Airborne bacteria structure and chemical composition relationships in winter and spring PM10 samples over southeastern Italy.

The Redundancy Discrimination Analysis (RDA) and Spearman correlation coefficients were used to investigate relationships between airborne bacteria at the phylum and genus level and chemical species in winter and spring PM10 samples over Southeastern Italy. The identification of main chemical species/pollution sources that were related to and likely affected the bacterial community structure was the main goal of this work. The 16S rRNA gene metabarcoding approach was used to characterize airborne bacteria. Seventeen phyla and seventy-nine genera contributing each by mean within-sample relative abundance percentage > 0.01% were identified in PM10 samples, which were chemically characterized for 33 species, including ions, metals, OC, and EC (organic and elemental carbon, respectively). Chemical species were associated with six different pollution sources. A shift from winter to spring in both bacterial community structure and chemical species mass concentrations/sources and the relationships between them was observed. RDA triplots pointed out significant correlations for all tested bacterial phyla (genera) with other phyla (genera) and/or with chemical species, in contrast to correlation coefficient results, which showed that few phyla (genera) were significantly correlated with chemical species. More specifically, in winter Bacillus and Chryseobacterium were the only genera significantly correlated with chemical species likely associated with particles from soil-dust and anthropogenic pollution source, respectively. In spring, Enterobacter and Sphingomonas were the only genera significantly correlated with chemical species likely associated with particles from the anthropogenic pollution and the marine and soil-dust sources, respectively. The results of this study also showed that the correlation coefficients were the best tool to obtain unequivocal identifications of the correlations of phyla (genera) with chemical species. The seasonal changes of the PM10 chemical composition, the microbial community structure, and their relationships suggested that the seasonal changes of atmospheric particles may have likely contributed to seasonal changes of bacterial community in the atmosphere.

Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements.

Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ1, λ2, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 µm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 µm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 µm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but the LR and AOT dependence on wavelength was stronger for CP than for DP aerosols. The plots of the lidar ratio values at 355 nm versus the mean columnar values of the 532-1064 nm Ångström coefficient (Å c), the fine mode radius, the fine mode fraction at 532 nm (η c), and the color ratio, respectively, furthermore revealed the greater ability of the Å c and η c values to characterize different aerosol types.

Columnar and ground-level aerosol optical properties: sensitivity to the transboundary pollution, daily and weekly patterns, and relationships.

Columnar and ground-level aerosol optical properties co-located in space and time and retrieved from sun/sky photometer and nephelometer measurements, respectively, have been analyzed to investigate the impact of local and transboundary pollution, to analyze their relationships, and hence to contribute to the aerosol load characterization over the Central Mediterranean. The aerosol optical depth (AOD) at 440 nm, the Ångström exponent (Å) calculated from the AOD at 440 and 675 nm, and the asymmetry parameter (g col ) at 440 nm represent the investigated columnar aerosol parameters. The scattering coefficient (σ p) at 450 nm, the scattering Ångström exponent (å) calculated from σ p at 450 and 635 nm, and the asymmetry parameter (g) at 450 nm are the corresponding ground-level parameters. It is shown that the columnar and ground-level aerosol properties were significantly and similarly affected by the main airflows identified with backtrajectory cluster analysis. The yearly averaged daily evolution of σ p, å, and g was fairly correlated to the one of the AOD, Å, and g col , respectively. These results indicate that the aerosol particles were on average characterized by similar yearly averaged optical properties up to the ground level. In particular, the yearly means of columnar and ground-level Ångström exponents, 1.3 ± 0.4 and 1.1 ± 0.4, respectively, which are close to one, reveal a coarse-mode aerosol contribution in addition to the fine-mode particle contribution up to the ground level. Hourly means, day-by-day, and seasonal daily patterns of ground-level parameters were, however, very weakly correlated with the corresponding columnar parameters. The large impact of the local meteorology on the daily evolution of the ground-level aerosol properties, which makes the impact of long-range transported particles less apparent, was mainly responsible for these last results. It has also been found that columnar Ångström exponents much smaller than one may not be linked to å values smaller than 1. This may occurs when coarse-mode particle plumes, advected at high altitudes, do not penetrate inside the planetary boundary layer. Ångström exponents smaller than 1 are due to a significant contribution of coarse-mode particles as dust particles. Therefore, it is shown that å represents one of the best parameters to infer the contribution of coarse-mode particles at the ground level. The daily evolution of the aerosol properties referring to working days (Monday to Friday) and Sunday and the weekly cycle have suggested that the aerosol source contributions varied during the weekends. In particular, the AOD was characterized by a negative weekly cycle (higher AOD values during the weekend than during the weekdays), the Sunday σ p daily mean was 11 % larger than the Monday value, and å reached the highest value on Sunday. The impact up to the ground level of the weekdays' transboundary pollution, which reaches the monitoring site during the weekends, has likely contributed to these results.

Monitoring O3 with solar-blind Raman lidars.

The benefits of retrieving ozone concentration profiles by a use of a single Raman signal rather than the Raman differential absorption lidar (DIAL) technique are investigated by numerical simulations applied either to KrF- (248 nm) or to quadrupled Nd:YAG- (266 nm) based Raman lidars, which are used for both daytime and nighttime monitoring of the tropospheric water-vapor mixing ratio. It is demonstrated that ozone concentration profiles of adequate accuracy and spatial and temporal resolution can be retrieved under low aerosol loading by a single Raman lidar because of the large value of the ozone absorption cross section both at 248 nm and at 266 nm. Then experimental measurements of Raman signals provided by the KrF-based lidar operating at the University of Lecce (40 degrees 20'N, 18 degrees 6'E) are used to retrieve ozone concentration profiles by use of the Raman DIAL technique and the nitrogen Raman signal.

Tolerability of meloxicam in patients with histories of adverse reactions to nonsteroidal anti-inflammatory drugs.

BACKGROUND: Adverse reactions to nonsteroidal anti-inflammatory drugs (NSAIDs) are frequent, particularly among patients with chronic urticaria or asthma. The need to identify an alternative drug that is safe and reliable is a common problem in clinical practice. OBJECTIVE: To assess the tolerability of meloxicam, a new NSAID that selectively inhibits the inducible isoform of cyclooxygenase, in a group of NSAID-sensitive patients. PATIENTS AND METHODS: We studied 177 patients who had suffered adverse reactions to one or more NSAIDs. Cutaneous reactions were reported by 83.1% of the subjects (urticaria in 55, angioedema in 52, urticaria/angioedema in 39, and maculopapular rash in 1), respiratory symptoms by 3.9%, both cutaneous and respiratory symptoms by 9%, Stevens-Johnson's syndrome by 2.3%, and anaphylactoid reactions by 1.7%. All subjects underwent a single-blind, placebo-controlled oral challenge with divided therapeutic doses of meloxicam (1.9 mg + 5.6 mg 1 hour later = cumulative dose 7.5 mg). RESULTS: Positive reactions were observed in only two cases (1.1%), both manifested exclusively by cutaneous symptoms (urticaria/angioedema in one case and maculopapular rash/facial edema in the second). CONCLUSION: Meloxicam seems to be well tolerated by NSAID-sensitive subjects whose reactions are manifested by urticaria/angioedema. Additional study is needed for a more complete assessment of its tolerability in patients with aspirin-induced asthma and other severe manifestations of NSAID sensitivity.

Water-vapor mixing-ratio measurements in the solar-blind region.

It is shown that, under clear sky conditions, water-vapor mixing-ratio measurements by solar-blind Raman lidars can be improved if the differential transmissivity is calculated by use of a single Raman signal instead of the usual Raman differential absorption lidar method, which allows one to exploit the large absorption cross section of ozone in this spectral region. We present a discussion of statistical and systematic errors in both methods and show the results of a numerical simulation.

Deposition of SiO2 films with high laser damage thresholds by ion-assisted electron-beam evaporation.

SiO(2) thin films (approximately 100 nm thick) with transmittivity and a laser damage threshold nearly equal to those of bulk material are deposited on silica substrates by the technique of ion-assisted electron-beam evaporation. The influence of film packing density on the laser damage threshold is investigated by the technique of photoacoustic probe beam deflection. It is shown that films with lower packing density may have a higher laser damage threshold and as a consequence better heat dissipation.

Phase shift of stepwise reflectivity profile mirrors.

The effects of phase shifts in laser beams transmitted by output couplers with a stepwise reflectivity profile have been experimentally investigated with a XeCl laser. It is shown that the phase distortions of the cavity output coupler affect significantly the propagation properties of the output laser beam but do not affect the output beam energy and pulse width.

Output coupler design of unstable cavities for excimer lasers.

We tested the performance of a XeCl laser with unstable resonators using as an output coupler a phase unifying (PU) mirror, a super-Gaussian mirror, and a hard-edge mirror. The quantitative impact of the output coupler design on the energy extraction efficiency, near-field profile, far-field energy distribution, and spatial coherence time evolution has been investigated. Laser beams of larger brightness have been obtained with the PU unstable cavity. A faster growth of the laser beam spatial coherence has been observed with the PU cavity by time-resolved, far-field measurements.

Beam-divergence control of excimers with plane-parallel Gaussian cavities.

Plane-parallel cavities with Gaussian-reflectivity-profile mirrors as full reflectors were applied to a XeCl laser, and the near- and the far-field characteristics of the laser radiation were analyzed. It is shown that excimer lasers fitted with plane-parallel Gaussian cavities deliver laser radiation with a beam-quality factor M(2) that is more than 50% smaller than that of laser beams delivered by conventional plane-parallel cavities. The effect of the Gaussian mirror spot size on M(2) was also investigated, and it is shown that the narrowing of the Gaussian mirror spot size reduces the beam-quality-factor value.

Numerical modeling of short-pulse excimer lasers with negative branch unstable cavities.

A one-dimensional code for the numerical simulation of negative branch unstable resonators with an intracavity aperture that are applied to high-gain, short-pulse XeCl lasers is described. The model predicts near- and far-field performance of the output laser beams. The intracavity aperture size is shown as an important parameter for control of the output beam energy and divergence. A comparison with experimental measurements is presented.

Phase-conjugated XeCl laser resonator.

Self-Q switching of a XeCl laser fitted with a resonator containing a stimulated-Brillouin-scattering phase-conjugate reflector is demonstrated. Q-switched laser pulses of 0.2-mJ energy and 2.5-ns duration and with a divergence close to the diffraction limit were obtained. A spectral narrowing of the two strong lines at 307.98 and at 308.19 nm exhibited by the XeCl laser spectrum was also observed.

Super-Gaussian resonators for long-pulse XeCl lasers.

Near-diffraction-limited laser beams of high energy have been achieved with a long-pulse (110-ns) XeCl laser fitted with a super-Gaussian unstable cavity of magnification M = 2.7. It has been found that when the super-Gaussian output coupler is replaced with a hard-edge aluminized mirror of radius equal to the super-Gaussian mirror spot size, the output laser energy is reduced by 10%, whereas the beam divergence increases more than 50%.

Experimental characterization of a self-filtering unstable resonator applied to a short pulse XeCl laser.

A self-filtering unstable resonator with magnification |M| = 5 has been applied to a pulsed UV-preionized XeCl excimer laser. In agreement with numerical results it is experimentally shown that less than two cavity round trips are needed to establish a steady state lowest-order mode. A diffraction-limited laser beam with a brightness of 1.5 x 10(13) W cm(-2) sr(-1) has been obtained.

Stimulated Raman scattering in H(2)-Ar mixtures.

Stimulated Raman scattering experiments have been performed in H(2) and in H(2)-Ar mixtures with a UV-preionized XeCl discharge laser (308 nm) as the pump. The energy conversion efficiency from the pump laser beam to Stokes beams has been investigated as a function of Ar concentration and pumping energy. It has been found that, in the H(2)-Ar mixture with a 50% Ar concentration, the energy conversion efficiency to the first Stokes beam was more than 80% higher than that obtained in H(2) at the same total pressure and pump energy (60 mJ).

Gain measurements in the KrCl excimer laser.

The single-pass/double-pass amplified spontaneous emission technique has been used to measure the net gain at 222.4 nm in a discharge-pumped UV-preionized KrCl laser. The net gain has been measured as a function of pump rate and total pressure in He- and Ne-based gas mixtures. A maximum net gain of 0.15 cm(-1) has been obtained in a 0.09% HC1/10.1% Kr/1.5% He/88.3% Ne mixture at a total pressure of 355 kPa and at a specific power loading of approximately 21 MW/cc. The data presented are compared with previous net gain measurements performed using the passive absorption cell method.