Electronic structures and electrophilic substitution in 2-(4-R-2-quinolyl)thiophenes and 5-(4-R-2-quinolyl)-2,2′-dithienyls

The electronic structures and reactivity indexes (RI) of 2-(4-R-2-quinolyl)thiophenes and 5-(4-R-2-quinolyl)-2,2-dithienyls (R = H, COOH, COOC₂H₅, and NHCOCH₃) and their protonated forms were calculated by the Pariser-Parr-Pople (PPP) method. The peculiarities of the geometrical and -electron structures were established. The calculated reactivity indexes are compared with experimental data on the electrophilic substitution reactions of the investigated compounds. A qualitative agreement between the calculated values and the experimental data was established. It is shown that quinoline derivatives of thiophene are less reactive than the corresponding dithienyl compounds in electrophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 751–754, June, 1979.     

Synthesis of some nitrogen derivatives of the thiophene analog of cinchophen

2-Nitro-5-(4-carboxy-2-quinolyl)thiophene was obtained bynitration of 5-(4-carboxy-2-quinolyl) thiophene. Data from microbiological tests of the nitro-substituted thiophene and its carboxyl-group derivatives are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 183–184, February, 1973.     

Research on some condensation products in the 2, 2′-dithienyl series II

Crotonoid condensation of 5-formyl-2,2′-dithienyl with some aromatic and heterocyclic ketones in alkaline medium is used to synthesize a number of hitherto undescribed α,β unsaturated ketones of the 2,2′-dithienyl series. All the compounds investigated give intensely colored halochromic solutions in sulfuric acid.     

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Dynamic yield-strength determination at elevated temperatures after nanosecond pulse heating

An experimental method is described that has been used to determine the yield strength of 6061-T6 aluminum after extremely short times at elevated temperature. The method combines electron-beam pulse heating and onedimensional stress-wave loading. A 3.5-MeV pulsed electron-beam source (pulse width of 70 nanoseconds) is used to deposit energy uniformly through the thickness and along a limited region of a slender aluminum rod. An axial compressive stress wave, produced by projectile impact on one end of the rod, propagates into the heated region a few microseconds after energy deposition. The nanosecond electron-beam pulse increases the internal energy of the material before it can expand to equilibrium dimensions at the elevated temperature. Additional time is therefore required for the specimen to equilibrate mechanically through the propagation of radial release waves which originate at the stress-free boundary of the sample. The deformation produced by these radial relief waves is coupled with microstructural changes that also contribute to a reduction in the yield strength of the material at elevated temperature, as well as at room temperature following electron-beam heating.     

How to search for pentaquarks in high energy hadronic interactions

The strange-anticharmed Pentaquark is a uudc?s or uddc?s five-quark baryon that is expected to be either a narrow resonance, or possibly even stable against strong and electromagnetic decay. We describe this hyperon here, its structure, binding energy and lifetime, resonance width, production mechanisms, production cross sections, and decay modes. We describe techniques to reduce backgrounds in search experiments and to optimize the conditions for Pentaquark observation. Possibilities for enhancing the signal over background in Pentaquark searches are investgated by examining predictions for detailed momentum and angular distributions in multiparticle final states. We consider a loosely bound molecule and also a strongly-bound five-quark system. Fermilab E791 data, currently being analyzed, may have marginal statistics for showing definitive signals. Future experiments in the spirit of the recent CHARM2000 workshop, such as FNAL E781 and CERN COMPASS with 10⁶?10⁷ reconstructed charmed baryon events, should have sensitivity to determine whether or not the Pentaquark exists.