ABSTRACT
We propose and demonstrate a 1.50-mum- band gain-shifted thulium-doped fiber amplifier (TDFA) by using a novel dual-wavelength (1.05and1.56 -mum) pumping scheme for what we believe is the first time. By providing a small amount of 1.56-mum power to a conventional upconversion-pumped TDFA, we successfully demonstrated a small-signal gain larger than 25 dB and a noise figure of 5 dB in a 1475-1510-nm band.
ABSTRACT
We have investigated the temperature dependence of output performances for 970-nm diode-pumped Yb:YAG (Yb(3+):Y(3)Al(5)O(12)) and Yb:LuAG (Yb(3+):Lu(3)Al(5)O(12)) lasers over the wide temperature range from 80 to 310 K. Temperature-optimized operation was experimentally demonstrated at around 160 K and was theoretically confirmed by taking into account the absorption spectra change of Yb crystals at low temperatures. Cooling the crystal to below 160 K caused a narrowing of the absorption bandwidth and led to a decrease in output power and efficiency.
ABSTRACT
We have demonstrated dual-wavelength continuous-wave oscillation at 3 and 2 mum with a Ho-doped ZrF(4)- BaF(2)- LaF(3)- AlF(3)- NaF fluoride-glass fiber laser by use of a cascade oscillation scheme. We have shown that the fiber laser operates with a high slope efficiency of 52% (at 3 and 2microm) with respect to the absorbed pump power. With a 6.5-m-long fiber we achieved an output power of 90 mW at each of the wavelengths that was limited only by the pump power, and the 3-microm output power is to our knowledge higher than any previously reported level with 3-mum Ho(3+) -doped fiber lasers.
ABSTRACT
We describe a simple design, laser-diode-pumped cw Nd:YAG active-mirror laser and present a thermal analysis of the crystal. A cw output power of 2.4 W and an M(2) beam quality value of less than 1.9 at an incident pumping power of 8.9 W were obtained. From the thermal analysis we predict that the output power can be increased by increasing the pump beam diameter and the pump power at a constant excitation density.
ABSTRACT
To study the correlation between emetic toxin and HEp-2 vacuole activity produced by Bacillus cereus isolated from an outbreak of vomiting-type food poisoning, some properties and emetic activities of both purified HEp-2 factor (cereulide) and partially purified factor to rhesus monkeys were determined. The results indicate that both cereulide and partially purified factor were very stable to digestion with proteolytic enzymes, different pH, and heating. Vomiting was induced in the rhesus monkeys orally administered with both substances. From these findings, cereulide (or HEp-2 vacuole factor) is strongly suggested to be an emetic toxin itself.
Subject(s)
Bacillus cereus/chemistry , Bacterial Toxins/toxicity , Depsipeptides , Emetics/toxicity , Enterotoxins/toxicity , Peptides, Cyclic/toxicity , Administration, Oral , Animals , Bacterial Toxins/administration & dosage , Bacterial Toxins/isolation & purification , Capillary Permeability , Cell Line , Emetics/administration & dosage , Emetics/isolation & purification , Enterotoxins/administration & dosage , Enterotoxins/isolation & purification , Hemolysis , Hot Temperature , Hydrogen-Ion Concentration , Macaca mulatta , Mice , Pepsin A , Peptides, Cyclic/administration & dosage , Peptides, Cyclic/isolation & purification , Trypsin , Vacuoles/drug effectsSubject(s)
Calcium/pharmacokinetics , Phosphorus/pharmacokinetics , Terbium/toxicity , Absorption/drug effects , Administration, Oral , Animals , Bone and Bones/metabolism , Brain/metabolism , Calcium/blood , Feces/chemistry , Intestinal Absorption/drug effects , Kidney/metabolism , Liver/metabolism , Lung/metabolism , Male , Myocardium/metabolism , Pancreas/metabolism , Phosphorus/blood , Rats , Rats, Wistar , Regression Analysis , Spleen/metabolism , Terbium/administration & dosage , Thymus Gland/metabolism , Tissue Distribution/drug effectsABSTRACT
Toxicokinetic parameters of gamma-chlordane (GCD) after oral administration of various doses of radio-labelled GCD (50 micrograms/kg-10 mg/kg) were compared. Absorption of GCD were about 80% in both 0.1 and 1.0 mg/kg groups. Distributions of GCD (50 micrograms/kg and 10 mg/kg) into the liver and kidney were rapid and those into adipose tissues were relatively slow. Concentrations of GCD in adipose tissues became highest at 16 hr after administration and became about 10 times more than those in the liver. The initial concentrations of GCD calculated by two-compartment open model in high dose group (10 mg/kg) were about 200-300 times higher than those in low dose group (50 micrograms/kg). Half lives of GCD in low dose group had a tendency to be a little longer than those in high dose group. This difference seemed to be caused by the accumulation of oxychlordane in low dose group.
