sequences for doubly curved surfaces and, thus, facilitates self-collision avoidance enabling complex shapes and functionalities otherwise impossible.
Both of these methods include inverse design tools keeping the user in the design loop.
AU - Guseinov, Ruslan
ID - 8366
KW - computer-aided design
KW - shape modeling
KW - self-morphing
KW - mechanical engineering
SN - 2663-337X
TI - Computational design of curved thin shells: From glass façades to programmable matter
ER -
TY - JOUR
AB - Advances in shape-morphing materials, such as hydrogels, shape-memory polymers and light-responsive polymers have enabled prescribing self-directed deformations of initially flat geometries. However, most proposed solutions evolve towards a target geometry without considering time-dependent actuation paths. To achieve more complex geometries and avoid self-collisions, it is critical to encode a spatial and temporal shape evolution within the initially flat shell. Recent realizations of time-dependent morphing are limited to the actuation of few, discrete hinges and cannot form doubly curved surfaces. Here, we demonstrate a method for encoding temporal shape evolution in architected shells that assume complex shapes and doubly curved geometries. The shells are non-periodic tessellations of pre-stressed contractile unit cells that soften in water at rates prescribed locally by mesostructure geometry. The ensuing midplane contraction is coupled to the formation of encoded curvatures. We propose an inverse design tool based on a data-driven model for unit cells’ temporal responses.
AU - Guseinov, Ruslan
AU - McMahan, Connor
AU - Perez Rodriguez, Jesus
AU - Daraio, Chiara
AU - Bickel, Bernd
ID - 7262
JF - Nature Communications
KW - Design
KW - Synthesis and processing
KW - Mechanical engineering
KW - Polymers
SN - 2041-1723
TI - Programming temporal morphing of self-actuated shells
VL - 11
ER -
TY - JOUR
AB - We demonstrate a method for manipulating small ensembles of vortices in multiply connected superconducting structures. A micron-size magnetic particle attached to the tip of a silicon cantilever is used to locally apply magnetic flux through the superconducting structure. By scanning the tip over the surface of the device and by utilizing the dynamical coupling between the vortices and the cantilever, a high-resolution spatial map of the different vortex configurations is obtained. Moving the tip to a particular location in the map stabilizes a distinct multivortex configuration. Thus, the scanning of the tip over a particular trajectory in space permits nontrivial operations to be performed, such as braiding of individual vortices within a larger vortex ensemble—a key capability required by many proposals for topological quantum computing.
AU - Polshyn, Hryhoriy
AU - Naibert, Tyler
AU - Budakian, Raffi
ID - 10622
IS - 8
JF - Nano Letters
KW - mechanical engineering
KW - condensed matter physics
KW - general materials science
KW - general chemistry
KW - bioengineering
SN - 1530-6984
TI - Manipulating multivortex states in superconducting structures
VL - 19
ER -
TY - JOUR
AB - For the Restricted Circular Planar 3 Body Problem, we show that there exists an open set U in phase space of fixed measure, where the set of initial points which lead to collision is O(μ120) dense as μ→0.
AU - Guardia, Marcel
AU - Kaloshin, Vadim
AU - Zhang, Jianlu
ID - 8418
IS - 2
JF - Archive for Rational Mechanics and Analysis
KW - Mechanical Engineering
KW - Mathematics (miscellaneous)
KW - Analysis
SN - 0003-9527
TI - Asymptotic density of collision orbits in the Restricted Circular Planar 3 Body Problem
VL - 233
ER -
TY - JOUR
AB - The ability to reversibly assemble nanoparticles using light is both fundamentally interesting and important for applications ranging from reversible data storage to controlled drug delivery. Here, the diverse approaches that have so far been developed to control the self-assembly of nanoparticles using light are reviewed and compared. These approaches include functionalizing nanoparticles with monolayers of photoresponsive molecules, placing them in photoresponsive media capable of reversibly protonating the particles under light, and decorating plasmonic nanoparticles with thermoresponsive polymers, to name just a few. The applicability of these methods to larger, micrometer-sized particles is also discussed. Finally, several perspectives on further developments in the field are offered.
AU - Bian, Tong
AU - Chu, Zonglin
AU - Klajn, Rafal
ID - 13366
IS - 20
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - The many ways to assemble nanoparticles using light
VL - 32
ER -
TY - JOUR
AB - Efficient isomerization of photochromic molecules often requires conformational freedom and is typically not available under solvent-free conditions. Here, we report a general methodology allowing for reversible switching of such molecules on the surfaces of solid materials. Our method is based on dispersing photochromic compounds within polysilsesquioxane nanowire networks (PNNs), which can be fabricated as transparent, highly porous, micrometer-thick layers on various substrates. We found that azobenzene switching within the PNNs proceeded unusually fast compared with the same molecules in liquid solvents. Efficient isomerization of another photochromic system, spiropyran, from a colorless to a colored form was used to create reversible images in PNN-coated glass. The coloration reaction could be induced with sunlight and is of interest for developing “smart” windows.
AU - Chu, Zonglin
AU - Klajn, Rafal
ID - 13370
IS - 10
JF - Nano Letters
KW - Mechanical Engineering
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
KW - Bioengineering
SN - 1530-6984
TI - Polysilsesquioxane nanowire networks as an “Artificial Solvent” for reversible operation of photochromic molecules
VL - 19
ER -
TY - JOUR
AB - Biological membranes typically contain a large number of different components dispersed in small concentrations in the main membrane phase, including proteins, sugars, and lipids of varying geometrical properties. Most of these components do not bind the cargo. Here, we show that such “inert” components can be crucial for the precise control of cross-membrane trafficking. Using a statistical mechanics model and molecular dynamics simulations, we demonstrate that the presence of inert membrane components of small isotropic curvatures dramatically influences cargo endocytosis, even if the total spontaneous curvature of such a membrane remains unchanged. Curved lipids, such as cholesterol, as well as asymmetrically included proteins and tethered sugars can, therefore, actively participate in the control of the membrane trafficking of nanoscopic cargo. We find that even a low-level expression of curved inert membrane components can determine the membrane selectivity toward the cargo size and can be used to selectively target membranes of certain compositions. Our results suggest a robust and general method of controlling cargo trafficking by adjusting the membrane composition without needing to alter the concentration of receptors or the average membrane curvature. This study indicates that cells can prepare for any trafficking event by incorporating curved inert components in either of the membrane leaflets.
AU - Curk, Tine
AU - Wirnsberger, Peter
AU - Dobnikar, Jure
AU - Frenkel, Daan
AU - Šarić, Anđela
ID - 10359
IS - 9
JF - Nano Letters
KW - mechanical engineering
KW - condensed matter physics
SN - 1530-6984
TI - Controlling cargo trafficking in multicomponent membranes
VL - 18
ER -
TY - JOUR
AB - The novel electronic state of the canted antiferromagnetic (AFM) insulator, strontium iridate (Sr2IrO4) has been well described by the spin-orbit-entangled isospin Jeff = 1/2, but the role of isospin in transport phenomena remains poorly understood. In this study, antiferromagnet-based spintronic functionality is demonstrated by combining unique characteristics of the isospin state in Sr2IrO4. Based on magnetic and transport measurements, large and highly anisotropic magnetoresistance (AMR) is obtained by manipulating the antiferromagnetic isospin domains. First-principles calculations suggest that electrons whose isospin directions are strongly coupled to in-plane net magnetic moment encounter the isospin mismatch when moving across antiferromagnetic domain boundaries, which generates a high resistance state. By rotating a magnetic field that aligns in-plane net moments and removes domain boundaries, the macroscopically-ordered isospins govern dynamic transport through the system, which leads to the extremely angle-sensitive AMR. As with this work that establishes a link between isospins and magnetotransport in strongly spin-orbit-coupled AFM Sr2IrO4, the peculiar AMR effect provides a beneficial foundation for fundamental and applied research on AFM spintronics.
AU - Lee, Nara
AU - Ko, Eunjung
AU - Choi, Hwan Young
AU - Hong, Yun Jeong
AU - Nauman, Muhammad
AU - Kang, Woun
AU - Choi, Hyoung Joon
AU - Choi, Young Jai
AU - Jo, Younjung
ID - 9066
IS - 52
JF - Advanced Materials
KW - Mechanical Engineering
KW - General Materials Science
KW - Mechanics of Materials
SN - 0935-9648
TI - Antiferromagnet‐based spintronic functionality by controlling isospin domains in a layered perovskite iridate
VL - 30
ER -
TY - JOUR
AB - Dissipative self-assembly leads to structures and materials that exist away from equilibrium by continuously exchanging energy and materials with the external environment. Although this mode of self-assembly is ubiquitous in nature, where it gives rise to functions such as signal processing, motility, self-healing, self-replication, and ultimately life, examples of dissipative self-assembly processes in man-made systems are few and far between. Herein, recent progress in developing diverse synthetic dissipative self-assembly systems is discussed. The systems reported thus far can be categorized into three classes, in which: i) the fuel chemically modifies the building blocks, thus triggering their self-assembly, ii) the fuel acts as a template interacting with the building blocks noncovalently, and iii) transient states are induced by the addition of two mutually exclusive stimuli. These early studies give rise to materials that would be difficult to obtain otherwise, including hydrogels with programmable lifetimes, vesicular nanoreactors, and membranes exhibiting transient conductivity.
AU - De, Soumen
AU - Klajn, Rafal
ID - 13375
IS - 41
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - Dissipative self-assembly driven by the consumption of chemical fuels
VL - 30
ER -
TY - JOUR
AB - Dual-responsive nanoparticles are designed by functionalizing magnetic cores with light-responsive ligands. These materials respond to both light and magnetic fields and can be assembled into various higher-order structures, depending on the relative contributions of these two stimuli.
AU - Das, Sanjib
AU - Ranjan, Priyadarshi
AU - Maiti, Pradipta Sankar
AU - Singh, Gurvinder
AU - Leitus, Gregory
AU - Klajn, Rafal
ID - 13406
IS - 3
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - Dual-responsive nanoparticles and their self-assembly
VL - 25
ER -
TY - JOUR
AB - The reversible molecular template-directed self-assembly of gold nanoparticles (AuNPs), a process which relies solely on noncovalent bonding interactions, has been demonstrated by high-resolution transmission electron microscopy (HR-TEM). By employing a well-known host−guest binding motif, the AuNPs have been systemized into discrete dimers, trimers, and tetramers. These nanoparticulate twins, triplets, and quadruplets, which can be disassembled and reassembled either chemically or electrochemically, can be coalesced into larger, permanent polygonal structures by thermal treatment using a focused HR-TEM electron beam.
AU - Olson, Mark A.
AU - Coskun, Ali
AU - Klajn, Rafal
AU - Fang, Lei
AU - Dey, Sanjeev K.
AU - Browne, Kevin P.
AU - Grzybowski, Bartosz A.
AU - Stoddart, J. Fraser
ID - 13416
IS - 9
JF - Nano Letters
KW - Mechanical Engineering
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
KW - Bioengineering
SN - 1530-6984
TI - Assembly of polygonal nanoparticle clusters directed by reversible noncovalent bonding interactions
VL - 9
ER -
TY - JOUR
AB - Reaction-diffusion (RD) processes initiated from the surfaces of mesoscopic particles can fabricate complex core-and-shell structures. The propagation of a sharp RD front selectively removes metal colloids or nanoparticles from the supporting gel or polymer matrix. Once fabricated, the core structures can be processed “remotely” via galvanic replacement reactions, and the composite particles can be assembled into open-lattice crystals.
AU - Wesson, Paul J.
AU - Soh, Siowling
AU - Klajn, Rafal
AU - Bishop, Kyle J. M.
AU - Gray, Timothy P.
AU - Grzybowski, Bartosz A.
ID - 13419
IS - 19
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - “Remote” fabrication via three-dimensional reaction-diffusion: Making complex core-and-shell particles and assembling them into open-lattice crystals
VL - 21
ER -
TY - JOUR
AB - The interaction of tidal currents with sea-floor topography results in the radiation of internal gravity waves into the ocean interior. These waves are called internal tides and their dissipation due to nonlinear wave breaking and concomitant three-dimensional turbulence could play an important role in the mixing of the abyssal ocean, and hence in controlling the large-scale ocean circulation.
As part of on-going work aimed at providing a theory for the vertical distribution of wave breaking over sea-floor topography, in this paper we investigate the instability of internal tides in a very simple linear model that helps us to relate the formation of unstable regions to simple features in the sea-floor topography. For two-dimensional tides over one-dimensional topography we find that the formation of overturning instabilities is closely linked to the singularities in the topography shape and that it is possible to have stable waves at the sea floor and unstable waves in the ocean interior above.
For three-dimensional tides over two-dimensional topography there is in addition an effect of geometric focusing of wave energy into localized regions of high wave amplitude, and we investigate this focusing effect in simple examples. Overall, we find that the distribution of unstable wave breaking regions can be highly non-uniform even for very simple idealized topography shapes.
AU - Bühler, Oliver
AU - Muller, Caroline J
ID - 9149
JF - Journal of Fluid Mechanics
KW - mechanical engineering
KW - mechanics of materials
KW - condensed matter physics
SN - 0022-1120
TI - Instability and focusing of internal tides in the deep ocean
VL - 588
ER -
TY - JOUR
AB - Hydrogel stamps can microstructure solid surfaces, i.e., modify the surface topology of metals, glasses, and crystals. It is demonstrated that stamps soaked in an appropriate etchant can remove material with micrometer-scale precision. The Figure shows an array of concentric circles etched in glass using the immersion wet stamping process described (scale bar: 500 μm).
AU - Smoukov, S. K.
AU - Bishop, K. J. M.
AU - Klajn, Rafal
AU - Campbell, C. J.
AU - Grzybowski, B. A.
ID - 13431
IS - 11
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - Cutting into solids with micropatterned gels
VL - 17
ER -
TY - JOUR
AB - Micropatterning of surfaces with several chemicals at different spatial locations usually requires multiple stamping and registration steps. Here, we describe an experimental method based on reaction–diffusion phenomena that allows for simultaneous micropatterning of a substrate with several coloured chemicals. In this method, called wet stamping (WETS), aqueous solutions of two or more inorganic salts are delivered onto a film of dry, ionically doped gelatin from an agarose stamp patterned in bas relief. Once in conformal contact, these salts diffuse into the gelatin, where they react to give deeply coloured precipitates. Separation of colours in the plane of the surface is the consequence of the differences in the diffusion coefficients, the solubility products, and the amounts of different salts delivered from the stamp, and is faithfully reproduced by a theoretical model based on a system of reaction–diffusion partial differential equations. The multicolour micropatterns are useful as non-binary optical elements, and could potentially form the basis of new applications in microseparations and in controlled delivery.
AU - Klajn, Rafal
AU - Fialkowski, Marcin
AU - Bensemann, Igor T.
AU - Bitner, Agnieszka
AU - Campbell, C. J.
AU - Bishop, Kyle
AU - Smoukov, Stoyan
AU - Grzybowski, Bartosz A.
ID - 13435
JF - Nature Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
SN - 1476-1122
TI - Multicolour micropatterning of thin films of dry gels
VL - 3
ER -
TY - JOUR
AB - Thin films of ionically doped gelatin have been color-patterned with submicrometer precision using the wet-stamping technique. Inorganic salts are delivered onto the gelatin surface from an agarose stamp, and diffuse into the gelatine layer, producting deeply colored precipitates. Reaction fronts originating from different features of the stamp cease within < 1 μm of each other, leaving sharp, transparent regions in between.
AU - Campbell, C. J.
AU - Fialkowski, M.
AU - Klajn, Rafal
AU - Bensemann, I. T.
AU - Grzybowski, B. A.
ID - 13434
IS - 21
JF - Advanced Materials
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 0935-9648
TI - Color micro- and nanopatterning with counter-propagating reaction-diffusion fronts
VL - 16
ER -