Materials Literature
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For 40 million years, diatoms have dominated the reverse weathering of silica on Earth. These photosynthetic protists take up dissolved silicic acid from the water and precipitate opaline silica to form their cell wall. We show that the biosilica of diatoms is an effective pH buffer, enabling the enzymatic conversion…
The results of the X-ray, microscopic, magnetic, and dielectric measurements performed for PFN single crystals and ceramic samples are presented. The influence of the technological conditions on selected physical properties of the materials examined is shown.
Ultrananocrystalline diamond (UNCD) thin films consist of 2–5 nm grains of pure sp3-bonded carbon and ∼0.5-nm-wide grain boundaries with a disordered mixture of sp2- and sp3-bonded carbon. UNCD exhibits many interesting materials properties that are a direct consequence of its nanoscale morphology. In this work, we re…
Individual paramagnetic defect centers in diamond nanocrystals have been investigated by low-temperature high-resolution optical spectroscopy. Narrow fluorescence excitation spectral lines have been found, indicating transitions between individual spin sublevels. Spectral diffusion is explained by cross relaxation amo…
Diamond possesses extraordinary material properties, a result that has given rise to a broad range of scientific and technological applications. This study reports the successful production of high-quality single-crystal diamond with microwave plasma chemical vapor deposition (MPCVD) techniques. The diamond single cry…
A small library of copper and noble metal nanoclusters is designed and synthesized. These clusters are tested as catalysts in the Suzuki cross-coupling of various aryl halides with phenylboronic acid. It is found that copper and copper/noble metal combination nanoclusters are active catalysts for this reaction, the mo…
In particle formation, the method can be just as important as the chemical reaction involved. A new method of synthesizing hydrotalcite-like layered double hydroxides (LDHs) of the type [Mg 1 - x Al x (OH) 2 ] x + (CO 3 2 - ) x/ 2 · y H 2 O ( x = 1.7−3.3) is reported. The key features of this method are a very rapid m…
The photophysical properties of the lowest singlet and triplet excited states of some trans-1-(9-anthryl)-2-(n-naphthyl)ethenes (n = 1 or 2, t-n-ANE) and trans-1-(9-anthryl)-2-(n-quinolyl)ethenes (n = 2–4, t-n-AQE) derivatives have been studied in methylcyclohexane and acetonitrile at room temperature. The hydrocarbon…
Abstract Atactic and syndiotactic‐rich poly(vinyl alcohol) fibers were prepared by gel spinning using ethylene glycol as a solvent. The mechanical properties of the fibers were independent of the degree of polymerization, although they were dependent on syndiotacticity. The amounts of tie molecules and the difference…
Abstract Blend membranes of chitin/cellulose from 12 : 50 to 12 : 250 were successfully prepared from cotton linters in 1.5 M NaOH/0.65 M thirourea solution system. Two coagulation systems were used to compare with each other, one coagulating by 5 wt % H 2 SO 4 (system H), and the other by 5 wt % CaCl 2 and then 5 wt…
Modification of isotactic polypropylene (iPP) film was carried out by grafting of acrylic acid (AA) onto its backbone using supercritical (SC) CO2 as a solvent and swelling agent. The iPP film was impregnated with the monomer AA and benzoyl peroxide initiator using SC CO2 at 308.15 K, followed by thermal polymerizatio…
The structural reorganization of carbon nanoparticles into single-wall nanotubes via high temperature annealing in absence of metal catalysts, was monitored by photoemission and x-ray absorption spectroscopy. It has been found that for this system an advanced graphitization process is made possible by the peculiar nan…
Heat capacity of a halogen-bridged quasi-one-dimensional mixed-valence binuclear metal complex (the so-called $\mathrm{MMX}$ chain), ${\mathrm{Pt}}_{2}(n\ensuremath{-}\mathrm{Bu}{\mathrm{CS}}_{2}{)}_{4}\mathrm{I},$ was measured by adiabatic calorimetry. First-order phase transitions were observed at 213.5 K and 323.5…
This paper considers the theory of electron field emission from nanoscale emitters with particular focus on thermal and electrical energy transport. The foundational theory of field emission is explored, and a model is presented that accounts explicitly for the energy band curvature produced by nanoscale tip emitters.…
An unconventional self-assembly process was integrated with traditional silicon microfabrication technologies to directly form hexagonally ordered nanoporous patterns on both SiO 2 and Si surfaces. Starting with an aluminium thin film deposited on a SiO 2 or Si substrate, an Al anodization process was employed to gene…
Abstract Comonomer effect on the mechanical and morphological behavior of the calcite (stearic acid coated calcium carbonate)‐filled polypropylene (PP), poly(propylene‐random‐ethylene) copolymer (CoPP), and poly(propylene‐ co ‐ethylene‐ co ‐1‐butene) terpolymer (TerPP) composites were investigated by using dumbbell ba…
The crystal structure of a new polymorph of nabumetone has been determined that displays dramatically lower stability yet differs only in weak intermolecular interactions from the known form.
The electronic eigenvalues and eigenstates of finite parts of Penrose structures are studied on the basis of a recently proposed three-dimensional solvable model [J. Phys. A 30, 7831 (1997)]. This model allows to take explicitely into account the geometry in three-dimensional space and involves no assumptions such as…
The structure and structural transition of the glycine residue adjacent to the N-terminal alanine residue of the poly(L-alanine), (Ala)(12-13), region in Samia cynthia ricini silk fibroin was studied using (13)C nuclear magnetic resonance (NMR). Most of the glycine carbonyl peaks in the (13)C solution NMR spectrum of…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTGold Nanoparticle Patterns on Polymer Films in the Presence of Poly(amidoamine) Dendrimers†Jongok Won, Kyo Jin Ihn, and Yong Soo KangView Author Information Department of Applied Chemistry, Sejong University, 98 Gunja, Gwangjin, Seoul, 143-747, Korea, Department of Chemical Eng…