Materials Literature
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New procedures are outlined that enable ARP/wARP to automatically build protein models with diffraction data extending to about 2.5 A. An overview of ongoing research is given and possible future advances are discussed.
Large databases that can be used in the search for new materials with specific properties remain an elusive goal in materials science. The problem is complicated by the fact that the optimal material for a given application is usually a compromise between a number of materials properties and the cost. In this letter w…
High-density ZnO nanowires (ZnONWs) were aligned onto Au-catalyzed Si substrate through a simple low-temperature physical vapor deposition method. Scanning electron microscope (SEM) observations, x-ray diffraction (XRD) analysis, and photoluminescence spectra showed that the ZnONWs were single-crystalline, with a hexa…
This letter describes a simple procedure for fabricating randomly and uniaxially aligned nanofibers of nickel ferrite by electrospinning. Polycrystalline nanofibers of NiFe2O4 with an average diameter of 46 nm have been prepared by electrospinning a solution that contained poly(vinyl pyrrolidone) and alkoxide precurso…
The aim of this work is to investigate the electron transport through metal–ferroelectric–metal (MFM) junctions with ultrathin barriers in order to determine its dependence on the polarization state of the barrier. To that end, heteroepitaxial Pt/Pb(Zr0.52Ti0.48)O3/SrRuO3 junctions have been fabricated on lattice-matc…
We propose a simple analytical formula that can quantitatively predict resonant light scattering from metal nanoparticles of arbitrary shape, whose sizes are too large for Rayleigh approximation to be applicable. The formula has been derived as an empirical extension of Mie’s rigorous calculation for light scattering…
In this letter, a planar left-handed propagating medium consisting of a coplanar waveguide (CPW) inductively coupled to split ring resonators (SRR) and periodically loaded with narrow metallic wires is proposed. The wires make the structure behave as a microwave plasma with a negative effective permittivity which cove…
We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this syste…
A new software system called PHENIX (Python-based Hierarchical ENvironment for Integrated Xtallography) is being developed for the automation of crystallographic structure solution. This will provide the necessary algorithms to proceed from reduced intensity data to a refined molecular model, and facilitate structure…
The software SOLVE and RESOLVE can carry out all the steps in macromolecular structure solution, from scaling and heavy-atom location through phasing, density modification and model-building in the MAD, SAD and MIR cases. SOLVE uses scoring scheme to convert the decision-making in macromolecular structure solution to…
Wrapping of carbon nanotubes (CNTs) by single-stranded DNA (ssDNA) was found to be sequence-dependent. A systematic search of the ssDNA library selected a sequence d(GT)n, n = 10 to 45 that self-assembles into a helical structure around individual nanotubes in such a way that the electrostatics of the DNA-CNT hybrid d…
Reflection profiles were analyzed from microgravity-grown ( micro g) and earth-grown insulin crystals to measure mosaicity (eta) and to reveal mosaic domain structure and composition. The effects of cryocooling on single-domain and multi-domain crystals were compared. The effects of cryocooling on insulin structure we…
The hybrid cluster protein (HCP) from the sulfate-reducing bacteria Desulfovibrio desulfuricans ATCC 27774 has been isolated and crystallized anaerobically. The protein sample used in the crystallization studies was several months old, having been stored at 193 K, and initial crystal structure studies were unable to f…
Abstract The effect of the chemical modification of the silica surface by the silane coupling agent (Si69) on both the real and the imaginary parts of the shear compliance ( J′ , J″ ) on silica‐filled butyl rubber vulcanizates was investigated in a wide temperature and frequency range, −70 to 120 °C and 10 −4 to 10 Hz…
Sodium intercalation into the oxide slabs of the cation-deficient n = 2 Ruddlesden−Popper oxysulfide Y 2 Ti 2 O 5 S 2 to produce α-Na x Y 2 Ti 2 O 5 S 2 (0 < x ≤ 1.0) is reported. These materials have been probed as a function of the amount of intercalated sodium using high-resolution neutron powder diffraction. At al…
Abstract Silicon nanoparticles were produced by a relatively low temperature (164 °C), solution-phase synthesis. The particles exhibit UV to blue photoluminescence (PL) which varied with excitation wavelength. The average lifetimes, excited at 300 nm, ranged from 4.4 to 5.9 ns. The mean particle diameter, determined b…
Dissimilatory sulfite reductase D (DsrD) from Desulfovibrio vulgaris has been crystallized for a neutron diffraction study. The initial crystals obtained were too small for the neutron experiment. In order to obtain a larger crystal (>1 mm3), a combination of two techniques was developed to determine the optimum cryst…
Plants of the Dorstenia genus, used in traditional medicine and as food ingredient in Africa, are rich in polyphenolic compounds which can be involved in prevention of disease and food spoilage through their antioxidant activity. The antiradical activities of extracts of Dorstenia psilurus. D. ciliata and a phenolic c…
A random tunneling algorithm (RTA) is derived from the terminal repeller unconstrained subenergy tunneling (TRUST) algorithm, and the parallelization of the RTA is implemented with an island parallel paradigm. Combined with the techniques of angular moving, the parallel random tunneling algorithm (PRTA) is applied to…
Structural refinement of proteins involves the minimization of a target function that combines X-ray data with a set of restraints enforcing stereochemistry and packing. Electrostatic interactions are not ordinarily included in the target function, partly because they cannot be calculated reliably without a descriptio…