Materials Literature
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The synthesis of a dendrimer based on melamine that displays multiple copies of four orthogonally reactive groups, three on the surface and one on the interior, is described. The three groups on the surface are nucleophilic and include four free hydroxyl groups, four hydroxyl groups masked as tert-butyldiphenylsilyl (…
We report the observation of slow emission bands overlapped with the near-band-edge steady-state luminescence of nominally undoped ZnO crystals. At low temperatures the time-resolved spectra are dominated by the emission of several high-energy bound exciton lines and the two-electron satellite spectral region. Further…
A comparison of the field emission properties of exposed nanotubes lying on a tipped carbon nanorope, with the emission properties from a sharpened iron tip of similar dimensions is performed. By varying the electrode separation it is observed that the threshold field for emission for both structures decreases as the…
Abstract Mechanically reinforced and thermally enhanced smectite/epoxy nanocomposites were synthesized using “direct” (without solvent) and “solvent” processing techniques. The molecular dispersion of smectite clay in the epoxy resin was investigated for its role in the rheology, structure formation, and properties of…
The optical property and the molecular packing structure of achiral bent-rod-shaped liquid crystalline compound 1 possessing an amide group and a flexible spacer were investigated by polarized optical microscopy (POM), circular dichroism (CD) spectroscopy, and X-ray diffraction (XRD). The molecules generated highly or…
The temperature, frequency, and orientation dependence of complex electrical permittivity in 0.9Pb(Mg1∕3Nb2∕3)O3-0.1PbTiO3 (0.9PMN-0.1PT) unpoled single crystals have been investigated in detail. The spontaneous ferroelectric-to-relaxor (FE-R) phase transition was observed in 0.9PMN-0.1PT crystals at about 280K. Inter…
Mechanical oscillatory behavior of multiwalled carbon-nanotube-based oscillators is investigated using molecular-dynamics simulations. The second-generation reactive bond-order potential and a Morse-type van der Waals potential based on the local-density approximation are used to describe bonding and nonbonding atomic…
Using both laser-excited fluorescence and optical absorption methods, we have determined 57 crystal-field (CF) energy levels of Sm 3+ in crystals of Sm(Et2Dtc)3(bipy). The analysis of the energy levels is based on a model Hamiltonian consisting of both free-ion and CF terms. The CF modeling of the experimental energy…
Recombination dynamics of photoluminescence (PL) in colloidal CdSe/ZnS quantum dots (QDs) were studied using time-resolved PL measurements. The PL intensity shows a biexponential decay at 9 K, consisting of a fast component (~1 ns) and a slow component (~6.3 ns). Based on the emission-energy and temperature dependence…
The specific heat of an aligned bulk multiwalled carbon nanotube sample made by the chemical vapour deposition method was measured from 250 to 1.8 K. The specific heat curve gradually decreased, showing one-dimensional (1D) behaviour down to 40 K. Below 40 K it showed a rapid decrease due to the dimensional change fro…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTExfoliation of Montmorillonite Clay by Mannich Polyamines with Multiple Quaternary SaltsChien-Chia Chu, Ming-Li Chiang, Chung-Min Tsai, and Jiang-Jen LinView Author Information Department of Chemical Engineering, National Chung Hsin…
Wurtzite ZnS, a high-temperature polymorph of ZnS, was prepared by a novel low-temperature and mild solvothermal process over a temperature range of 160−200 °C. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high r…
The evolution of PbTe with pressure has been reexamined using synchrotron x-ray diffraction. The phase transition at 6 GPa is not to the GeS (B16) or TlI (B33) type structures, as previously reported, but to an orthorhombic $Pnma$ structure, with cell parameters $a=8.157(1)$, $b=4.492(1)$, and $c=6.294(1)\mathrm{\AA{}…
Pyridoxal kinase (PDXK) catalyzes the phosphorylation of pyridoxal, pyridoxamine, and pyridoxine in the presence of ATP and Zn2+. This constitutes an essential step in the synthesis of pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, a cofactor for over 140 enzymes. (R)-Roscovitine (CYC202, Seliciclib) is…
Single-crystalline metallic nanowires, Ni, Ag, and Zn, were successfully fabricated using an anodic aluminium oxide (AAO) template by electro-deposition. The single-crystalline Ni and Ag nanowires showed face-centred cubic (fcc) structure with a preferred orientation along the [220] direction. Zn nanowires with hexago…
Abstract Silica nanoparticles having different sizes were obtained by the sol‐gel process and characterized. The prepared nanoparticles were subsequently used as reinforcing fillers to prepare epoxy‐based composites with a silica content ranging from 1 to 5 wt %. SEM analysis and tensile tests carried out on the silic…
We study the coarsening dynamics of two-dimensional hexagonal patterns formed by single microdomain layers of block copolymers, using numerical simulations. Our study is focused on the temporal evolution of the orientational correlation length, the interactions between topological defects, and the mechanisms of coarse…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTBistable Photoswitching in the Film of Fluorescent Photochromic Polymer: Enhanced Fluorescence Emission and Its High Contrast SwitchingSeon-Jeong Lim, Byeong-Kwan An, and Soo Young ParkView Author Information School of Materials Sci…
Anhydrous ammonia is a widely used N fertilizer and its interactions with soils and soil clays play an important role in its environmental fate. This study was conducted to determine the quantity and forms of ammonia adsorbed by clay‐sized fractions of soils as a function of water content, exchangeable cation, and org…
The electronic band structures of orthorhombic (oP28) and monoclinic (mC28) $\mathrm{Mn}{\mathrm{Sb}}_{2}{\mathrm{S}}_{4}$ were investigated with ab initio calculations in the local spin density approximation to the density functional theory. An analysis of the electronic properties and of the chemical bonding is prov…