Two-Dimensional Flow Nanometry of Biological Nanoparticles for Accurate Determination of Their Size and Emission Intensity

Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and molecular composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging, which is a severe limitation. Surface-sensitive microscopy allows one to precisely determine fluorescence or scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. We here show that attaching BNPs (specifically, vesicles and functionalized gold NPs) to a supported lipid bilayer, subjecting them to a hydrodynamic flow, and tracking their motion via surface-sensitive imaging enable to determine their diffusion coefficients and flow-induced drift velocities and to accurately quantify both BNP size and emission intensity. For vesicles, the high accuracy is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity.Comment: 28 pages, 5 figure

Jack Londons kvinnor

An investigation of the female characters in the fictional works of American author Jack London. The paper mainly focuses on how female characters to some extent must acquire masculine characteristics to be considered valuable - and how they, at the same time, can not deviate too far from their suggested essential femininity

Experiments and calibration of a bond-slip relation and efficiency factors for textile reinforcement in concrete

Textile reinforcement yarns consist of many filaments, which can slip relative each other. At modelling of the global structural behaviour, interfilament slip in the yarns, and slip between the yarns and the concrete can be considered by efficiency factors for the stiffness and strength of the yarns, and by applying a bond-slip relation between yarns and concrete. In this work, an effective and robust method for calibration of such models was developed. Two-sided asymmetrical pull-out tests were carried out, with varying embedment lengths designed to obtain both pull-out and rupture of the textile as failure mode. The efficiency factors for strength and stiffness of the textile were very similar, 34% and 35% respectively. This indicates the stress distribution within a yarn to be uneven in a similar manner for small and large stress levels, and that interfilament slip has a larger influence than variation of filaments’ strength

Barnens prydnad, suomi

Nimiösivulla myös: Suomennos.Ilmestynyt tekijältä aikaisemmin vuonna 1896 nimellä Lasten kaunistus : lasten saarna

A 3D/2D comparison between heterogeneous mesoscale models of concrete

A model for 3D Statistical Volume Elements (SVEs) of mesoscale concrete is presented and employed in the context of computational homogenization. The model is based on voxelization where the SVE is subdivided into a number of voxels (cubes) which are treated as solid finite elements. The homogenized response is compared between 3D and 2D SVEs to study how the third spatial dimension influence the over-all results. The computational results show that the effective diffusivity of the 3D model is about 1.4 times that of the 2D model

Mesoscale modelling of crack-induced diffusivity in concrete

Cracks have large impact on the diffusivity of concrete since they provide low-resistance pathways for moisture and chloride ions to migrate through the material. In this work, crack-induced diffusivity in concrete is modelled on the heterogeneous mesoscale and computationally homogenized to obtain macroscale diffusivity properties. Computations are carried out using the finite element method (FEM) on three-dimensional Statistical Volume Elements (SVEs) comprising the mesoscale constituents in terms of cement paste, aggregates and the Interfacial Transition Zone (ITZ). The SVEs are subjected to uni-axial tension loading and cracks are simulated by use of an isotropic damage model. In a damaged finite element, the crack plane is assumed to be perpendicular to the largest principle strain, and diffusivity properties are assigned to the element only in the in-plane direction of the crack by anisotropic constitutive modelling. The numerical results show that the macroscale diffusivity of concrete can be correlated to the applied mechanical straining of the SVE and that the macroscale diffusivity increases mainly in the transversal direction relative to the axis of imposed mechanical straining

On a volume averaged measure of macroscopic reinforcement slip in two-scale modeling of reinforced concrete

A two-scale model for reinforced concrete, in which the large-scale problem formulation is enriched by an effective reinforcement slip variable, is derived from the single-scale model describing the response of plain concrete, reinforcement steel, as well as the bond between them. The subscale problem on the Representative Volume Element (RVE) is correspondingly defined as finding the response of the RVE subjected to effective variables (strain, slip, and slip gradient) imposed from the large-scale.\ua0 A novel volumetric definition of effective reinforcement slip and its gradient is devised, and the corresponding subscale problem is formulated.\ua0 The newly-defined effective variables are imposed on the RVE in a weak sense via Lagrange multipliers. The response of the RVEs of different sizes was investigated by means of pull-through tests, and the novel boundary condition type was used in FE^2 analyses of a deep beam. Locally, prescribing the macroscopic reinforcement slip and its gradient in the proposed manner resulted in reduced RVE-size dependency of effective work conjugates, which allows for more objective description of reinforcement slip in two-scale modelling of reinforced concrete. Globally, this formulation produced more consistent amplitudes of effective slip fluctuations, as well as more consistent maximum crack width predictions

On Periodic Boundary Conditions in Variationally Consistent Homogenisation of Beams and Plates

A computationally efficient strategy to prescribe periodic boundary conditions on three- dimensional Representative Volume Elements (RVEs) is outlined. In particular, the cases of having an Euler-Bernoulli beam and a Kirchhff-Love plate problem at the macroscale are considered within a computational homogenisation framework. Special solid elements for the boundary region of the periodic mesh have been developed, in which some of the degrees of freedom depend on those of their periodic counterparts, the macroscopic data and the size of the RVE

On Periodic Boundary Conditions in Variationally Consistent Homogenisation of Beams and Plates

A computationally efficient strategy to prescribe periodic boundary conditions on three- dimensional Representative Volume Elements (RVEs) is outlined. In particular, the cases of having an Euler-Bernoulli beam and a Kirchhff-Love plate problem at the macroscale are considered within a computational homogenisation framework. Special solid elements for the boundary region of the periodic mesh have been developed, in which some of the degrees of freedom depend on those of their periodic counterparts, the macroscopic data and the size of the RVE

On Periodic Boundary Conditions in Variationally Consistent Homogenisation of Beams and Plates

A computationally efficient strategy to prescribe periodic boundary conditions on three- dimensional Representative Volume Elements (RVEs) is outlined. In particular, the cases of having an Euler-Bernoulli beam and a Kirchhff-Love plate problem at the macroscale are considered within a computational homogenisation framework. Special solid elements for the boundary region of the periodic mesh have been developed, in which some of the degrees of freedom depend on those of their periodic counterparts, the macroscopic data and the size of the RVE