Bistable polarization switching in mutually coupled vertical-cavity surface-emitting lasers

We theoretically investigate the polarization-resolved dynamics of two vertical-cavity surface-emitting semiconductor lasers that are mutually coupled through coherent optical injection. We find a sequence of bistable polarization switchings that can be induced by changing either the coupling strength or the optical propagation phase. The successive polarization switchings are correlated with the creation of new compoundcavity modes when these parameters are continuously varied.     

Effect of selenium on the Hg,Zn, Fe and Co content of yeast cells

The yeast cells, Saccharomyces cerevisiae, were exposed to Hg²⁺ ions (10^–4M) and SeO₂ (2·10^–4–10^–2M) or Se- methionine (2·10^–4M). Instrumental neutron activation analysis (INAA) was used to analyze changes in the Hg, Zn, Fe and Co levels in these cells. When the yeast was incubated in a medium containing 10^–3M and 10^–2M SeO₂, the Hg content of the yeast markedly increased. It was also found that the uptake of Se and Hg influenced the levels of Zn, Fe and Co found in the cells. While the presence of Se-methionine (Se-Met), SeO₂ or Hg²⁺ ions caused increases in the intracellular Zn levels, the combined presence of Hg²⁺ and SeO₂ and their assumed interaction, reduced the efficiency of Se for increasing the Zn content of yeast.     

Semileptonic decays of charmedD ± meson

Using the ACCMOR spectrometer equipped with a vertex telescope of high resolution silicon microstrip detectors 74 decays \(D^ + \to \bar K^{*0} (892)e^ + v_e \) (andcc.) withx _F <0.4 have been observed in 200 GeV π^? Be interactions. The cross-section forD ^± production, itsx _F -dependence in the central region and theD ^± lifetime have been measured.     

Hadronic ϕ production and the lund model for lowp T interactions

Experimental results on inclusive ? production are compared with the Lund model for lowp _T hadronic interactions. The data is based on a sample of 600,000 ? mesons in the kinematic rangep _T <1.0 (GeV/c)² and 0.0<x _F<0.4, produced in π^±,K ^±,p and \(\bar p\) Be interactions at 100 GeV/c and 120 GeV/c incident momentum. The Lund model reproduces the shapes of the longitudinal differential cross sections reasonably well, but the relative cross sections for incident, π,K andp show a discrepancy with the data.     

Mass transfer enhancement in supercritical fluids extraction by means of power ultrasound

The use of high-intensity ultrasound represents an efficient manner of producing small scale agitation, enhancing mass transfer on supercritical fluids (SF) extraction processes. In this way, a supercritical CO(2) extraction of oil from particulate almonds using power ultrasound was studied. To examine the effect of the acoustic waves all experiments were performed with and without ultrasound. A power ultrasonic transducer for a working frequency of about 20 kHz was constructed and installed inside a high-pressure 5 l SF extractor. The experimental tests were carried out with CO(2) at 280 bar and 55 degrees C. Grounded almonds with an oil content of about 55%, in an amount of 1500 g were deposited inside the SF reactor where the solvent was introduced at a flow rate of 20 kg/h. The results show that the kinetics and the extraction yield of the oil were enhanced by 30% and 20% respectively, when a power of about 50 W was applied to the transducer. The average time of each extraction process was of about 8 h and 30 min. In addition, the transducer was also used as a sensitive probe capable to detect the phase behavior of supercritical fluids when it was driven with low power signals.