Materials Literature
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It was shown by micromagnetic simulation that a current-driven in-plane magnetized magnetic nano-contact, besides a quasi-linear propagating ("Slonczewski") spin wave mode, can also support a nonlinear self-localized spin wave "bullet" mode that exists in a much wider range of bias currents. The frequency of the "bull…
Three's a crowd: Trimeric silver clusters in aqueous AgNO3 solutions have been identified by mass spectrometry (see picture). These clusters are found to dominate nucleation and thus play an important role in the formation of triangular silver nanoplates, which are shown in the SEM image in the lower right part of the…
No backbone required: A supramolecular hydrogel has been synthesized from a guest-modified cyclodextrin (CD) without a polymer backbone. The β-CD forms supramolecular fibrils through host–guest interactions, and then hydrogen bonds between the CDs cross-link the fibrils to give a hydrogel. Gel-to-sol transitions can b…
Silver platelets and silver-coated gold nanorods 20–100 nm in size (with a 10–20 nm short axis; see figure) have been identified as excellent candidates for surface-enhanced Raman spectroscopy (SERS) substrates. Salt-induced particle aggregation is essential in obtaining high sensitivity.
Supercooled water exhibits a breakdown of the Stokes–Einstein relation between the diffusion constant D and the alpha relaxation time τ α . For water simulated with two different potentials, TIP5P and ST2, we find that the temperature of the decoupling of diffusion and alpha relaxation correlates with the temperature…
The contact angles of liquids and droplets of Lennard-Jones particles on a solid surface are determined by molecular dynamics simulations. The simulations show that the angles of contact are established within the first fluid layer. The droplets are not spherical segment-shaped. For an attractive surface corresponding…
We report a ductile beta-type titanium alloy with body-centered cubic (bcc) crystal structure having a low Poisson's ratio of 0.14. The almost identical ultralow bulk and shear moduli of approximately 24 GPa combined with an ultrahigh strength of approximately 0.9 GPa contribute to easy crystal distortion due to much-…
Small angle neutron scattering (SANS) is used to measure the density of heavy water contained in 1D cylindrical pores of mesoporous silica material MCM-41-S-15, with pores of diameter of 15 ± 1 Å. In these pores the homogenous nucleation process of bulk water at 235 K does not occur, and the liquid can be supercooled…
A simple numerical model which calculates the kinetics of crystallization involving randomly distributed nucleation and isotropic growth is presented. The model can be applied to different thermal histories and no restrictions are imposed on the time and the temperature dependences of the nucleation and growth rates.…
Effect of an anisotropic detachment on a heteroepitaxial island shape is studied by means of a kinetic Monte Carlo simulation of a square lattice gas model. Only with molecular deposition followed by surface diffusion, islands grow in a ramified dendritic shape, similar to DLA. Introduction of molecular detachment fro…
We present a density functional theory based method for calculating NMR shielding tensors for 3d transition metal nuclei using periodic boundary conditions. Calculations employ the gauge-including projector augmented-wave pseudopotentials method. The effects of ultrasoft pseudopotential and induced approximations on t…
Structural features of the charge/orbital ordering $(\mathrm{C}\mathrm{O}∕\mathrm{O}\mathrm{O})$ in single-layered manganites ${\mathrm{Pr}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{1+x}\mathrm{Mn}{\mathrm{O}}_{4}$ $(0.3\ensuremath{\leqslant}x\ensuremath{\leqslant}0.65)$ have been investigated systematically by transmission e…
We present density functional calculations on the molecule based S=1/2 antiferromagnetic chain compound Cu PM(NO3)2 (H2O)2; PM = pyrimidine. The properties of the ferro- and antiferromagnetic state are investigated at the level of the local density approximation and with the hybrid functional B3LYP. Spin density maps…
In trying to assess the structural integrity of electrospun type II collagen scaffolds, a modified but new technique for cross-linking collagen has been developed. Carbodiimides have been previously used to cross-link collagen in gels and in lyophilized native tissue specimens but had not been used for electrospun mat…
Using the first-principles full-potential linearized augmented plane-wave method based on density functional theory, we have investigated the electronic structure and magnetism of hypothetical $M$C ($M=\mathrm{Mg}$, Ca, Sr, and Ba) compounds with the zinc-blende (ZB) crystal structure. It is shown that ZB $\mathrm{CaC…
We present density functional theory (DFT) calculations for MnO, ${\mathrm{Mn}}_{3}{\mathrm{O}}_{4}$, $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Mn}}_{2}{\mathrm{O}}_{3}$, and $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Mn}{\mathrm{O}}_{2}$, using different gradient corrected functionals, such as Perdew-Bur…
Three-dimensional synthetic gels that mimic the extracellular matrix provide a promising tool for studying cell interactions.
We demonstrate a layer-by-layer processing scheme that can be utilized to create transparent superhydrophobic films from SiO2 nanoparticles of various sizes. By controlling the placement and level of aggregation of differently sized nanoparticles within the resultant multilayer thin film, it is possible to optimize th…
Much progress has been made over the past ten years on the synthesis of monodisperse spherical nanocrystals. Mechanistic studies have shown that monodisperse nanocrystals are produced when the burst of nucleation that enables separation of the nucleation and growth processes is combined with the subsequent diffusion-c…
A detailed analysis of the thermal expansion mechanism of graphite oxide to produce functionalized graphene sheets is provided. Exfoliation takes place when the decomposition rate of the epoxy and hydroxyl sites of graphite oxide exceeds the diffusion rate of the evolved gases, thus yielding pressures that exceed the…