Materials Literature
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We study the size of polyelectrolyte multilayer capsules as a function of ionic strength, temperature, and time. A dynamic micromechanical model is developed which successfully describes the experiments. The model includes the polymer-solvent surface tension, an electrostatic force which is strongly ionic strength dep…
The phonon dispersion of an isolated linear chain of carbon atoms is studied by density functional theory. It is shown that the longitudinal optical phonon at the $\ensuremath{\Gamma}$ point is affected by Kohn anomaly. Moreover the slope of this phonon branch is modulated by the degree of bond length alternation of t…
The optical dielectric functions for single-crystal ${\mathrm{KTaO}}_{3}$ are determined using spectroscopic ellipsometry and optical transmission techniques. These results show that the lowest band gap is $3.64\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ $(341\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ with very low absorpti…
Monolayer N-propylaniline functionalized mesoporous silica SBA-15 (MFMS) has been successfully used for the grafting of polyaniline moieties through in-situ polymerization in the presence of ammonium peroxodisulfate (APS) as oxidant. For comparison, siliceous SBA-15 has been used to prepare non-grafted polyaniline (PA…
Abstract W 18 O 49 nanowires were synthesized by a high‐temperature physical evaporation technique. The structure, morphology, and composition of the nanowires were characterized by SEM, EMPA, XRD, XPS, and HRTEM techniques. The intrinsic Raman spectrum of W 18 O 49 nanowires was obtained, and the effect of laser powe…
Room-temperature Raman scattering has been measured in barium tungstate $(\mathrm{Ba}\mathrm{W}{\mathrm{O}}_{4})$ up to $16\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. We report the pressure dependence of all the Raman active first-order phonons of the tetragonal scheelite phase ($\mathrm{Ba}\mathrm{W}{\mathrm{O}}_{4}\te…
A new polydentate tripodal ligand T2soxMe was synthesized to take advantage of the chelating effect of tridentate 8-hydroxyquinolinate subunits. Potentiometric and spectrophotometric titrations reveal seven pK(a) values of between 3.7 and 10.2. In water, the use of T2soxMe leads to thermodynamically stable and soluble…
A new critical behavior in unconventional superconductors and superfluids is established and described by the Wilson-Fisher renormalization-group method. For certain symmetries of order a new type of fluctuation-driven first order phase transitions at finite and zero temperature are predicted. The results can be appli…
The magneto-optical spectra of NiMnSb were calculated in the framework of the local spin density approximation (LSDA) combined with dynamical mean-field theory (DMFT). Comparing with results based on the plain LSDA, the additional account of many-body correlations via DMFT results in a noticeably improved agreement of…
How aryl groups attach to a graphene sheet is an experimentally unanswered question. Using first principles density functional theory methods, we shed light on this problem. For the basal plane, isolated phenyl groups are predicted to be weakly bonded to the graphene sheet, even though a new single C-C bond is formed…
We demonstrate novel methods for the study of multiple exciton generation from a single photon absorption event (carrier multiplication) in semiconductor nanocrystals (or nanocrystal quantum dots) that are complementary to our previously reported transient absorption method. By monitoring the time dependence of photol…
The diffraction image of a quasicrystal admits a finite group G as a symmetry group, and the quasicrystal can be regarded as a quasiperiodic packing of copies of a G-cluster C, joined by glue atoms. The physical space E containing C can be embedded into a higher-dimensional space R^k such that, up to an inflation fact…
In this article we present a method to compute the scattering states of holes in spherical bands in the strong spin-orbit coupling regime. More precisely, we calculate scattering phase shifts and amplitudes of holes induced by defects in a semiconductor crystal. We follow a previous work done on this topic by Ralph [H…
The thermodynamical stability of ${\rm Al(BH_4)_3}$ has been investigated using first-principles calculations based on density functional theory. The heats of formation are obtained to be -132 and $-131 {\rm kJ/mol}$ without the zero-point energy corrections for $α$- and $β$-${\rm Al(BH_4)_3}$, respectively, which are…
We investigate theoretically the effects of surface states over the magnetoresistance of Ni-based organic spin-valves. In particular we perform {\it ab initio} electronic transport calculations for a benzene-thiolate molecule chemically attached to a Ni [001] surface and contacted either by Te to another Ni [001] surf…
n -Butanol is an important industrial chemical usually produced by the oxo process, an expensive, energy-consuming set of reactions over metal catalysts, using petrochemical raw materials at high pressure. We developed nonstoichiometric hydroxyapatite (HAP), a highly active calcium phosphate compound and found it cata…
To cap it all: A polycation-free encapsulation method is used to obtain high concentrations of uncomplexed, short oligonucleotide chains confined within monodisperse, degradable microcapsules. Oligonucleotide loadings of >104 chains per capsule are obtained, and more than 90 % of the capsules are filled with DNA. Thes…
Graphene in the quantum Hall regime exhibits a multicomponent structure due to the electronic spin and chirality degrees of freedom. While the applied field breaks the spin symmetry explicitly, we show that the fate of the chirality SU(2) symmetry is more involved: The leading symmetry-breaking terms differ in origin…
Using a combination of an aqueous layer-by-layer deposition technique, nanoparticle surface modification chemistry, and nanoreactor chemistry, we constructed thin film coatings with two distinct layered functional regions: a reservoir for the loading and release of bactericidal chemicals and a nanoparticle surface cap…
We showed directional adhesion on the superhydrophobic wings of the butterfly . A droplet easily rolls off the surface of the wings along the radial outward (RO) direction of the central axis of the body, but is pinned tightly against the RO direction. Interestingly, these two distinct states can be tuned by controlli…