Dish or plaque

Glass, Islamic, Abbasid; 2 61/64 in.x 1 3/16 in.; mosaic glass

Fabrication of SiGe rings and holes on Si(001) by flash annealing

We show that SiGe islands are transformed into nanoholes and rings by annealing treatments only and without Si capping. Rings are produced by a rapid flash heating at temperatures higher than the melting point of Ge, whereas nanoholes are produced by several minute annealing. The rings are markedly rich in Si with respect to the pristine islands, suggesting that the evolution path from islands to rings is driven by the selective dissolution of Ge occurring at high temperature.

Measurement of Large Dipolar Couplings of a Liquid Crystal with Terminal Phenyl Rings and Estimation of the Order Parameters

NMR spectroscopy is a powerful means of studying liquid-crystalline systems at atomic resolutions. Of the many parameters that can provide information on the dynamics and order of the systems, H-1-C-13 dipolar couplings are an important means of obtaining such information. Depending on the details of the molecular structure and the magnitude of the order parameters, the dipolar couplings can vary over a wide range of values. Thus the method employed to estimate the dipolar couplings should be capable of estimating both large and small dipolar couplings at the same time. For this purpose, we consider here a two-dimensional NMR experiment that works similar to the insensitive nuclei enhanced by polarization transfer (INEPT) experiment in solution. With the incorporation of a modification proposed earlier for experiments with low radio frequency power, the scheme is observed to enable a wide range of dipolar couplings to be estimated at the same time. We utilized this approach to obtain dipolar couplings in a liquid crystal with phenyl rings attached to either end of the molecule, and estimated its local order parameters.

Efficiently producing single-walled carbon nanotube rings and investigation of their field emission properties

Single-walled carbon nanotube (SWNT) rings with a diameter of about 100 nm have been prepared by thermally decomposing hydrocarbon in a floating catalyst system. These rings appeared to consist mostly of SWNT toroids. High resolution transmission electron microscopy showed that these rings were composed of tens of SWNTs with a tightly packed arrangement. The production of SWNT rings was improved through optimizing various growth parameters, such as growth temperature, sublimation temperature of the catalyst, different gas flows and different catalyst components. The growth mechanism of the SWNT rings is discussed. In the field emission measurements we found that field emission from a halved ring is better than that from a whole SWNT ring, which contributed to the better emission from two opened ends of the nanotubes of the halved SWNT ring.

Self-Assembly of Hyperbranched Multiarmed PEG-PEI-PLys(Z) Copolymer into Micelles, Rings, and Vesicles

Self-assembling of synthesized novel biodegradable hyperbranched amphiphilic poly(ethylene glycol)-polyethylenimine-poly(epsilon-benzyloxycarbonyl-L-lysine) (PEG-PEI-PLys(Z)) in aqueous media is studied. In aqueous media. PLys(Z) is the hydrophobic segment, with PEG and PEI as the hydrophilic segments. It will self-assemble into spherical shape when the selected solvent water is dropped into the common solvent tetrahydrofuran (THF). And when PEG-PEI-PLYS in common solvent is dropped into mixed solvent water and THF, rings will come into King. The spherical and rings are observed by environmental scanning electron microscopy (ESEM) and transmission electron microscopy ITEM). It shows that the size of the sphere is about 100 nm, and the diameter of ring distributes from 400 nm to 10 mu m and bigger with the time roll around.

The Lord of the Rings and ?Identification?: A Critical Encounter

Barker, M. (2005) 'The Lord of the Rings and 'identification': a critical encounter', European Journal of Communication, 20, 3, 353-378 Sponsorship: This research was made possible by a grant from the Economic and Social Research Council (ESRC Grant No. 000-22-0323)

Structural manifestation of the delocalization error of density functional approximations: C(4N+2) rings and C(20) bowl, cage, and ring isomers.

The ground state structure of C(4N+2) rings is believed to exhibit a geometric transition from angle alternation (N < or = 2) to bond alternation (N > 2). All previous density functional theory (DFT) studies on these molecules have failed to reproduce this behavior by predicting either that the transition occurs at too large a ring size, or that the transition leads to a higher symmetry cumulene. Employing the recently proposed perspective of delocalization error within DFT we rationalize this failure of common density functional approximations (DFAs) and present calculations with the rCAM-B3LYP exchange-correlation functional that show an angle-to-bond-alternation transition between C(10) and C(14). The behavior exemplified here manifests itself more generally as the well known tendency of DFAs to bias toward delocalized electron distributions as favored by Huckel aromaticity, of which the C(4N+2) rings provide a quintessential example. Additional examples are the relative energies of the C(20) bowl, cage, and ring isomers; we show that the results from functionals with minimal delocalization error are in good agreement with CCSD(T) results, in contrast to other commonly used DFAs. An unbiased DFT treatment of electron delocalization is a key for reliable prediction of relative stability and hence the structures of complex molecules where many structure stabilization mechanisms exist.

Density functional and Monte Carlo studies of sulfur. I. Structure and bonding in S-n rings and chains (n=2-18) (vol 118, pg 9257, 2003)

Density functional calculations have been performed for ring isomers of sulfur with up to 18 atoms, and for chains with up to ten atoms. There are many isomers of both types, and the calculations predict the existence of new forms. Larger rings and chains are very flexible, with numerous local energy minima. Apart from a small, but consistent overestimate in the bond lengths, the results reproduce experimental structures where known. Calculations are also performed on the energy surfaces of S8 rings, on the interaction between a pair of such rings, and the reaction between one S8 ring and the triplet diradical S8 chain. The results for potential energies, vibrational frequencies, and reaction mechanisms in sulfur rings and chains provide essential ingredients for Monte Carlo simulations of the liquid–liquid phase transition. The results of these simulations will be presented in Part II.