Laser oscillation with low quantum defect in Yb:GdVO4, a crystal with high thermal conductivity.

A Yb:GdVO4 single crystal was grown by the Czochralski process. Its thermal conductivity was measured by photothermal analysis and reached 8.1 and 7.1 W m(-1) K(-1) along and perpendicular to the c axis, respectively. These values are in good agreement with the predicted ones. The optical spectroscopy of the crystal, such as its absorption and emission cross sections under the two polarizations, its fluorescence lifetime, and its laser parameters, is investigated. Cw laser oscillation is obtained for what is to our knowledge the first time in this material under titanium sapphire pumping at 984 nm. We obtain 420 mW of output power for a 2% output coupler at 1029 nm. With a thin sample, the laser wavelength decreases to 1015 nm. In this case the quantum defect is as small as 2.9%. The weak heat release of the material suggests good prospects for its use in high-power applications.

Two-frequency Er-Yb:glass microchip laser passively Q switched by a Co:ASL saturable absorber.

Passive Q switching of a two-frequency Er3+-Yb3+:glass laser at 1.55 microm with a new Co2+:La(x)Sr(1 - x)Mg(x - y)Co(y)Al(12 - x)O19 crystal as a saturable absorber is demonstrated. We show that, with an extended cavity setup, the beat frequency between the orthogonally polarized laser eigenstates is continuously tunable by adjustment of the retardance of an intracavity birefringence. A similarly built microchip laser emits two-frequency pulses of 6-ns duration with a beat frequency of as much as 19 GHz. Moreover, two-frequency pulses at 777 nm are obtained by second-harmonic generation in a periodically poled lithium niobate crystal. Such pulses can be useful for applications such as Doppler lidar radar.

Saturable Absorber Cr(4)+:(Sr, Ca)Gd(4)(SiO(4))(3)O Crystals as Q Switches for a Diode-Pumped Nd(3)+:KGd(WO(4))(2) Laser.

Passive Q switching of a diode-pumped Nd(3+):KGd(WO(4))(2) laser is demonstrated by use of Cr(4+):SrGd(4)(SiO(4))(3)O and Cr(4+):CaGd(4)(SiO(4))(3)O crystals as saturable absorbers. An average output power of 40 mW was obtained with a pulse repetition rate of ~0.4 MHz.

Diode-bar end-pumped high-power Nd:Y(3)Al(5)O(12) planar waveguide laser.

A compact high-power planar waveguide laser end pumped by a diode-bar is reported. The waveguide was fabricated by liquid-phase epitaxy and had an 80-microm-thick, 1.5-at. % Nd:Y(3)Al(5)O(12) core on a Y(3)Al(5)O(12) substrate. A maximum output power of 6.2 W was obtained at 1.064 microm when the device was pumped with a 20-W diode bar operating near 807 nm, giving an overall optical-to-optical conversion efficiency of 31%. The total device length was 5 cm.

Directional porosity of porcine small-intestinal submucosa.

Small-intestinal submucosa (SIS) has been shown to be a promising biomaterial for vascular graft applications. This study examines the directionality property of SIS porosity using 35 SIS specimens from 13 pigs. In addition, the effects of the weight of the donor pig, pre-conditioning of 13 additional SIS specimens, and the duration of the test of five additional SIS specimens on such porosity are reported. The porosity from serosal to mucosal direction was found to be four times greater than the porosity in the opposite direction. The weight of the donor pig was not found to be an important factor in SIS porosity. Preconditioning served to increase the average serosal porosity index at 120 mm Hg static water pressure from 2.99 to 8.33 mL/(min cm2). The porosity in the mucosal direction was not affected by preconditioning. Porosity in both directions decreased with increasing test duration. The directionality property of SIS porosity may be an important factor in its success as a vascular graft. The term 'porosity' is used throughout this article, but current standards also refer to the term 'permeability' to describe the passage of liquid through a vascular graft.

Growth and low-threshold laser oscillation of an epitaxially grown Nd:YAG waveguide.

We report 1.064-microm laser operation of an epitaxially grown Nd: YAG planar waveguide with thresholds as low as ~0.7 mW when high-reflectivity mirrors are used. The output is single mode and, when a 83% reflectivity output coupler is used, has a diode pumped slope efficiency of ~40%. Output powers in excess of 60 mW have been obtained when pumping with a Rhodamine 6G dye laser.

Post marketing surveillance of zopiclone: interim analysis on the first 10,000 cases in a clinical study in general practice.

The tolerance of zopiclone, a hypnotic belonging to a new chemical group, the cyclopyrrolones, was studied in a follow-up trial in 23,000 insomniac outpatients treated for 3 weeks. The results from the interim analysis of the first 10,000 cases confirm the efficacy and safety of zopiclone under usual prescribing conditions. The average daily dose of zopiclone was 0.97 +/- 0.21 tablet (7.275 +/- 1.575 mg). The study population included 63.1% of female and 36.9% of male patients; the mean age was 52.3 +/- 16.6 years. 93.1% of the patients completed the trial. 8.2% of the patients experienced adverse reactions which resulted in drug discontinuation in only 2.8% of cases. In the global evaluation, the efficacy was rated excellent or good in more than 80% of the patients.

Chronic liver iron overload in the baboon by ferric nitrilotriacetate. Morphologic and functional changes with special reference to collagen synthesis enzymes.

Two baboons receiving intramuscular injections of ferric nitrilotriacetate over a two-year period were compared with two control baboons. The results indicate that in iron-overloaded animals: liver iron excess was major (maximal liver iron concentration values of 42 mumol/100 mg dry weight for both animals vs 1.3 +/- 0.2 (mean +/- SD) in controls) and chronic (for 15 months liver iron concentrations were higher than 15); iron deposition, although less abundant than in sinusoidal cells, was pronounced within parenchymal cells; serum transaminase activities were markedly increased; rare foci of perisinusoidal fibrosis were observed in areas of massive iron overload; and a dramatic decrease in hepatic 4-prolyl-hydroxylase activity was found, in contrast with unchanged glucosyltransferase and galactosyltransferase activities. In conclusion these findings suggest that, in our model, chronic liver iron overload: exerts a marked biochemical cytolytic effect; and does not produce significant hepatic fibrosis, possibly related to an inhibiting effect of ferric nitrilotriacetate complex on 4-prolyl-hydroxylase activity.

Experimental hepatic iron overload in the baboon: results of a two-year study. Evolution of biological and morphologic hepatic parameters of iron overload.

Four baboons receiving intramuscular iron for 15 months were compared with two control baboons. From the overall two-year observation period the following data emerge: (1) The baboon is a suitable animal for obtaining a massive and chronic iron overload. Liver iron concentrations reached very high levels (ranging from 41.3 to 180.6 mumol/100 mg dry weight vs 1.7 +/- 0.5, mean +/- SEM, in controls), and a major liver iron overload (ie, with concentration values greater than or equal to 18) was present in all four animals for an average period of 16.5 months (range 14-19). (2) When compared with human hepatic iron-overload disorders, iron distribution was similar to that observed in secondary (transfusional) hepatic siderosis since iron deposits were found primarily in sinusoidal cells. However, a marked parenchymal siderosis was also obtained close to that observed in primary (genetic) siderosis. Iron toxicity was present biologically as indicated by an increase in serum transaminases. Histologically, a slight fibrosis was observed in the most heavily iron-overloaded baboon. On the whole, this study of subhuman primates brings new evidence that iron per se has only a minor hepatic damaging effect. It also suggests that the iron-overloaded baboon liver provides a promising tool for the study of liver cell disturbances in human iron overload.