A relativistic quantum dynamical model based on the classical string

Motivated by geometrical considerations of the string model, we construct a dynamical theory of composite particles that is Poincaré invariant in four dimensions, with no tachyons and no ghosts. The resulting physical states lie on indefinitely rising trajectories.     

A test theory of special relativity: II. First order tests

First-order tests of special relativity are based on a comparison of clocks synchronized with the help of slow clock transport with those synchronized by the Einstein procedure. This comparison enables the measurement of the one-way velocity of light and is equivalent to a measurement of the time dilatation factor. The accuracy of present measurements is of the order 10^–7, yielding an upper limit of 3 cm/sec for the ether drift.     

Tribromo Phloroglucinol as a Novel and Highly Efficient Reagent for the Conversion of Benzothioamides to the Corresponding 1,2,4-Thiadiazoles

2,4,6-Tribromo-1,3,5-trihydroxybenzene (TBTHB) as a reagent was efficiently reacted with 6 molar equivalents of benzothioamides in dimethyl sulfoxide (DMSO), and the corresponding 3,5-diaryl-1,2,4-thiadiazoles were obtained in almost quantitative yields (91–98%) and in short times (15–20 min) with the formation of hexahydroxybenzene as a rather valuable by-product.     

Simulations of docking C60 in β-Cyclodextrin

We simulated the docking of the fullerene C₆₀ in β-Cyclodextrin using two models. We considered in this study complexes formed by 1:1 and 1:2 guest-host stoichiometries in vacuum and aqueous phase. We investigated three orientations for β-CDs in 1:2 complexes, Head to Head (HH), Head to Tail (HT) and Tail to Tail (TT). Both models agree on energetic of the inclusion process, optimum 3D structure complex, inclusion mode and stoichiometry of most stable structure. In both media, we predicted the possibility of formation of 1:1 complexes, where the most stable structure corresponds to the location of C₆₀ at the wider rim of β-CD with a partial inclusion. In vacuum, for 1:2 stoichiometry, the most stable complex was in HH orientation with a “V” shaped structure which favored some intermolecular hydrogen bonds, but in water both TT and HH orientations were equally stable within the calculations errors. Over all, we found that the complex with 1:2 stoichiometry is more stable than that with 1:1 stoichiometry. Our results are in agreement with the experimental spectroscopic data. We found that the driving forces for complexation in both environments were non bonded Van der Waals interaction between the host and the guest molecule for both stoichiometries. Also, we noticed that the presence of water molecules caused a relative destabilization of all complexes in both stoichiometries except for TT orientation.     

Gauge conditions in dual resonance models

Simplifying the arguments of Chang and Mansouri, we show that the Virasoro conditions in dual resonance models are related to geometrical and mechanical properties of classical two-dimensional media.     

Emission of gases and degradation volatiles from polymeric wood constituents in friction welding of wood dowels

Analysis of volatile compounds and gases emitted as smoke at the welding interface during rotational wood dowel welding of a hardwood (beech) and of a softwood (Norway spruce) has shown that the compounds in such a smoke are water vapour, CO₂, degradation compounds from wood polymeric carbohydrates and from amorphous lignin, as well as some volatile terpenes, these latter only for the softwood used, Norway spruce. The main carbohydrates contributing to the volatile compounds are xylans for beech and glucomannans for spruce. Numerous compounds, in very small proportions derived from the degradation and rearrangement reactions of lignin, have also been identified. The proportion of CO₂ emitted is very low, and neither CO nor methane is emitted due to the relatively low temperature of dowel welding. Experiments at temperature slightly higher than that of dowel welding but prolonged in time have shown that the main component of the smoke produced during welding appears to be water vapour.