Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.

ON THE RATE-EQUATIONS OF SEMICONDUCTOR-LASERS FOR MEASURING SPONTANEOUS EMISSION FACTOR

The rate equations used for measuring spontaneous emission factor beta is examined through the comparison of numerical results, The results show that beta obtained by using total spontaneous emission rate R(sp) = N/tau sp is about double of that using R(sp) = BN2, The magnitude difference between the measured beta and that predicted by classical theory [8] will disappear by using more reasonable R(sp) = BN2. The results also show that the magnitude of beta may be underestimated by ignoring the nonradiative recombination rates.

Dependence of wet etch rate on deposition, annealing conditions and etchants for PECVD silicon nitride film

The influence of deposition, annealing conditions, and etchants on the wet etch rate of plasma enhanced chemical vapor deposition (PECVD) silicon nitride thin film is studied. The deposition source gas flow rate and annealing temperature were varied to decrease the etch rate of SiN_x:H by HF solution. A low etch rate was achieved by increasing the SiH_4 gas flow rate or annealing temperature, or decreasing the NH_3 and N_2 gas flow rate. Concen-trated, buffered, and dilute hydrofluoric acid were utilized as etchants for SiO_2 and SiN_x:H. A high etching selectivity of SiO_2 over SiN_x:H was obtained using highly concentrated buffered HF.

1 GHz Repetition Rate CW Mode-locked Nd∶YVO_4 Laser

A diode-pumped CW mode-locked Nd

Low-timing-jitter, stretched-pulse passively mode-locked fiber laser with tunable repetition rate and high operation stability

We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 mu m wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice.