63 results match your criteria small confinements


Towards detection of inflammation in adipose tissue: Microscopic field simulations to estimate water signal properties.

Z Med Phys 2021 Apr 5. Epub 2021 Apr 5.

Section on Experimental Radiology, University of Tübingen, Germany.

Inflammation of adipose tissue, particularly visceral adipose tissue, is assumed to be a causal factor for the development of type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular diseases. Invasive biopsy is currently mandatory for assessment and grading of adipose tissue inflammation. Magnetic resonance detection of the increased water content of inflamed adipose tissue is considered to be a non-invasive alternative. Read More

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Evaporation in nano/molecular materials.

Adv Colloid Interface Sci 2021 Apr 23;290:102385. Epub 2021 Feb 23.

Department of Mechanical Engineering, University of Houston, 4726 Calhoun Rd, Houston, TX 77204, USA. Electronic address:

Evaporation is a physical phenomenon with fundamental significance to both nature and technology ranging from plant transpiration to DNA engineering. Various analytical and empirical relationships have been proposed to characterize evaporation kinetics at macroscopic scales. However, theoretical models to describe the kinetics of evaporation from nano and sub-nanometer (molecular) confinements are absent. Read More

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Integer topological defects of cell monolayers: Mechanics and flows.

Phys Rev E 2021 Jan;103(1-1):012405

Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland.

Monolayers of anisotropic cells exhibit long-ranged orientational order and topological defects. During the development of organisms, orientational order often influences morphogenetic events. However, the linkage between the mechanics of cell monolayers and topological defects remains largely unexplored. Read More

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January 2021

Quantifying Material Properties of Cell Monolayers by Analyzing Integer Topological Defects.

Phys Rev Lett 2021 Jan;126(2):028101

Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland.

In developing organisms, internal cellular processes generate mechanical stresses at the tissue scale. The resulting deformations depend on the material properties of the tissue, which can exhibit long-ranged orientational order and topological defects. It remains a challenge to determine these properties on the time scales relevant for developmental processes. Read More

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January 2021

Tin Nanodots Derived From Sn /Graphene Quantum Dot Complex as Pillars into Graphene Blocks for Ultrafast and Ultrastable Sodium-Ion Storage.

Small 2020 Sep 19;16(38):e2003557. Epub 2020 Aug 19.

School of Materials Science and Engineering, China University of Petroleum, Qingdao, 266580, P. R. China.

Tin (Sn) is considered to be an ideal candidate for the anode of sodium ion batteries. However, the design of Sn-based electrodes with maintained long-term stability still remains challenging due to their huge volume expansion (≈420%) and easy pulverization during cycling. Herein, a facile and versatile strategy for the synthesis of nitrogen-doped graphene quantum dot (GQD) edge-anchored Sn nanodots as the pillars into reduced graphene oxide blocks (NGQD/Sn-NG) for ultrafast and ultrastable sodium-ion storage is reported. Read More

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September 2020

Quantifying Water Friction in Misaligned Graphene Channels under Ångström Confinements.

ACS Appl Mater Interfaces 2020 Aug 22;12(31):35757-35764. Epub 2020 Jul 22.

Micro & Nano-Scale Transport Laboratory, Waterloo Institute for Nanotechnology, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

Two-dimensional (2D) materials, such as graphene (GE), hold great potential to be employed as the fundamental building blocks of novel nanofluidic devices for a wide range of applications. Recent advances in experimental techniques are materializing such prospects by enabling the assembly of 2D material-based fluidic channels with heights as small as few Ångströms. Here, we conduct molecular dynamics simulations to probe the effect of the relative misalignment between the walls of the GE fluidic channel with Ångströms height on the resistance to water transport through the channel. Read More

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Reminiscent capillarity in subnanopores.

Nat Commun 2019 10 11;10(1):4642. Epub 2019 Oct 11.

Université Grenoble Alpes, CNRS, LIPhy, 38000, Grenoble, France.

Fluids in large and small pores display different behaviors with a crossover described through the concept of critical capillarity. Here we report experimental and simulation data for various siliceous zeolites and adsorbates that show unexpected reminiscent capillarity for such nanoporous materials. For pore sizes D exceeding the fluid molecule size, the filling pressures p are found to follow a generic behavior kT ln p ∼ γ/ρD where γ and ρ are the fluid surface tension and density. Read More

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October 2019

Epidermal growth factor-nanoparticle conjugates change the activity from anti-apoptotic to pro-apoptotic at membrane rafts.

Acta Biomater 2019 04 19;88:383-391. Epub 2019 Feb 19.

WPI Research Initiative for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. Electronic address:

The proliferation epidermal growth factor (EGF) is known to acquire contradictory apoptotic activities upon conjugation with gold nanoparticles (GNPs) through hitherto unknown mechanisms. Here, we identified an essential role of membrane rafts in the drastic activity switching of EGF-GNPs through the following intracellular signaling. (1) In contrast to the rapid diffusion of activated EGF receptor after the soluble EGF stimulation, the receptor is confined within membrane rafts upon binding to the EGF-GNPs. Read More

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Phase Transitions in Confinements: Controlling Solid to Fluid Transitions of Xenon Atoms in an On-Surface Network.

Small 2019 Jan 17;15(3):e1803169. Epub 2018 Dec 17.

Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232, Villigen, PSI, Switzerland.

This study reports on "phase" transitions of Xe condensates in on-surface confinements induced by temperature changes and local probe excitation. The pores of a metal-organic network occupied with 1 up to 9 Xe atoms are investigated in their propensity to undergo "condensed solid" to "confined fluid" transitions. Different transition temperatures are identified, which depend on the number of Xe atoms in the condensate and relate to the stability of the Xe clustering in the condensed "phase. Read More

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January 2019

Three-Dimensional Heterogeneous Structure Formation on a Supported Lipid Bilayer Disclosed by Single-Particle Tracking.

Langmuir 2018 10 19;34(39):11857-11865. Epub 2018 Sep 19.

Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States.

Three-dimensional (3D) single-particle tracking was employed to study the lipid membrane morphology change at different pHs on glass supported lipid bilayers (SLBs) [1,2-dioleoyl- sn-glycero-3-phosphoethanolamine/1,2-dioleoyl- sn-glycero-3-phospho-l-serine (sodium salt)/1,2-dioleoyl- sn-glycero-3-phosphocholine = 5:3:2]. Fluorescently tagged, carboxylated polystyrene nanoparticles (of 100 nm) were used as the probes. At neutral pHs, the particles' diffusion was close to two-dimensional Brownian motion, indicating a mainly planar structure of the SLBs. Read More

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October 2018

Alpha-Synuclein Modulates the Physical Properties of DNA.

Chemistry 2018 Oct 19;24(58):15685-15690. Epub 2018 Sep 19.

Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.

Fundamental research on Parkinson's disease (PD) most often focuses on the ability of α-synuclein (aS) to form oligomers and amyloids, and how such species promote brain cell death. However, there are indications that aS also plays a gene-regulatory role in the cell nucleus. Here, the interaction between monomeric aS and DNA in vitro has been investigated with single-molecule techniques. Read More

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October 2018

Thermoelectricity in Heterogeneous Nanofluidic Channels.

Small 2018 05 19;14(21):e1800369. Epub 2018 Apr 19.

Q. Xuesen Laboratory of Space Technology, NO. 104 Youyi Road, Haidian District, Beijing, 100094, China.

Ionic fluids are essential to energy conversion, water desalination, drug delivery, and lab-on-a-chip devices. Ionic transport in nanoscale confinements and complex physical fields still remain elusive. Here, a nanofluidic system is developed using nanochannels of heterogeneous surface properties to investigate transport properties of ions under different temperatures. Read More

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Configurable Integration of On-Chip Quantum Dot Lasers and Subwavelength Plasmonic Waveguides.

Adv Mater 2018 May 6;30(21):e1706546. Epub 2018 Apr 6.

State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing, 100871, China.

The integration of on-chip dielectric lasers and subwavelength plasmonic waveguides has attracted enormous attention because of the combination of both the advantages of the high performances of the small dielectric lasers and the subwavelength plasmonic waveguides. However, the configurable integration is still a challenge owing to the complexity of the hybrid structures and the damageability of the gain media in the multistep micro/nanofabrications. By employing the dark-field optical imaging technique with a position uncertainty of about 21 nm and combining the high-resolution electron beam lithography, the small colloidal quantum dot (CQD) lasers without any damages are accurately aligned with the silver nanowires. Read More

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Frontline Science: Elevated nuclear lamin A is permissive for granulocyte transendothelial migration but not for motility through collagen I barriers.

J Leukoc Biol 2018 08 30;104(2):239-251. Epub 2018 Mar 30.

Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel.

Transendothelial migration (TEM) of lymphocytes and neutrophils is associated with the ability of their deformable nuclei to displace endothelial cytoskeletal barriers. Lamin A is a key intermediate filament component of the nuclear lamina that is downregulated during granulopoiesis. When elevated, lamin A restricts nuclear squeezing through rigid confinements. Read More

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Quantitative image mean squared displacement (iMSD) analysis of the dynamics of profilin 1 at the membrane of live cells.

Methods 2018 05 11;140-141:119-125. Epub 2017 Dec 11.

Centre for Bioactive Discovery in Health and Ageing, School of Science and Technology, University of New England, Armidale, Australia. Electronic address:

Image mean square displacement analysis (iMSD) is a method allowing the mapping of diffusion dynamics of molecules in living cells. However, it can also be used to obtain quantitative information on the diffusion processes of fluorescently labelled molecules and how their diffusion dynamics change when the cell environment is modified. In this paper, we describe the use of iMSD to obtain quantitative data of the diffusion dynamics of a small cytoskeletal protein, profilin 1 (pfn1), at the membrane of live cells and how its diffusion is perturbed when the cells are treated with Cytochalasin D and/or the interactions of pfn1 are modified when its actin and polyphosphoinositide binding sites are mutated (pfn1-R88A). Read More

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High-efficiency broadband excitation and propagation of second-mode spoof surface plasmon polaritons by a complementary structure.

Opt Lett 2017 Jul;42(14):2766-2769

A complementary structure based on coplanar waveguides (CPWs) with periodical etching slots is proposed to support spoof surface plasmon polaritons (SSPPs). In contrast to the traditional slotline-based complementary SSPP structure, a dispersion curve of the second mode by the proposed structure has a much lower starting point from the origin which exhibits greatly improved operating bandwidth. Moreover, tighter confinements of SSPPs in the region of small wave vectors corresponding to lower frequencies can be predicted from the dispersion analysis, which means enhancement of transmission efficiency. Read More

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Activating efficient room temperature phosphorescence of carbon dots by synergism of orderly non-noble metals and dual structural confinements.

Nanoscale 2017 May;9(20):6658-6664

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 100029, Beijing, China.

Obtaining high efficiency room temperature phosphorescence (RTP) by employing non-noble metals poses two challenges: (1) strengthening spin-orbit coupling of excitons to improve the rate of intersystem crossing (ISC) by using non-noble metals with small-atomic-number; (2) employing structural confinement to enhance radiation relaxation because harsh conditions, including carefully selected matrices, rigid solid-state crystalline structure and low temperature, are commonly needed. Here, layered double hydroxides (LDHs) with orderly non-noble metal arrangements were used as an inorganic matrix to activate RTP of carbon dots (CDs). The Zn orderly arranged on the LDH layer contributes to the enhancement in spin-orbit coupling of excitons and the decrease in the energy gap for the singlet-triplet state. Read More

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Gaussian orthogonal ensemble statistics in graphene billiards with the shape of classically integrable billiards.

Phys Rev E 2016 Dec 20;94(6-1):062214. Epub 2016 Dec 20.

School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA.

A crucial result in quantum chaos, which has been established for a long time, is that the spectral properties of classically integrable systems generically are described by Poisson statistics, whereas those of time-reversal symmetric, classically chaotic systems coincide with those of random matrices from the Gaussian orthogonal ensemble (GOE). Does this result hold for two-dimensional Dirac material systems? To address this fundamental question, we investigate the spectral properties in a representative class of graphene billiards with shapes of classically integrable circular-sector billiards. Naively one may expect to observe Poisson statistics, which is indeed true for energies close to the band edges where the quasiparticle obeys the Schrödinger equation. Read More

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December 2016

Glycerol in micellar confinement with tunable rigidity.

J Chem Phys 2016 Dec;145(23):234511

TU Darmstadt, Institut für Festkörperphysik, Hochschulstraße 6, 64289 Darmstadt, Germany.

We investigate the glassy dynamics of glycerol in the confinement of a microemulsion system, which is stable on cooling down to the glass transition of its components. By changing the composition, we vary the viscosity of the matrix, while keeping the confining geometry intact, as is demonstrated by small angle X-ray scattering. By means of H NMR, differential scanning calorimetry, and triplet solvation dynamics we, thus, probe the dynamics of glycerol in confinements of varying rigidity. Read More

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December 2016

Lithographically Defined, Room Temperature Low Threshold Subwavelength Red-Emitting Hybrid Plasmonic Lasers.

Nano Lett 2016 12 29;16(12):7822-7828. Epub 2016 Nov 29.

Tyndall National Institute, University College Cork , Cork, Ireland.

Hybrid plasmonic lasers provide deep subwavelength optical confinement, strongly enhanced light-matter interaction and together with nanoscale footprint promise new applications in optical communication, biosensing, and photolithography. The subwavelength hybrid plasmonic lasers reported so far often use bottom-up grown nanowires, nanorods, and nanosquares, making it difficult to integrate these devices into industry-relevant high density plasmonic circuits. Here, we report the first experimental demonstration of AlGaInP based, red-emitting hybrid plasmonic lasers at room temperature using lithography based fabrication processes. Read More

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December 2016

Structural transitions and hysteresis in clump- and stripe-forming systems under dynamic compression.

Soft Matter 2016 Nov;12(47):9549-9560

Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Using numerical simulations, we study the dynamical evolution of particles interacting via competing long-range repulsion and short-range attraction in two dimensions. The particles are compressed using a time-dependent quasi-one dimensional trough potential that controls the local density, causing the system to undergo a series of structural phase transitions from a low density clump lattice to stripes, voids, and a high density uniform state. The compression proceeds via slow elastic motion that is interrupted with avalanche-like bursts of activity as the system collapses to progressively higher densities via plastic rearrangements. Read More

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November 2016

Correlation energy, correlated electron density, and exchange-correlation potential in some spherically confined atoms.

J Comput Chem 2016 12 12;37(31):2677-2686. Epub 2016 Oct 12.

Departament de Química, Institut de Química Computacional i Catàlisi, Carrer Maria Aurèlia Capmany 69, Universitat de Girona, 17003, Girona, Spain.

We report correlation energies, electron densities, and exchange-correlation potentials obtained from configuration interaction and density functional calculations on spherically confined He, Be, Be , and Ne atoms. The variation of the correlation energy with the confinement radius R is relatively small for the He, Be , and Ne systems. Curiously, the Lee-Yang-Parr (LYP) functional works well for weak confinements but fails completely for small R . Read More

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December 2016

Thermal motion of a nonlinear localized pattern in a quasi-one-dimensional system.

Phys Rev E 2016 Jul 15;94(1-1):012217. Epub 2016 Jul 15.

Laboratoire Matière et Systèmes Complexes, UMR No. 7057, CNRS, Université Paris 7 Diderot, 75205 Paris Cedex 13, France.

We study the dynamics of localized nonlinear patterns in a quasi-one-dimensional many-particle system near a subcritical pitchfork bifurcation. The normal form at the bifurcation is given and we show that these patterns can be described as solitary-wave envelopes. They are stable in a large temperature range and can diffuse along the chain of interacting particles. Read More

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Systematic Limitations in Concentration Analysis via Anomalous Small-Angle X-ray Scattering in the Small Structure Limit.

Polymers (Basel) 2016 Mar 16;8(3). Epub 2016 Mar 16.

Department Chemie, Fakultät für Naturwissenschaften, Universität Paderborn, D-33098 Paderborn, Germany.

Anomalous small angle scattering measurements have been applied to diluted solutions of anionic polyacrylates decorated by specifically-interacting Pb cations, revealing partial collapse of the polyacrylate into pearl-like subdomains with a size on the order of a few nanometers. From the pure-resonant scattering contribution of the Pb cations, and from subsequent analysis of the resonant-invariant, the amount of Pb cations condensed onto the polyanions with respect to the total amount of Pb cations in the solvent was estimated. In order to scrutinize systematic limitations in the determination of the chemical concentrations of resonant scattering counterions in the collapsed phase, Monte Carlo simulations have been performed. Read More

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Polymer segregation under confinement: Influences of macromolecular crowding and the interaction between the polymer and crowders.

J Chem Phys 2015 Oct;143(13):134904

CAS Key Laboratory of Soft Matter Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui Province 230026, People's Republic of China.

Entropy driven polymer segregation in confinements as a model for chromosome separation in bacteria has attracted wide attention; however, the effects of macromolecular crowding and the interaction between the binding protein and the newly replicated DNA on the segregation dynamics are not clear. Using Langevin dynamics simulations, we investigate the influences of crowders and the attractive interaction between the polymer and a small number of crowders on segregation of two overlapping polymers under a cylindrical confinement. We find that the segregation time increases with increasing the volume fraction of crowders due to the slower chain diffusion in crowded environments. Read More

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October 2015

Understanding the electric field control of the electronic and optical properties of strongly-coupled multi-layered quantum dot molecules.

Authors:
Muhammad Usman

Nanoscale 2015 Oct;7(39):16516-29

School of Physics, The University of Melbourne, Parkville, 3010, Melbourne, VIC, Australia.

Strongly-coupled quantum dot molecules (QDMs) are widely employed in the design of a variety of optoelectronic, photovoltaic, and quantum information devices. An efficient and optimized performance of these devices demands engineering of the electronic and optical properties of the underlying QDMs. The application of electric fields offers a way to realise such a control over the QDM characteristics for a desired device operation. Read More

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October 2015

Temperature control in large-internal-diameter scaffolded monolithic columns operated at ultra-high pressures.

J Chromatogr A 2015 Jul 11;1401:60-8. Epub 2015 May 11.

University of Amsterdam, van't Hoff Institute for Molecular Sciences, Analytical-Chemistry Group, Science Park 904, 1098 XH Amsterdam, The Netherlands.

Scaffolding makes it feasible to create organic-polymer monoliths in large confinements, such as wide-bore columns. By creating the scaffold from a metal good heat conductivity inside the column is obtained, which renders the relatively large columns (comparable with 4.6 mm i. Read More

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Confined helium on Lagrange meshes.

Phys Chem Chem Phys 2015 Dec;17(47):31417-26

TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.

The Lagrange-mesh method has the simplicity of a calculation on a mesh and can have the accuracy of a variational method. It is applied to the study of a confined helium atom. Two types of confinement are considered. Read More

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December 2015

Confinement dependent chemotaxis in two-photon polymerized linear migration constructs with highly definable concentration gradients.

Biomed Microdevices 2015 Apr;17(2):30

Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsteds Plads 345E, 2800, Kgs. Lyngby, Denmark.

Dendritic cell chemotaxis is known to follow chemoattractant concentration gradients through tissue of heterogeneous pore sizes, but the dependence of migration velocity on pore size and gradient steepness is not fully understood. We enabled chemotaxis studies for at least 42 hours at confinements relevant to tissue models by two-photon polymerization of linear channel constructs with cross-sections from 10 × 10 μm(2) to 20 × 20 μm(2) inside commercially available chemotaxis analysis chips. Faster directed migration was observed with decreasing channel dimensions despite substantial cell deformation in the narrower channels. Read More

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Phase resetting in duper hamsters: specificity to photic zeitgebers and circadian phase.

J Biol Rhythms 2015 Apr 29;30(2):129-43. Epub 2015 Jan 29.

Department of Biology and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts.

The duper mutation in Syrian hamsters shortens the free-running period of locomotor activity (τDD) to about 23 h and results in a type 0 phase-response curve (PRC) to 15-min light pulses. To determine whether exaggerated phase shifts are specific to photic cues and/or restricted to subjective night, we subjected hamsters to novel wheel confinements and dark pulses during subjective day. Small phase shifts elicited by the nonphotic cue were comparable in mutant and wild-type (WT) hamsters, but dark pulses triggered larger shifts in dupers. Read More

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