Materials Literature
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The local atomic structure of nanoporous carbons produced by pyrolysis of poly(furfuryl alcohol) at various temperatures has been studied using neutron diffraction. Atomic pair distribution functions (PDFs) were obtained from the neutron data. Structure models have been fitted to the PDFs to understand the fine featur…
In this article, we show how colossal magnetoresistance effect (CMR) can be tuned in polycrystalline mixed valence manganite La0.67Ca0.33MnO3 via changing grain size by means of a sol-gel method. Below a critical diameter (150 nm), CMR disappears, but large intergrain MR remains even well above Tc (1.2Tc for ≈95 nm pa…
The misfit relaxation mechanism of BaTiO3 thin films of different thicknesses grown two-dimensionally on SrTiO3(100) substrates by pulsed laser deposition was analysed using X-ray diffraction and transmission electron microscopy. Major defects in partially relaxed films are misfit dislocations with Burgers vectors of…
High-speed heavy plastic deformation of thin foils of fcc metals, including aluminium, is found to produce a high density of small vacancy clusters, in the form of stacking-fault tetrahedra. The dependences of the density of the clusters on the deformation temperature and deformation rate indicate the production of va…
The paper introduces a scalable three-dimensional (3D) kinetic cellular automaton model with a probabilistic switching rule for the spatial and crystallographic prediction of mesoscale transformation phenomena that involve orientational field variables and the motion of sharp interfaces, such as encountered in the fie…
Abstract A procedure for structural investigations by X-ray diffraction of mixed-layer structures incorporating swelling layers has been developed. For each sample, specimens saturated with different cations (Na, Mg, and Ca), are analyzed both as air-dried and as glycolated. One structural model fitting all the observ…
Raman signal intensities from the 997 cm −1 ring breathing mode of thiophenol monolayers adsorbed at Ag, Au, and Pt surfaces were employed for determination of absolute surface enhancement factors (SEFs). Unlike previous estimations of SEFs, these SEFs are determined by referencing the surface-enhanced Raman scatterin…
Absorption spectra have been measured in the near-infrared region for a thin-film sample of single-wall carbon nanotubes of 1.2–1.5 nm diameter. Two absorption peaks are observed at 0.7 and 1.2 eV. The observed spectrum has been compared with the calculation based on the tight-binding model taking into account the dis…
The lamellar grating problem is reformulated through the concept of adaptive spatial resolution. We introduce a new coordinate system such that spatial resolution is increased around the discontinuities of the permittivity function. We derive a new eigenproblem that we solve by using Fourier expansions for both the fi…
The field-emission properties of cold cathodes produced using nano-porous anodic aluminum oxide (AAO) templates are reported. Several types of field emitters were fabricated: aligned copper nanowires grown halfway up the parallel nano-pores of the AAO; aligned multiwalled carbon nanotubes grown to the top of the pores…
Synthetic biodegradable polymers offer an alternative to the use of autografts, allografts, and nondegradable materials for bone replacement. They can be synthesized with tailored mechanical and degradative properties. They also can be processed to porous scaffolds with desired pore morphologic features conducive to t…
Will the interface between the physical and life sciences be where progress in future technologies takes place? An indication of this is provided by the first report of nanocrystal assembly based on protein binding. The gold nanocrystals of an aqueous dispersion are modified by chemisorption of a modified biotin and s…
The three omega thermal conductivity measurement method is analyzed for the case of one or more thin films on a substrate of finite thickness. The analysis is used to obtain the thermal conductivities of SiO2 films on Si substrates and of a chemical vapor deposition (CVD) diamond plate. For the case of the SiO2 films…
The design of a high resolution photoemission electron microscope (PEEM) for the study of magnetic materials is described. PEEM is based on imaging the photoemitted (secondary) electrons from a sample irradiated by x rays. This microscope is permanently installed at the Advanced Light Source at a bending magnet that d…
Nine different sol‐gel derived carbon xerogels were prepared with different pore structures by varying the carbonization temperature (in flowing N 2 ) and activation time (in 5 % CO 2 in N 2 ). For each of these carbon xerogels, mesopore and micropore size distributions and cumulative surface areas were extracted from…
A new human 33-kDa serine protease was purified from human epidermis, and its cDNA was cloned from a keratinocyte library, from mRNA from a human keratinocyte line (HaCat) and from mRNA from human skin. Polyclonal antibodies specific for the new protein detected three groups of proteins in partially purified extracts…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDirect Growth of Single-Walled Carbon Nanotube Scanning Probe Microscopy TipsJason H. Hafner, Chin Li Cheung, and Charles M. LieberView Author Information Department of Chemistry and Chemical Biology Harvard University, Cambridge, Massachusetts 02138 Cite this: J. Am.…
Recent advances in ab initio direct methods have enabled the solution of crystal structures of small proteins from native X-ray data alone, that is, without the use of fragments of known structure or the need to prepare heavy-atom or selenomethionine derivatives, provided that the data are available to atomic resoluti…
Columbite route for synthesis of P3MgNb2O9 (PMN) allows the suppression of secondary phases in PMN powders. These phases, having low dielectric constant, affect negatively the dielectric properties of PMN ceramics. Aiming to get reactive PMN powders, the partial oxalate method was used to precipitate lead oxalate over…
In this work, the influence of the additive system on the liquid phase sintering of silicon carbide has been investigated. The additives employed were mixtures of AlN/Y2O3, Al2O3/Y2O3 and SiO2/Y2O3. The total additive content was fixed at 20 vol.-%, maintaining the Y2O3 content in each additive system at 35 vol.-%. Co…