ABSTRACT
A 2 µm Ho-doped ytrrium lithium fluoride (Ho:YLF) laser end-pumped by a 1.94 µm Tm:fiber laser was developed. A laser system of a ring resonator oscillator and amplifier was operated at repetition rates of 200-5000 Hz at room temperature. The Q-switched outputs were 7.4 W at 5000 Hz and 4.25 W at 200 Hz. Injection seeding was applied to the ring resonator, and single-mode laser emission was obtained. The Tm:fiber-laser-pumped Ho:YLF laser was first used for Doppler wind lidar measurements, and wind profiles were obtained up to ranges of about 15 km in a range resolution of 96 m and an integration time of 1 s.
ABSTRACT
We disseminated an ultra-broadband optical frequency reference based on a femtosecond (fs)-laser optical comb through a kilometer-scale fiber link. Its spectrum ranged from 1160 nm to 2180 nm without additional fs-laser combs at the end of the link. By employing a fiber-induced phase noise cancellation technique, the linewidth and fractional frequency instability attained for all disseminated comb modes were of order 1 Hz and 10-18 in a 5000 s averaging time. The ultra-broad optical frequency reference, for which absolute frequency is traceable to Japan Standard Time, was applied in the frequency stabilization of an injection-seeded Q-switched 2051 nm pulse laser for a coherent light detection and ranging LIDAR system.
ABSTRACT
Q-switched operation of a diode-side-pumped, conduction-cooled Tm,Ho:YLF laser oscillator with 100-mJ output at a pulse repetition rate of 20 Hz and an eye-safe wavelength of 2-µm was achieved. The noncomposite Tm,Ho:YLF laser rod was conduction-cooled down to -80°C through thermal contact of In films from Cu heat sinks, and the laser diode arrays were conduction-cooled to approximately 20°C using Cu heat sinks in a vacuum container. A ring resonator of 3.86 m length with an acousto-optic Q-switch was used. The pulse width was 125 ns, and optical-to-optical efficiency was approximately 7% for an output of 100 mJ. The laser is used at 2.05 µm for applications of Doppler wind lidar measurements, CO2 differential absorption lidar measurements, and aerosol profiling.
ABSTRACT
The generation of stable dual-wavelength pulses from an actively Q-switched Nd:YAG laser operating at 1064 and 1319 nm was demonstrated. Pulse energies of the dual-wavelength laser were extracted by two temporally separated stimulated-emission processes for a single pumping process, thereby avoiding line competition between the two laser transitions. Total energy of the order of 20 mJ was achieved for the two pulses, and the ratio of the pulse energies of the two lasers could be selected by adjusting the output couplings. The pulse-to-pulse fluctuations for the lasers operating at 1319 and 1064 nm were 4.7%-4.8% and 1.5%-2.6%, respectively, which were almost equivalent to those for a single emission line in our system. The experimentally observed laser performance agreed reasonably well with theoretical predictions.
ABSTRACT
We have developed a conductively cooled, Q-switched 2 µm laser with a triangular-prism Tm,Ho:LLF rod. Using a fused-silica acousto-optic Q-switch, the laser produced an output energy of 30 mJ in a single Q-switched pulse at a pulse repetition frequency of 5 Hz. Although the laser rod had polished lateral surfaces, no parasitic oscillation occurred, even at the maximum pumping level. In addition, broadly tunable laser performance was achieved with a birefringent filter plate under relatively large output coupling. The laser could be continuously tuned from 2051 to 2069 nm. Measured tuning characteristics were in reasonable agreement with calculated results.
ABSTRACT
Zearalenone (ZON) is a mycotoxin with estrogenic activity, produced by members of Fusarium species, and is found worldwide in a number of cereal crops. It is known to have four active metabolites (α-zearalenol (α-ZOL), ß-zearalenol (ß-ZOL), α-zearalanol (α-ZAL), and ß-zearalanol (ß-ZAL)). A highly sensitive analytical method using liquid chromatography/tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) has been established and validated in order to analyze ZON and its metabolites in beer and malt samples. The metabolism of ZON in the course of beer fermentation was further characterized using the artificially contaminated wort by this established method. In the fermented sample, 85.9% of ZON was converted to ß-ZOL, which has lower estrogenic activity than that of ZON. These findings indicate that the health risk to humans due to ZON in beer is reduced during the fermentation process.
Subject(s)
Beer/analysis , Estrogens, Non-Steroidal/metabolism , Food Contamination/analysis , Saccharomyces/metabolism , Zearalenone/metabolism , Estrogens, Non-Steroidal/analysis , Fermentation , Zearalenone/analysisABSTRACT
A coherent 2 microm differential absorption and wind lidar (Co2DiaWiL) was developed to measure CO(2) concentration and line-of-sight wind speed. We conductively cooled a pumping laser head to -80 degrees C and diode arrays to approximately 20 degrees C. A Q-switched laser outputs an energy of 80 mJ (pulse width 150 ns (FWHM), pulse repetition frequency up to 30 Hz). CO(2) measurements made over a column range (487-1986 m) for 5 min accumulation time pairs achieved 0.7% precision. Line-of-sight wind speeds for ranges up to approximately 20 km and returns from a mountainside located 24 km away from the Co2DiaWiL were obtained.
ABSTRACT
Penicillium islandicum produces luteoskyrin (LUT), a yellow rice toxin that has been found frequently in rice. However, conventional analytical methods for determining LUT are limited, are complicated, and exhibit low sensitivity. In this study, an analytical method more sensitive and simple based on high-performance liquid chromatography combined with electrospray ionization mass spectrometry was developed. The cleanup procedure of the method was one step, using a solid-phase extraction cartridge. An isocratic mobile-phase system, consisting of acetonitrile-water-acetic acid (50:49:1 [vol/vol/vol]) at a flow rate of 0.2 ml/min, was utilized to obtain the best resolution. Our method showed good linearity (r = 0.9993, 0.5 to 50 ng/g) and high repeatability (relative standard deviation = 8.9 and 5.1% at levels of 0.5 and 10 ng/g, respectively) in the fortification test. The detection and quantification limits for the method in multiple-reaction monitoring mode were 0.1 and 0.3 ng/g, respectively. The average recovery of LUT in spiked rice at 0.5 and 10 ng/g was 80.7 and 85.2%, respectively. The method developed in this study should be applicable to survey LUT in rice, with high sensitivity, selectivity, and rapidity.
Subject(s)
Chromatography, High Pressure Liquid/methods , Food Contamination/analysis , Naphthoquinones/analysis , Oryza/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Reproducibility of Results , Sensitivity and Specificity , Solid Phase ExtractionABSTRACT
A new chlorinated cyclic pentapeptide, hydroxycyclochlorotine (1), has been isolated from Penicillium islandicum, and the structure including absolute stereochemistry of 1 and conformational properties of 1 and cyclochlorotine (2) in DMSO-d6 were elucidated by using extensive 2D NMR and chemical means. Hydroxycyclochlorotine (1) and astin B (3) from Aster tataricus, each containing an allo threonine at residue 2, have a cis proline configuration, whereas cyclochlorotine (2) has two conformational states in solution, which may be produced from cis-trans isomerization of the proline amide bond. The presence of an intramolecular hydrogen bond between Ser (3)-NH and a hydroxyl oxygen atom of alloThr (2) may serve to maintain the backbone conformation with a cis proline amide bond.
Subject(s)
Penicillium/chemistry , Peptides, Cyclic/chemistry , Peptides, Cyclic/isolation & purification , Molecular StructureABSTRACT
An uncooled microbolometer-array thermal infrared camera has been incorporated into a remote sensing system for radiometric sky imaging. The radiometric calibration is validated and improved through direct comparison with spectrally integrated data from the Atmospheric Emitted Radiance Interferometer (AERI). With the improved calibration, the Infrared Cloud Imager (ICI) system routinely obtains sky images with radiometric uncertainty less than 0.5 W/(m(2 )sr) for extended deployments in challenging field environments. We demonstrate the infrared cloud imaging technique with still and time-lapse imagery of clear and cloudy skies, including stratus, cirrus, and wave clouds.
ABSTRACT
A diode-pumped Tm, Ho:GdVO4 laser with a side-pumping configuration is demonstrated for the first time to our knowledge. Optimum Tm and Ho dopant concentrations for GdVO4 are somewhat lower than those for garnet and fluoride crystals. With a 3% Tm, 0.3% Ho:GdVO4 crystal an output energy of 31.2 mJ and a slope efficiency of 14.5% were obtained in normal-mode operation at room temperature.
