Measurement of hydrogen- and self-broadened half-widths of ammonia at 200 and 300°K

The hydrogen- and self-broadened half-widths have been measured for the (v₁+v₂)- and (v₂+v₃)-bands of ammonia at 300 and 207°K. Measurement of hydrogen-broadened widths has been restricted to J, K ?6, but that of self-broadened widths is done for a few lines outside that range. Assuming a power-law dependence of half-width on temperature given by γ(T)=γ(T₀)(T/T₀)^α, the average value of the index α for the lines measured is found to be 0·57 for hydrogen broadening.     

The role of higher-multipolar and repulsive forces in the calculation of collision-broadened line-widths of linear molecules

Collision-broadened line widths in CO-CO₂ and CO-O₂ collisions have been calculated by incorporating interactions due to octopoles and hexadecapoles and short range repulsive interactions into Anderson's theory. It is shown how these higher-order interactions can be manipulated to yield good agreement with experimental data. A critical evaluation of this totally empirical manipulation suggests that a thorough revision of the theory is required for all but simple dipole-dipole interactions. In the process of the evaluation, the values of the multipole moments are discussed.     

Oscillatory hydromagnetic disc flow

Summary This paper presents the solution to the problem of determining the flow field and the fluctuating torque necessary to sustain the motion of a torsionally oscillating plate in a viscous conducting fluid subjected to a uniform axial field under the assumptions that the amplitude of the oscillation is small and that the magnetic Prandtl number Pr _m () is small enough to justify the neglect of induced fields. The analysis reveals that the field decreases the flow velocities, but increases the magnitude of the fluctuating torque.     

Theory of coherent,degenerate two-photon absorption and emission

The theory of the coherent, two-photon resonant interaction of a monochromatic field with N atoms is given. It is seen that the dynamics of the atom-field system can be completely determined when the field is “strong”. Two specific examples are given: (i) two-photon absorption by atoms in ground state, and (ii) stimulated two-photon emission by fully excited atoms, assuming a coherent field in both cases. In case (ii), the field shows photon-antibunching after the decay of half of the atoms. The merits of our approach are shown by comparing with other treatments. Our results can also be applied to certain degenerate four-wave mixing processes which are described by a similar Hamiltonian.     

A concise, enantioselective approach to (-)-quinic acid

[reaction: see text] An expedient, enantioselective synthesis of a key precursor to (-)-quinic acid has been achieved from an ephedrine-derived morpholine-dione. The salient features of this approach are a highly diastereoselective conversion of the dione to a dialkenyl morpholinone and a subsequent ring-closing metathesis reaction. Removal of the ephedrine portion generates an enantiomerically enriched hydroxycyclohexene carboxamide that is readily converted to the quinic acid precursor.     

First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

A new organocatalytic system, novel chiral bisformamide and in situ generated L-proline-derived allylsilane reagent , which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.     

Further exploration of antimicrobial ketodihydronicotinic acid derivatives by multiple parallel syntheses

A synthetic reexamination of a series of ketodihydronicotinic acid class antibacterial agents was undertaken in an attempt to improve their therapeutic potential. A convenient new synthesis was developed involving hetero Diels-Alder chemistry producing 74 new analogs in a multiple parallel synthetic manner and these were examined in vitro for their antimicrobial potential. Several compounds demonstrated significant broad-spectrum activity against clinically derived bacterial strains but previously known 1-(2,4-difluorophenyl)-6-(4-dimethylaminophenyl)-4-pyridone-3-carboxylic acid (7) remained the most potent compound in this class. Cross-resistance with ciprofloxacin supported a commonality of mode of action. Permiabilization of Escherichia coli cells by polymyxin B significantly enhanced potency with these agents suggesting that poor cellular uptake was primarily responsible for the disappointing activity against bacteria that some of the analogs exhibited.     

An analysis for heat equations arises in diffusion process using new Yang-Abdel-Aty-Cattani fractional operator

The heat equation is parabolic partial differential equation and occurs in the characterization of diffusion progress. In the present work, a new fractional operator based on the Rabotnov fractional-exponential kernel is considered. Next, we conferred some fascinating and original properties of nominated new fractional derivative with some integral transform operators where all results are significant. The fundamental target of the proposed work is to solve the multidimensional heat equations of arbitrary order by using analytical approach homotopy perturbation transform method and residual power series method, where new fractional operator has been taken in new Yang-Abdel-Aty-Cattani (YAC) sense. The obtained results indicate that solution converges to the original solution in language of generalized Mittag-Leffler function. Three numerical examples are discussed to draw an effective attention to reveal the proficiency and adaptability of the recommended methods on new YAC operator.