Materials Literature
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DNA replication initiator proteins bind site specifically to origin sites and in most cases participate in the early steps of unwinding the duplex. The papillomavirus preinitiation complex that assembles on the origin of replication is composed of proteins E1 and the activator protein E2. E2 is an ancillary factor tha…
Diatoms are unicellular organisms encased by silica‐based cell walls that display species‐specific structures. Morphogenesis of diatom cell walls is believed to be controlled by a polysaccharide/protein‐matrix that remains associated with mature cell walls. Recently, a family of calcium‐binding glycoproteins, the frus…
The crystal structure of a high-pressure Fe 3 O 4 phase was determined by in situ X-ray diffraction measurements at high pressure and temperature, using an imaging plate detector and monochromatic synchrotron X-radiation. The high-pressure phase has the Pbcm space group (CaMn 2 O 4 -type structure) with cell parameter…
Phenyl substituents in the 6-positions of terpyridine ligands are important for controlling the spin state of their iron(II) complexes. The introduction of phenyl substituents in both the 6- and 6″-positions leads exclusively to the orange high-spin iron(II) complexes, whilst the presence of a single 6-phenyl substitu…
Abstract Homogeneous nucleation of CaSO 4 ·2H 2 O (gypsum) based on an optical diagnostic technique was studied within a supersaturation range of 1–4 at 25–90°C. The experiments were carried out using an experimental apparatus consisting of a batch crystallizer with the related measurement devices. Signals of scattere…
The high-temperature phases of the perovskites sodium niobate, NaNbO(3), and sodium tantalate, NaTaO(3), have been re-examined using the high-resolution powder diffractometer HRPD at the ISIS neutron spallation source; the two materials show the same sequence of phases with tilted octahedra. Diffraction patterns were…
We report on experiments on the rheology of gels formed by diffusion-limited aggregation of neutrally buoyant colloidal particles. These gels form very weak solids, with the elastic modulus, ${G}^{\ensuremath{'}}(\ensuremath{\omega})$, larger than the loss modulus, ${G}^{\ensuremath{'}\ensuremath{'}}(\ensuremath{\omeg…
A high-quality Si−MCM-41 was prepared with the composition of SiO 2, 0.2; TEAOH, 0.25; CTMABr, 35 in H 2 O using fumed silica as the silica source. The quality of the compounds was assessed using different analytical techniques such as XRD, N 2 adsorption−desorption measurement, UV−vis absorption, FTIR, and 29 Si MAS…
Extending the considerations of previous work (Acta Polym. 1997, 48, 30; Acta Polym. 1997, 48, 298) the degree of branching (DB) and the average number of branches per non-terminal monomer unit (ANB) are defined and calculated for random copolycondensation of ABm with AB monomers as well as ABm with ABn-monomers in ge…
We consider the double exchange for systems in which doped electrons occupy degenerate orbitals, treating the realistic situation with double degenerate ${e}_{g}$ orbitals. We show that the orbital degeneracy leads in general to the formation of anisotropic magnetic structures and that, in particular, depending on the…
A method for the determination of absorbed radiation dose is described based on pulsed optically stimulated luminescence (POSL). The method relies upon the stimulation of an irradiated sample with a train of light pulses from a suitable light source (e.g. a laser) using a wavelength which is within the range of wavele…
The Poisson-Boltzmann model of colloidal bodies in electrolyte is the basis of a recent numerical calculation predicting attraction between two colloidal spheres confined in a cylinder. The present study formulates an analytical proof that this model cannot predict attraction. Our exact result, not contingent upon app…
Zr 62−x Ti x Cu 20 Ni 8 Al 10 (3⩽x⩽5) amorphous alloys crystallize via precipitation of icosahedral quasicrystals in the primary crystallization step, leading to nano-sized quasicrystals embedded in an amorphous matrix. Ti is the decisive component favoring the precipitation of quasicrystals. The mechanical properties…
A careful analysis of the classic Derjaguin-Landau-Verwey-Overbeek theory of the interaction energy in a suspension of charge-stabilized, spherical colloidal particles (polyions) in the presence of salt shows that in addition to the usual screened-Coulomb effective pair interaction between polyions, there exists a str…
We derive a spin-orbital model for insulating ${\mathrm{LaMnO}}_{3}$ which fulfills the SU(2) symmetry of $S=2$ spins at ${\mathrm{Mn}}^{3+}$ ions. It includes the complete ${e}_{g}$ and ${t}_{2g}$ superexchange which follows from a realistic ${\mathrm{Mn}}^{2+}$ multiplet structure in cubic site symmetry, and the Jah…
We calculate the ideal-glass-transition line for adhesive hard spheres in the temperature-volume-fraction plane within the framework of the mode-coupling theory. We find two intersecting lines, controlled by the hard-core and the adhesive parts of the potential respectively, giving rise to two different mechanisms for…
Fluids adsorbed in microporous materials can exhibit quantum sieving, where heavy isotopes are preferentially adsorbed over light isotopes. We present the first detailed predictions of quantum sieving based on realistic models of microporous materials. Carbon nanotubes, and the interstices of nanotube bundles, can act…
Quantum-dot solids and polycrystalline semiconductors that are patterned in three dimensions can be produced by the new route described here. Both materials have potential as photonic crystals. The method combines colloidal chemistry with two steps of hierarchical selfassembly: first, semiconductor nanocrystals are in…