Measurement of the ground state 2n pickup probability for 28Si+68Zn and its role in sub-barrier fusion enhancement

The ground state and excited state transfer yields for the 2-neutron pickup channel in the ²⁸Si+⁶⁸Zn system have been measured explicitly. The recoil mass separator at the nuclear Science Centre, New Delhi was used for the measurement. A NaI(T1) detector was used for detecting the deexcitation γ’s from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from the ground state 2 neutron pickup channel with a ground state Q-value of+1.83 MeV.     

Magnetic resonance studies of aniline oligomers formed in the reaction of aniline with 1,1-diphenyl-2-picrylhydrazyl

Aniline oligomers, which are formed in the reaction of aniline with 1,1-diphenyl-2-picrylhydrazyl (DPPH) in methanol and chloroform as solvents, are investigated by means of magnetic resonance techniques. The electron paramagnetic resonance (EPR) spectrum of the products of the reaction of aniline with DPPH (mole ratio, 2∶1) in chloroform solution, and of aniline with DPPH (mole ratio, 1∶2) in methanol solution, were recorded as the reaction progressed, and after the reaction was finished. The spectra of the products after reaction were resolved into the spectra of two species. For the acidified methanol solution the spectrum of one of the species shows hyperfine coupling to two nitrogen atoms with a coupling constanta(2·¹⁴N)=5.8 G, in good agreement with previously reported observations for the radical cation of model aniline trimers. A species is observed in the chloroform solution witha(1·¹⁴N)=11.4 G, which suggests the presence of aniline dimers. Both solutions also show a second signal which is attributed to higher oligomer radical cations with unresolved¹⁴N hyperfine structure.¹H nuclear magnetic resonance (NMR) spectra of aniline and aniline-DPPH solutions in CDCl₃ with the peaks due to DPPHH, the product of reduction of DPPH, were observed. The¹H NMR experiments show that only 15% of the available aniline was consumed, in agreement with the theoretical calculations for the formation of polyaniline-emeraldine base salt under these conditions rather than the sole formation of dimers, which would be expected to consume 33% of the available aniline. This is probably due to formation of partially oxidized long-chain aniline oligomers as the main reaction product.     

Polarographic determination of mixtures of aluminum and gallium

Methods have been described for determining mixtures of aluminum and gallium when the ions are present in approximately the same concentration and when the concentration of aluminum exceeds the concentration of gallium by at least a factor of five. The average error of the determination of aluminum is ±4 to 8% and that of gallium is ± 6 to 8%.     

Calorimetry of dual limitations in yeast cultures

Chemostat cultures of one aerobic fermenting yeast (Saccharomyces cerevisiae) and one aerobic respiring yeast (Kluyveromyces fragilis) have been grown under dual C + N limitation in an isothermal reaction calorimeter. The dual limitations resulted in uncoupled oxidation of part of the glucose, which enabled the culture to adapt the ratio of nitrogen to carbon consumption rates precisely to the N/C ratio that was fed into the calorimeter. This conclusion has been reached based on the calorimetric measurements, which reflect uncoupled respiration conspicuously as abnormal heat yields or ratios of heat release per biomass grown.