Materials Literature
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The synthesis of a novel series of copolymers containing push−pull bisazobenzene (BAz) and monoazobenzene (MAz) groups with various N -alkyl donor groups and with spacers of two and four methylene units is presented, and the effects of the structural variables on the mesomorphic properties of the polymers are investig…
Although there have been numerous materials systems studied as potential candidates for hydrogen storage applications, none of the materials known to date has demonstrated enough hydrogen capacity or efficiency at required operating temperature ranges. There are still considerable opportunities for discovery of new ma…
We study the pressure-induced phase transition of the layered GeS structure using a constant-pressure ab initio technique. For the first time, we predict a gradual phase transition to a Cmcm structure with the application of hydrostatic pressure. The high-pressure phase is still a layered structure, consisting of rock…
A Monte Carlo procedure is described that generates random structure factors with simulated errors corresponding to an X-ray data set of a protein of a specific size and given heavy-atom content. The simulated data set can be used to estimate Bijvoet ratios and figures of merit as obtained from SAD phasing routines an…
Porcine insulin differs in sequence from bovine insulin at residues A8 (Thr in porcine-->Ala in bovine) and A10 (Ile in porcine-->Val in bovine). The structure of T6 hexameric bovine insulin has been determined to 2.25 A resolution at room temperature and refined to a residual of 0.162. The structure of the independen…
The in situ Fourier transform infrared (in situ FTIR) technique was used for the first time to investigate the break-in phenomenon observed for polypyrrole/poly(vinyl sulfonate) (PPy/PVS) films in acetonitrile containing 0.1 M LiClO(4). Consecutive potential scans provided a continuous increase of the infrared band in…
We present an analytical and numerical study of the problem of mechanical impulse propagation through a horizontal alignment of progressively shrinking (tapered) elastic spheres that are placed between two rigid end walls. The studies are confined to cases where initial loading between the spheres is zero (i.e., in th…
Ordered arrays of Bi/Sb superlattice nanowires with diameters of about 50 nm have been produced by pulsed electrodeposition technique into the pores of anodic alumina membrane (AAM). The structure of Bi/Sb superlattice nanowire can be modulated by controlling the electrodeposition conditions.
Three well-defined adsorption sites have been found on opened single-wall carbon nanotubes by temperature-programmed desorption measurements for several alkanes. A series of linear chain alkanes from pentane to nonane, as well as a branched alkane molecule, 2,2,4-trimethylpentane, were used to elucidate the effect of…
We have systematically synthesized single-crystalline thin films of layered perovskites Sr2MO4 (M = Ti, V, Cr, Mn, and Co) which cannot be obtained in a form of bulk crystal apart from M = Mn. The two-dimensional electronic structure of these M4+ oxides, ranging from a correlated insulator to a ferromagnetic metal, ha…
High-performance composite foams of carbon nanofiber-reinforced poly(ether ether ketone) have been produced for the first time (see Figure). The nanofibers perform two roles: optimization of the rheological properties of the polymer melt to allow foaming and improvement of the mechanical properties of the polymer. Thi…
We present simultaneous near-field photoluminescence (PL) and Raman imaging of single-walled carbon nanotubes (SWNTs) with a spatial resolution better than 15 nm. Highly localized excitation is used to visualize the spatial extent of the contributing excited states. For SWNTs on glass, we typically observe highly conf…
An experimental study is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800-900°C. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of 64cm2 per cell. The e…
Large band gap semiconductors are typically doped in order to enhance their photocatalytic, photovoltaic, and other chemical and optoelectronic properties. The identification of dopant position and its local environment are essential to explore the effect of doping. X ray techniques, including extended x ray absorptio…
Hollow octahedrons of polyaniline (PANI) were prepared using Cu2O as a template in the presence of H3PO4 and (NH4)2S2O8 as a dopant and an oxidant, respectively (see Figure). The Cu2O template can be used to prepare different morphologies of PANI (e.g., hollow octahedrons and spheres). Compared with other conventional…
Collagen is the most abundant protein in animals. The protein consists of a helix of three strands, each with sequence X-Y-Gly. Natural collagen is most stable when X is (2S)-proline (Pro) and Y is (2S,4R)-4-hydroxyproline (4R-Hyp). We had shown previously that triple helices in which X is (2S,4S)-4-fluoroproline (4S-…
The diatom microflora collected from glacial lakes, peat-bogs, springs, streams, rivers and wetlands on 352 localities on Shara Mountain and 124 localities on Nidze Mountain, Macedonia, was investigated between 1995 and 2003. A total of 418 taxa from 76 genera, were identified. The taxa are predominantly oligotrophic…
Nanowires of different nature have been shown to self-assemble as a function of stress at the contact between two macroscopic metallic leads. Here we demonstrate for gold wires that the balance between various metastable nanowire configurations is influenced by the microstructure of the starting materials and we disco…
First principles calculations of the geometric and electronic structures have been performed for two coverages (0.25 ML and 0.5 ML) of C on Ni(001) to understand the mechanism of the Ni(001) reconstruction induced by carbon adsorption. The calculated structural behavior of the system is in a good agreement with experi…
Isotropic-Nematic and Nematic-Nematic transitions from a homogeneous base state of a suspension of high aspect ratio, rod-like magnetic particles are studied for both Maier-Saupe and the Onsager excluded volume potentials. A combination of classical linear stability and asymptotic analyses provides insight into possib…