Chemo- and regioselective nitration of geranylacetone by NaNO2/AcOH. Synthesis of 6,10-dimethyl-9-methyleneundec-5E-en-2-one

Treatment of geranylacetone with NaNO₂ in AcOH affords 6,10-dimethyl-9-nitroundeca-5E,10-dien-2-one as the major product. This product was used to synthesize 6,10-dimethyl-9-methyleneundec-5E-en-2-one, a component of the essential oil from the roots of theSaussurea lappa plant. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1299–1302, July, 1999.     

Local Anomalous Sound Field Zones in Shallow Water: Experiment and Simulation

Acoustical Physics - The paper studies experimentally and theoretically the interference structure of the low-frequency spatial amplitude and phase responses of the scalar field and three...     

Spectral properties of helical turbulence

The spectral properties of homogeneous stationary turbulence excited by a force that introduces considerable helicity, along with energy, into the flow are considered. It is shown that helicity is transferred on the inertial range as a passive admixture and its spectrum obeys the “−5/3” law much more accurately than the velocity fluctuation spectrum. The helicity is dissipated on the same scales as the energy, though the helicity transfer dynamics on the inertial range are different on the large and small scales. Numerical experiments are performed on the basis of a cascade model developed for describing helical turbulence.     

An analytic method in general relativity

An analytic method, which Wu called the “Bochner technique,” has been used for fifty years to describe global Riemannian and Kähler geometries. We use this method to describe conformally Killing vector fields and harmonic timelike vector fields on a Lorentzian manifold and to study hydrodynamic models of the Universe, the existence of closed spacelike sections, and the possibility of fibering Lorentzian manifolds.     

Syntheses based on dimethylpyrazoles. 8. Reaction of 3,4- and 4,5-diaminopyrazoles with 4-nitronaphthalic anhydride

Mono- and diacylation products were obtained in the reaction of 3,4-diamino-1,5- dimethylpyrazole with 4-nitronaphthalic anhydride in acetic acid; the monoacylation products do not undergo cyclization even in polyphosphoric acid (PPA). The reaction of 4,5-diamino-1-methylpyrazole under similar conditions gives 2-(5-aminol-1-methyl-4- pyrazolyl)-7-nitrobenzo[d,e]isoquinoline-1,3-(1H,3H)dione, during heating of which in polyphosphoric acid ethyl ester only mono- and diethylation at the amino group occurs.See [1] for communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1090–1094, August, 1985.     

Stepwise fatigue crack propagation in polyethylene resins of different molecular structure

Stepwise fatigue crack propagation in a range of polyethylene resins, some of which are candidates for use in pipes for natural gas distribution, was studied. Examination of the effect of molding conditions on fatigue crack propagation in a pipe resin indicated that fast cooling under pressure produced specimens with the same crack resistance as specimens taken from a pipe extruded from this resin. The mechanism of stepwise crack propagation in fatigue was the same as reported previously for creep loading. Observations of the region ahead of the arrested crack revealed a complex damage zone that consisted of a thick membrane at the crack tip followed by a main craze with subsidiary shear crazes that emerged from the crack tip at an angle to the main craze. The effects of molecular parameters, such as molecular weight, comonomer content, and branch distribution, on the kinetics of fatigue crack propagation were examined. Correlation of creep and fatigue crack resistance made it possible to relate fatigue fracture toughness to molecular parameters by invoking concepts of craze fibril stability developed for creep. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2355–2369, 1998     

New 1-(2-chloroquinolin-3-yl)-4-dimethylamino-2-(naphthalen-1-yl)-1-phenylbutan-2-ols with antituberculosis activity

Russian Chemical Bulletin - New 4-dimethylamino-2-(naphthalen-1-yl)-1-phenyl-1-(quinolin-3-yl)butan-2-ols with antituberculosis activity were synthesized....     

Interpreting the vibrational spectra of uracil molecules and their deuterated isotopomers using a scaled quantum-chemical quadratic force field

The quadratic force field of the uracil molecule is obtained by MP2(full) calculations using the cc-pVTZ and cc-pVQZ basis sets. Under the assumption that the most stable diketone form of the uracil molecule has a flat configuration with C _s symmetry, the available vibrational gas-phase spectra of uracil and the matrix isolation spectra of its seven N-, C-, and mixed N,C-deuterated derivatives are analyzed jointly for the first time by using Pulay??s force field scaling. Band assignments suggested earlier are corrected. It is shown that sets of 14 scaling factors allow us to reproduce the adjusted interpretation of the spectra and to obtain the most reliable quadratic force constant matrix for uracil among those available, based on joint consideration of the experimental and quantum-chemical calculation results.