On-site infrasound calibration to correct wave parameter estimation.

The International Monitoring System (IMS) has been established as part of the Comprehensive Nuclear-Test-Ban Treaty to monitor nuclear testing and is comprised of infrasound, hydroacoustic, seismic, and radionuclide stations; it is also used more widely by the scientific community for scientific and civilian applications. For the infrasound stations, on-site calibration provides an accurate measure of the sensor (microbarometer + wind-noise reduction system) frequency response, used to monitor that the sensor response remains within tolerance of the baseline established when the station is certified. However, this on-site calibration can also be used when there are issues/defects with the sensors. As a result, the on-site calibration can be used to correct wave parameter estimations and increase the detection capability of the station. Examples using an experimental sensor at the IMS station IS26 (Germany) and IS47 (South Africa) demonstrate that errors of several degrees and tens of m/s can be introduced, under certain conditions, for the back azimuth and trace velocity, respectively. By using the on-site calibration, these errors are removed, and the correct back azimuth, trace velocity and amplitude are retrieved. This can be especially useful for the identification of infrasound signals, and the localization of their sources.

Using dense seismo-acoustic network to provide timely warning of the 2019 paroxysmal Stromboli eruptions.

Stromboli Volcano is well known for its persistent explosive activity. On July 3rd and August 28th 2019, two paroxysmal explosions occurred, generating an eruptive column that quickly rose up to 5 km above sea level. Both events were detected by advanced local monitoring networks operated by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and Laboratorio di Geofisica Sperimentale of the University of Firenze (LGS-UNIFI). Signals were also recorded by the Italian national seismic network at a range of hundreds of kilometres and by infrasonic arrays up to distances of 3700 km. Using state-of-the-art propagation modeling, we identify the various seismic and infrasound phases that are used for precise timing of the eruptions. We highlight the advantage of dense regional seismo-acoustic networks to enhance volcanic signal detection in poorly monitored regions, to provide timely warning of eruptions and reliable source amplitude estimate to Volcanic Ash Advisory Centres (VAAC).

Accurate prediction of the bound conformation of galanthamine in the active site of Torpedo californica acetylcholinesterase using molecular docking.

The alkaloid (-)-galanthamine is known to produce significant improvement of cognitive performances in patients with the Alzheimer's disease. Its mechanism of action involves competitive and reversible inhibition of acetylcholinesterase (AChE). Herein, we correctly predict the orientation and conformation of the galanthamine molecule in the active site of AChE from Torpedo californica (TcAChE) using a combination of rigid docking and flexible geometry optimization with a molecular mechanics force field. The quality of the predicted model is remarkable, as indicated by the value of the RMS deviation of approximately 0.5A when compared with the crystal structure of the TcAChE-galanthamine complex. A molecular model of the complex between TcAChE and a galanthamine derivative, SPH1107, with a long chain substituent on the nitrogen has been generated as well. The side chain of this ligand is predicted to extend along the enzyme active site gorge from the anionic subsite, at the bottom, to the peripheral anionic site, at the top. The docking procedure described in this paper can be applied to produce models of ligand-receptor complexes for AChE and other macromolecular targets of drug design.

Three-dimensional structure of a complex of galanthamine (Nivalin) with acetylcholinesterase from Torpedo californica: implications for the design of new anti-Alzheimer drugs.

The 3D structure of a complex of the anti-Alzheimer drug galanthamine with Torpedo californica acetylcholinesterase is reported. Galanthamine, a tertiary alkaloid extracted from several species of Amarylidacae, is so far the only drug that shows a dual activity, being both an acetylcholinesterase inhibitor and an allosteric potentiator of the nicotinic response induced by acetylcholine and competitive agonists. The X-ray structure, at 2.5A resolution, shows an unexpected orientation of the ligand within the active site, as well as unusual protein-ligand interactions. The inhibitor binds at the base of the active site gorge, interacting with both the acyl-binding pocket and the principal quaternary ammonium-binding site. However, the tertiary amine group of galanthamine does not directly interact with Trp84. A docking study using the program AUTODOCK correctly predicts the orientation of galanthamine in the active site. The docked lowest-energy structure has a root mean square deviation of 0.5A with respect to the corresponding crystal structure of the complex. The observed binding mode explains the affinities of a series of structural analogs of galanthamine and provides a rational basis for structure-based drug design of synthetic derivatives with improved pharmacological properties. Proteins 2001;42:182-191.

The biofiltration of indoor air: implications for air quality.

An alternative method of maintaining indoor air quality may be through the biofiltration of air recirculating within the structure rather than the traditional approach of ventilation. This approach is currently being investigated. Prior to its acceptance for dealing with volatile organic compounds (VOCs) and CO2, efforts were made to determine whether the incorporation of this amount of biomass into the indoor space can have an (negative) impact on indoor air quality. A relatively large ecologically complex biofilter composed of a ca. 10 m2 bioscrubber, 30 m2 of plantings and a 3,500 litre aquarium were established in a 160 m2 'airtight' room in a recently constructed office building in downtown Toronto. This space maintained ca. 0.2 air changes per hour (ACH) compared to the 15 to 20 ACH (with a 30% refresh rate) of other spaces in the same building. Air quality parameters of concern were total VOCs (TVOCs), formaldehyde and aerial spore counts. TVOC and formaldehyde levels in the biofilter room were the same or significantly less than other spaces in the building despite a much slower refresh rate. Aerial spore levels were slightly higher than other indoor spaces but were well within reported values for 'healthy' indoor spaces. Levels appeared to be dependent on horticultural management practices within the space. Most genera of fungal spores present were common indoors and the other genera were associated with living or dead plant material or soil. From these results, the incorporation of a large amount of biomass associated with indoor biofilters does not in itself lower indoor air quality.

The use of biofilters to improve indoor air quality: the removal of toluene, TCE, and formaldehyde.

A biofilter composed of a scrubber, a hydroponic planting system, and an aquatic system with green plants as a base maintained air quality within part of a modern office building. The scrubber was composed of five parallel fiberglass modules with external faces of porous lava rock. The face, largely covered with mosses, was wetted by recirculating water. Air was drawn through the scrubber and the immediately adjacent hydroponic region by a dedicated air handling system. The system was challenged for 4 weeks with three common indoor organic pollutants and removed significant amounts of all compounds. A single pass through the scrubber removed 10% of the trichloroethylene and 50% of the toluene. A single pass lowered formaldehyde air concentrations to 13 micrograms m-3 irrespective of influent levels (ranging between 30 and 90 micrograms m-3). The aquatic system accumulated trichloroethylene but neither toluene nor formaldehyde, suggesting the rapid breakdown of these materials. The botanical components removed some pollutants.

Environment and well-being before and following smoking ban in office buildings.

The purpose of this study was to compare the well-being, salivary cotinine levels and environmental characteristics of office building workers and their workplace before and after the introduction of a smoking ban. The results showed that one year following the ban, there was an ambiguous change in symptom reporting, a trend towards reduced salivary cotinine levels, and an improvement in measured but not in perceived environmental quality.

Respiratory effects and dust exposures in hog confinement farming.

Fifty-three hog confinement farmers and 43 control farmers were studied. Pulmonary function, total and respirable personal dust levels, and responses to a health status questionnaire were obtained for all farmers. The hog farmers' total and respirable personal dust exposures were significantly higher than the respective levels of the control farmers. Higher dust levels were associated with the use of floor (scatter) feeding, indoor feed grinding, and the use of high moisture corn feed. Pork producers reported respiratory symptoms significantly more often than controls. Lung function did not differ between the two groups of farmers, nor could dust exposure levels be related to lung function.

Wood dust and formaldehyde exposures in the cabinet-making industry.

Time-weighted average (TWA) personal total and respirable dust exposures were determined gravimetrically for 48 subjects in 4 cabinet-making plants. TWA personal formaldehyde exposures also were obtained, with the use of 3M 3750 passive monitors. Selective area sampling for formaldehyde was undertaken using two methods. The results obtained with the passive monitors were compared to the standard chromotropic acid impinger method. Considerable variation was noted in the dust exposures. Cabinet-makers exposed to softwoods were found to have a mean exposure of approximately one half of the current applicable ACGIH TWA-TLV, while hard-wood exposure was twice the applicable TWA-TLV. The highest dust exposures were recorded for those workers sanding, the mean total dust being 2.91 mg/m3 (S.E. 0.70) and respirable dust 0.63 mg/m3 (S.E. 0.20). Sanding operations also were found to produce a higher proportion of respirable dust (22%) than other woodworking operations (6%-14%). Workers in assembly areas also were found to have higher dust exposures, likely reflecting the fact that conventional dust collection devices for stationary woodworking equipment are not appropriate for hand held tools and hand sanding. The importance of making respirable dust measurements is discussed. The poor correlation between paired total and respirable dust concentrations indicates that both measurements should be made. Some potential limitations to respirable wood dust sampling using 10 mm nylon cyclones are noted, however. Area dust concentrations were found to be significantly lower than personal exposures, emphasizing the importance of personal sampling data. Formaldehyde vapor exposures were very low, with a mean of 0.06 ppm (S.E. 0.01).

Allergic contact dermatitis due to a biocide containing 5-chloro-2-methyl-4-isothiazolin-3-one.

3 cases of contact allergy due to the biocides 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one are reported. 2 workers exposed to a soluble oil containing these 2 biocides experienced allergic contact dermatitis from them. The 3rd case was that of the chemist who separated the 2 materials for the execution of this investigation. These compounds are chemically related to the biologically active components of Ectimar, Skane M-8 and Proxel CRL. Further instances of contact allergy due to these and related compounds are likely because of the apparently increasing use of such substances as antimicrobial agents in various commercial products.

Respiratory function and exposure-effect relationships in wood dust-exposed and control workers.

The effect of wood dust exposure on 50 cabinet makers was examined. Woodworkers reported more nasal and eye symptoms and more cough, sputum and wheezing than did 49 control workers. More irritated cells were present in the woodworkers' nasal cytological smears. In contrast to the control workers, the woodworkers had a significant decline in lung function over the workshift. An inverse correlation between baseline lung function and an exposure index (mean area dust level multiplied by length of exposure) was demonstrated in the woodworkers. Greater dust exposure was not associated with larger falls in lung function over the work shift.

Tetraethylene glycol diacrylate. A cause of delayed cutaneous irritant reaction and allergic contact dermatitis.

A woman who worked as a materials handler in a plant manufacturing acrylated chemicals developed allergic contact allergy to tetraethylene glycol diacrylate (TTEGDA). Four co-workers experienced skin irritation 12 to 36 hours after skin contact with TTEGDA but had no immediate reaction at the time of exposure. The chemical sensitized the albino guinea pig in the guinea pig maximization test. By varying parameters such as the administration of Freund's complete adjuvent, the intradermal concentration injected for induction, and the diluent used for the injections, it was possible to alter the apparent sensitization potential of TTEGDA.

Allergic contact dermatitis due to urethane acrylate in ultraviolet cured inks.

Seven workers exposed to ultraviolet printing inks developed contact dermatitis. Six cases were allergic and one irritant. A urethane acrylate resin accounted for five cases of sensitisation, one of which was also sensitive to pentaerythritol triacrylate and another also to an epoxy acrylate resin. One instance of allergy to trimethylpropane triacrylate accounted for the sixth case of contact dermatitis in this group of workers. An irritant reaction is presumed to account for the dermatitis in the individual not proved to have cutaneous allergy by patch tests. In this instance trimethylpropane triacrylate was thought to be the most likely irritating agent. Laboratory investigation proved urethane acrylate to be an allergen. The results of investigations of the sensitisation potentials of urethane acrylate, methylmethacrylate, epoxy acrylate resins, toluene-2,4-diisocyanate, and other multifunctional acrylic monomers in the albino guinea pig are presented. The interpretation of such predictive tests is discussed.