Effective gel for gold nanoparticle formation, support and metal oxide templating

Gold nanoparticles were synthesized using agarose as a reducing agent, which gelled to support the gold nanoparticles, then readily functioned as a template to produce a porous, evenly-distributed Au/TiO(2) nano-hybrid.     

A complete classification of the flag-transitive affine planes of order 125

The flag-transitive affine planes of order 125 are completely classified. There are five such planes. © 1997 John Wiley & Sons, Inc.     

Phase-oriented surface segregation in an aluminium casting alloy

There have been many reports of the surface segregation of minor elements, especially Mg, into surface layers and oxide films on the surface of Al alloys. LM6 casting alloy (Al-12%Si) represents a challenging system to examine such segregation as the alloy features a particularly inhomogeneous phase structure. The very low but mobile Mg content (approximately 0.001 wt.%), and the surface segregation of modifiers such as Na, mean the surface composition responds in a complex manner to thermal treatment conditions. X-ray photoelectron spectroscopy (XPS) has been used to determine the distribution of these elements within the oxide film. Further investigation by dynamic secondary ion mass spectrometry (DSIMS) confirmed a strong alignment of segregated Na and Mg into distinct phases of the structure.     

Mathematical models for motion of the rear ends of vehicles

A new treatment of the path of the rear wheels of single and multiple axle vehicles produces simple first order differential equations for the motion of the rear wheels relative to the front wheels. We show for the first time, under the assumption of no slipping, that the path of the rear wheels depends only on the path of the front wheels and not on the vehicle speed. We examine motion along straight, circular and winding roads, giving closed form solutions in the first two cases. We also provide a straightforward algorithm for computing vehicle offtracking for any road geometry. We believe these results will be of significant benefit to road designers.     

Chemi-luminescence measurements of hyperthermal Xe+/Xe2+ + NH3 reactions

Luminescence spectra are recorded for the reactions of Xe(+) + NH(3) and Xe(2+) + NH(3) at energies ranging from 11.5 to 206 eV in the center-of-mass (E(cm)) frame. Intense features of the luminescence spectra are attributed to the NH (A (3)Π(i)-X (3)Σ(-)), hydrogen Balmer series, and Xe I emission observable for both primary ions. Evidence for charge transfer products is only found through Xe I emission for both primary ions and NH(+) emission for Xe(2+) primary ions. For both primary ions, the absolute NH (A-X) cross section increases with collision energy before leveling off at a constant value, approximately 9 × 10(-18) cm(2), at about 50 eV while H-α emission increases linearly with collision energy. The nascent NH (A) populations derived from the spectral analysis are found to be independent of collision energy and have a constant rotational temperature of 4200 K.     

Photoelectron spectra and structures of three cyclic dipeptides: PhePhe, TyrPro, and HisGly

We have investigated the electronic structure of three cyclic dipeptides: cyclo(Histidyl-Glycyl) (cHisGly), cyclo(Tyrosyl-Prolyl) (cTyrPro), and cyclo(Phenylalanyl-Phenylalanyl) (cPhePhe) in the vapor phase, by means of photoemission spectroscopy and theoretical modeling. The last compound was evaporated from the solid linear dipeptide, but cyclised, losing water to form cPhePhe in the gas phase. The results are compared with our previous studies of three other cyclopeptides. Experimental valence and core level spectra have been interpreted in the light of calculations to identify the basic chemical properties associated with the central diketopiperazine ring, and with the additional functional groups. The valence spectra are generally characterized by a restricted set of outer valence orbitals separated by a gap from most other valence orbitals. The theoretically simulated core and valence spectra of all three cyclic dipeptides agree reasonably well with the experimental spectra. The central ring and the side chains act as independent chromophores whose spectra do not influence one another, except for prolyl dipeptides, where the pyrrole ring is fused with the central ring. In this case, significant changes in the valence and core level spectra were observed, and explained by stronger hybridization of the valence orbitals.     

Photoelectron spectra of some antibiotic building blocks: 2-azetidinone and thiazolidine-carboxylic Acid

X-ray photoelectron spectra of the core and valence levels of the fundamental building blocks of β-lactam antibiotics have been investigated and compared with theoretical calculations. The spectra of the compounds 2-azetidinone and the 2- and 4-isomers of thiazolidine-carboxylic acid are interpreted in the light of theoretical calculations. The spectra of the two isomers of thiazolidine-carboxylic acid are rather similar, as expected, but show clear effects due to isomerization. Both isomers are analogues of proline, which is well-known to populate several low energy conformers in the gas phase. We have investigated the low energy conformers of thiazolidine-4-carboxylic acid theoretically in more detail and find some spectroscopic evidence that multiple conformers may be present. The measured valence levels are assigned for all three compounds, and the character of the frontier orbitals is identified and analyzed.     

Fuzzy subgroups of n-ary subgroups

We introduce a notion of t-fuzzy n-ary subgroup in an n-ary group (G, f) and have studied their related properties.     

Thermal decomposition of anomeric glycopyranosides

Thermal analysis studies coupled with chemical studies indicate that glycopyranosides undergo thermal decomposition in two overlapping stages. The initial reaction of the glycosides at temperature between 200 and 300°C is cleavage and volatilization of the glycosidic group as the corresponding alcohol, followed by intra- or inter-molecular condensation of the glycosyl portion of the molecule. At higher temperatures (310–340°C) the major reaction is fragmentation of the carbohydrate into a variety of low molecular-weight compounds. Studies with a series of anomeric methyl and phenyl glycosides indicate that, with the methyl and phenyl glycosides, the rate of the low-temperature condensation reaction was dependent on anomeric configuration of the starting glycoside.