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Abstract Organic photochromic systems represent a starting point for the elaboration of light‐triggered molecular switching devices. The novel bispyridinium and bispyridine compounds 1 2+ and 6 were synthesized as their uncyclized isomers from 3,5‐dibromo‐2‐methylthiophene in overall yields of 43 and 44%, respectively…
Abstract The elastic modulus E l of the crystalline regions of cellulose polymorphs in the direction parallel to the chain axis was measured by x‐ray diffraction. The E l values of cellulose I, II, III I , III II , and IV I were 138, 88, 87, 58, 75 GPa, respectively. This indicates that the skeletons of these polymorp…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganic Chemistry within Ceramic Matrixes: Doped Sol-Gel MaterialsDavid AvnirCite this: Acc. Chem. Res. 1995, 28, 8, 328–334Publication Date (Print):August 1, 1995Publication History Published online1 May 2002Published inissue 1 August 1995https://doi.org/10.1021/ar00056a002…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDynamic Mechanical Study of the Factors Affecting the Two Glass Transition Behavior of Filled Polymers. Similarities and Differences with Random IonomersGeorge Tsagaropoulos and Adi EisenbergCite this: Macromolecules 1995, 28, 18, 6067–6077Publication Date (Print):August 1,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLayer-by-Layer Self-Assembly of Polyelectrolyte-Semiconductor Nanoparticle Composite FilmsNicholas A. Kotov, Imre Dekany, and Janos H. FendlerCite this: J. Phys. Chem. 1995, 99, 35, 13065–13069Publication Date (Print):August 1, 1995Publication History Published online1 May 2…
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The hydrous ruthenium oxide has been formed by a sol‐gel process. The precursor was obtained by mixing aqueous solutions of RuCl 3 · x H 2 O and alkalis. The hydrous ruthenium oxide powder was obtained by annealing the precursor at low temperatures. The crystalline structure and the electrochemical properties of the p…
This paper presents novel results on the electrical properties of amorphous carbon films prepared by ion-beam sputtering. The conductivity is found to be similar to that seen in evaporated carbon. Over the range approximately 40-300 K, it is well described by the variable range hopping equation with a hopping exponent…
The electron paramagnetic resonance spectrum of Mn 4+ in single-crystal lead titanate has been studied at 9.8 and 33.8 GHz. An axial sextet with g perpendicular to eff =3.7742(1) to g/sub /// eff approximately=2.00 was measured at 9.8 GHz and with g perpendicular to eff =2.7048(15) at 33.8 GHz; a second sextet was obs…
High structural regularity, second-order nonlinear susceptibility, and thermal stability characterize the self-assembled stilbazolium chromophoric multilayers (the structure obtained after the first cycle is shown schematically on the right). A topotactic approach for the stilbazolium chromophore deposition has result…
Enhancement of the phonon density of states due to low-energy floppy modes in crystalline and glassy states of the high-temperature ceramic S${\mathrm{i}}_{3}$${\mathrm{N}}_{4}$ is investigated using the molecular-dynamics method. Floppy modes appear continuously in the glass as the connectivity of the system is reduc…
CuxS nanocrystals (NC’s) are reported. The samples are prepared by a CdS-to-CuxS chemical conversion from the glasses originally containing CdS NC’s. A room-temperature linear absorption of the converted samples shows several well resolved peaks with spectral positions from red to blue. These spectral features are exp…
Thin film ferroelectrics with polarization gradients normal to the growth surface readily form when gradients in temperature, strain, or composition are coupled to the polarization vector in ferroelectric materials. This letter describes the formation of thin films of potassium tantalum niobate with graded polarizatio…
Extremely stiff macromolecules in the form of “hairy rods” or more precisely “molecular bottlebrushes” (without a handle) are easily accessible by the polymerization of polymacromonomers. As anticipated from their high degree of stiffness, these molecules form lyotropic, liquid‐crystalline phases, although they consis…
Cyclic tetrameric units (··Mn-NC-Fe-CN··)4 (depicted on the right) construct the two-dimensional network of the title compound. The layers thus formed are linked together by van der Waals contacts. The compound displays metamagnetism: ferromagnetic coupling is observed within layers and antiferromagnetic coupling betw…
π-Stacking interactions between adjacent aromatic ligand fragments of L− separated by approximately 3.4 Å provides a pathway for weak ferromagnetic coupling in the tetramer [Mn4L4](PF6)4 (1). The cavity of L− is too large for a single MnII ion; instead the tetramer 1 comprises a Mn4 tetrahedron, with a ligand L− attac…
An air bubble trapped in water by an oscillating acoustic field undergoes either spherical or nonspherical pulsations depending on the strength of the forcing pressure. Two different instability mechanisms (the Rayleigh-Taylor instability and parametric instability) cause deviations from sphericity. Distinguishing the…
Novel, polymeric linear chains of Keggin polyoxometalate units PMnW11O39 linked through Mn-O-W bridges (see picture below) are present in the structure of the title compound 1. The chains alternate with layers of the organic donor bis(ethylenedithio)tetrathiafulvalene (ET). Compound 1 promises interesting material pro…
Viscometry and dynamic light scattering (DLS) were used to study suspensions of colloidal particles which interact like hard spheres. The rate of ``structural relaxation'' of microscopic density fluctuations, indicated by the long-time diffusion coefficient measured by DLS at the peak of the static structure factor, w…
We have measured Raman spectra of diamond with nanometer size, called cluster diamond. The Raman bands assigned to sp2 and sp3 clusters have been observed at around 1600 and 1322 cm−1, respectively. This result suggests that the cluster diamond slightly contains the sp2 cluster. The Raman band assigned to sp3 cluster…