Materials Literature
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Abstract The crystalline morphologies of PBT (poly butylene terephthalate) and its glass fiber reinforced composite systems were investigated in a thin‐film form by polarized optical microscopy and wide‐angle X‐ray diffraction. Three different types of PBT morphology were identified in the Maltese cross pattern: 45° c…
The passage of a current through a solid requires a pathway for the movement of electrons or holes. A new class of phenalenyl-based neutral radical molecular conductors has recently been reported; a distinctive feature of these molecular solids is the absence of any obvious conducting pathway(s). These radicals do not…
Three S = 1 bis(semiquinone) complexes have been prepared. To ensure ferromagnetic intramolecular exchange coupling, the two semiquinones are attached 1,3 to a 5-substituted phenylene ring. The biradical complexes differ in their meta-substituents: 1-NMe(2)(), X = N,N-dimethylamino; 1-t-Bu, X = tert-butyl; 1-NO(2)(),…
The charge transport in nanoparticulate ZnO layers held at different potentials was studied by analyzing the anodic transient photocurrents. The electrodes used in the electrochemical cell consisted of ZnO films coated onto conductive ITO substrates. In these experiments, three contributions to the photocurrent could…
A single-component conducting molecular crystal composed of paramagnetic copper complexes, [Cu(dmdt)2]0+, was prepared. The crystal has an unprecedented three-dimensionally packed molecular arrangement and exhibits a fairly high conductivity (1 S cm-1 at room temperature). The magnetic susceptibility measurements reve…
We report the first synthesis of a disyndiotactic polymer through topochemical polymerization using di(4-methoxybenzyl)muconate as the 1,3-diene dicarboxylate monomer. It provides a tritactic polymer under photoirradiation in the crystalline state, as a result of the alternate molecular stacking in a column formed in…
The calormetically measured heats of adsorption of Cu, Ag, and Pb on MgO(100), previously measured in our group, are correlated with bulk properties of the metals and their sticking probabilities and film morphologies. The low-coverage heats of adsorption (when the metals are mainly in two-dimensional (2D) islands) ar…
The temperature profile applied during batch cooling crystallization affects the supersaturation level, which in turn affects the crystal size distribution. It is possible, in principle, to calculate the optimal cooling profile; however, the nucleation and growth kinetics are rarely known to the degree of accuracy nec…
Abstract To synthesize an epoxy–montmorillonite nanocomposite, the intercalation of clay layers with acid onium ions {[H 3 N(CH 2 ) n −1 COOH] + , [H 3 N(CH 2 ) n −1 CH 3 ] + , [H 3 N(CH 2 ) − NH 2 ] + , and [H 3 N(CH 2 ) n NH 3 ] 2+ } by different methods were studied. The intercalated clay was characterized by XRD,…
The antimicrobial properties of chitosan, a derivative of chitin, were investigated in the solid and liquid culture against bacteria associated with waterborne disease in order to assess the potential for using chitosan as a natural disinfectant. Six strains which included three gram-negative and three gram-positive b…
High-frequency and high-field electron paramagnetic resonance (HFEPR) spectroscopy (using frequencies of approximately 90-550 GHz and fields up to approximately 15 T) has been used to probe the non-Kramers, S = 1, Ni(2+) ion in a series of pseudotetrahedral complexes of general formula NiL(2)X(2), where L = PPh(3) (Ph…
Highly ordered mesoporous silica can be regenerated from a mesoporous carbon CMK-3 that is a negative replica of mesoporous silica SBA-15, indicating reversible replication between carbon and inorganic materials.
The local electronic structure of N atoms in a diluted GaAs1-xNx (x=3%) alloy, in view of applications in optoelectronics, is determined for the first time using soft-X-ray absorption (SXA) and emission (SXE). Deviations from crystalline GaN, in particular in the conduction band, are dramatic. Employing the orbital ch…
Effect of contact interfaces, between metallic single-wall carbon nanotubes (SWCNT) and external electrodes made also of nanotubes, on the electrical conductance is studied. A tight-binding model with both diagonal and off-diagonal disorder, a recursive Green function technique as well as the Landauer formalism are us…
We synthesize, for the first time, using sol−gel technique and without doping any trivalent impurities, monodispersed, spherical ZrO 2 particles in size range of ∼500−600 nm, exhibiting metastable tetragonal crystal structure at room temperature. It is revealed using high-resolution transmission electron microscopy th…
Due to the complex interplay of magnetic, structural, electronic, and orbital degrees of freedom, biaxial strain is known to play an essential role in the doped manganites. For coherently strained La(2/3)Ca(1/3)MnO(3) thin films grown on SrTiO(3) substrates, we measured the magnetotransport properties both parallel an…
Planar light-emitting diodes (LEDs) fabricated within a single high-mobility quantum well are demonstrated. Our approach leads to a dramatic reduction of radiative lifetime and junction area with respect to conventional vertical LEDs, promising very high-frequency device operation. Devices were fabricated by UV lithog…
Reduction factors (RF), that are needed when modeling vibronic systems by an effective Hamiltonian in an electronic basis, are calculated for the T_1u x h_g Jahn-Teller (JT) system. The results obtained will be useful when modeling the fullerene anion C_60-, which is believed to exhibit a T_1u x h_g JT effect in its g…
Two series of uniaxial tensile tests are performed on isotactic polypropylene with the strain rates ranging from 5 to 200 mm/min. In the first series, injection-molded specimens are used without thermal pre-treatment, whereas in the other series, the samples are annealed for 51 h at 160C prior to testing. A constituti…
Photoluminescence excitation spectroscopy and scanning-tunneling spectroscopy are used to study the electronic states in CdSe quantum rods that manifest a transition from a zero-dimensional to a one-dimensional quantum-confined structure. Both optical and tunneling spectra show that the level structure depends primari…