Air

The allergist is generally recognized as possessing the greatest expertise in relating airborne contaminants to respiratory health, both atopic and nonatopic. Consequently, allergists are most often asked for their professional opinions regarding the appropriate use of air-cleaning equipment. This rostrum serves as a resource for the allergist and other health care professionals seeking a better understanding of air filtration.

This paper presents the results of ground vibration measurements carried out in Hisarcik Boron open pit mine located on the west side of central Anatolia near Kütahya province in Turkey. Within the scope of this study to predict peak particle velocity (PPV) level for this site, ground vibration components were measured for 304 shots during bench blasting. In blasting operations, ANFO (blasting agent), gelatin dynamite (priming), and delay electric detonators (firing) were used as explosives. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events using two different types of vibration monitors (one White Mini-Seis and one Instantel Minimate Plus Model). The absolute distances between shot points and monitor stations were determined using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of PPV. Then, the data pairs of scaled distance and particle velocity obtained from the 565 event records were analyzed statistically. At the end of statistical evaluation of the data pairs, an empirical relation which gives 50% prediction line with a reasonable correlation coefficient was established between PPV and scaled distance.

When Campylobacter jejuni NCTC 11351 was grown microaerobically in rich medium at 39°C, entry into stationary phase was followed by a rapid decline in viable numbers to leave a residual population of 1% of the maximum number or less. Loss of viability was preceded by sublethal injury, which was seen as a loss of the ability to grow on media containing 0.1% sodium deoxycholate or 1% sodium chloride. Resistance of cells to mild heat stress (50°C) or aeration was greatest in exponential phase and declined during early stationary phase. These results show that C. jejuni does not mount the normal phenotypic stationary-phase response which results in enhanced stress resistance. This conclusion is consistent with the absence of rpoS homologues in the recently reported genome sequence of this species and their probable absence from strain NCTC 11351. During prolonged incubation of C. jejuni NCTC 11351 in stationary phase, an unusual pattern of decreasing and increasing heat resistance was observed that coincided with fluctuations in the viable count. During stationary phase of Campylobacter coli UA585, nonmotile variants and those with impaired ability to form coccoid cells were isolated at high frequency. Taken together, these observations suggest that stationary-phase cultures of campylobacters are dynamic populations and that this may be a strategy to promote survival in at least some strains. Investigation of two spontaneously arising variants (NM3 and SC4) of C. coli UA585 showed that a reduced ability to form coccoid cells did not affect survival under nongrowth conditions.

Sum frequency generation (SFG) vibrational spectroscopy has been applied to investigate surface structures of an amphiphilic surface-active block copolymer (SABC) film deposited on a CaF 2 substrate, in air and in water in situ. Developed as a surface-active component of an antifouling coating for marine applications, this amphiphilic triblock copolymer contains both hydrophobic fluorinated alkyl groups as well as hydrophilic ethoxy groups. It was found that surface structures of the copolymer film in air and in water cannot be probed directly using the SFG experimental geometry we adopted because SFG signals can be contributed from the polymer/air (or polymer/water) interface as well as the buried polymer/CaF 2 substrate interface. Using polymer films with varied thicknesses, structural information about the polymer surfaces in air and in water can be deduced from the detected SFG signals. With SFG, surface restructuring of this polymer has been observed in water, especially the methyl and methylene groups change orientations upon contact with water. However, the hydrophobic fluoroalkyl group was present on the surface in both air and water, and we believe that it was held near the surface in water by its neighboring ethoxy groups.

The thermal oxidation of 2-chlorophenol (2-CP) in air was investigated using a perfectly stirred reactor at 1 atm over the temperature range 450–900 °C. The relative concentration of 2-CP was 1000 ppmV (equivalence ratio Φ = 0.03). About fifty organic products were identified as trace species. The concentration profiles of 2-CP, carbon oxides as well as those of seventeen major organic intermediates and six non-to-lower chlorinated dioxins and furans were presented as a function of temperature for a residence time of 2 s. The most abundant intermediate products were carbon monoxide, 2 H-pyran-2-one, chlorobenzene, 4-cyclopenten-1,3-dione, phenol, benzofuran, 2-chlorohydroquinone and 2-indanone. These concentration profiles have revealed that temperatures of at least 900 °C were needed to completely oxidize 2-CP, CO and all other organic byproducts to carbon dioxide. Reaction pathways accounting for the formation of most observed products are proposed.

: Sutherland's theoretical expression for the absolute or dynamic viscosity of a gas has been modified to represent experimental viscosity data for air. The resulting semi-empirical equation accurately describes measured viscosities of air for temperatures ranging from the boiling point at 78 K to molecular dissociating conditions at 2500 K. Discrepancies between measured values and semi-empirical results rarely exceed 2%. Other more limited expressions for the viscosity of air are also compared to measured viscosity data and discussed. (Author)

Calixarenes are interesting building blocks in supramolecular receptor design. They can be easily functionalized to give the desired guest binding and sequestration properties. We demonstrate here the use of simple alkylated calixarenes as novel NO 2 sensors. Upon reacting with gaseous NO 2 , alkylated calixarenes form stable calixarene-NO + (nitrosonium) complexes that have a deep purple color. This specific and selective formation of the colored complex was used to develop a fiber optic based colorimetric NO 2 sensor. Several alkylated calixarenes are used and tested as sensing materials. The calixarene compound was immobilized on a fine mesh silica-gel coated thin layer chromatography plate. The sensing plate was coupled with a fiber optic based photodetector. Gas samples were sampled in a manner where they impinged on the surface of sensing plate. The light transmission through the plate was continuously monitored. For a 5 min sample, the limit of detection was 0.54 ppmv with 1,3-alternate O-hexyl calix[4]arene (1a). There were no significant response differences between different conformations of calixarenes such as 1,3-alternate or cone. This chemistry can form the basis of a colorimetric sensor that relies on extant filter tape technology.

The HOBAS aeration system was tested to compare changes in environmental and bacteriological parameters in ponds growing Penaeus monodon during a single production cycle. The stocking density in the aerated pond was doubled to 12 post-larvae (PL) m − 2 in contrast to the non-aerated pond with 6 (PL) m − 2. Microbial abundance in the ponds ranged between 105 − 6 cells ml − 1. Among the physiological groups of bacteria enumerated, the heterotrophs dominated with an abundance of 104 CFU ml − 1. Of the nitrogen and sulfur cycle bacteria, the nitrifiers flourished in the aerated pond and could maintain ammonia-N concentration within permissible levels. Bacterial activity also maintained sulfide concentrations at  − 1. Non-aerated conditions promoted denitrification maintaining nitrate concentration between 0.32 and 0.98 μM NO3  − -N l − 1. However, a marked increase in ammonium content was observed in the non-aerated pond at the end of the culture period. Thus in high-density ponds, the aerators served to stimulate bacterial growth and activity which consequently maintained the quality of the water to match that of low-density ponds. Accordingly, these aerators could be effectively used to sustain higher yields. The effluent from the aerated pond is less likely to alter the redox balance of the receiving waters.

Pressurised infusion devices may have only limited capability to detect and remove air during pressurised infusions. In order to assess pressure infusion systems with regard to their actual air elimination capabilities four disposable pressure infusion systems and fluid warmers were investigated: The Level 1Ò (L-1), Ranger Ò (RA), GymarÒ (GY), and the WarmfloÒ (WF). Different volumes of air were injected proximal to the heat exchanger and the remaining amount of air that was delivered at the end of the tubing was measured during pressurised infusions. Elimination of the injected air (100-200 ml) was superior by the RA system when compared to L-1 (p < 0.01). The GY and WF systems failed to eliminate the injected air. In conclusion, air elimination was best performed by the RA system. In terms of the risk of air embolism during pressurised infusions, improvements in air elimination of the investigated devices are still necessary.

Objectives. Our objective is to examine spatial relationships between modeled criteria air pollutants (i.e., nitrous oxides, carbon monoxide, and ozone) and sociodemographics in metropolitan Phoenix, Arizona. Modeled air pollution offers environmental justice researchers a new and robust data source for representing chronic environmental hazards. Methods. We used multiple regression equations to predict criteria pollution levels using sociodemographic variables at the Census block group level. Results. We find that Census block groups with lower neighborhood socioeconomic status, higher proportions of Latino immigrants, and higher proportions of renters are exposed to higher levels of criteria air pollutants. Proportion African American, however, is not a significant predictor of criteria air pollution in the Phoenix metro area. Conclusions. These findings demonstrate clear social-class and ethnic-based environmental injustices in the distribution of air pollution. We attribute these patterns to the role of white privilege in the historical and contemporary development of industrial and transportation corridors in Phoenix in relation to racially segregated neighborhoods. Although all people are implicated in the production of criteria pollutants, lower-income and ethnic-minority residents are disproportionately exposed in metropolitan Phoenix. This article examines the environmental justice implications of spatial relationships between modeled criteria air pollutants (nitrous oxides, carbon monoxide, and ozone) and sociodemographics in metropolitan Phoenix (Maricopa County). The use of modeled air pollution data offers environn Direct correspondence to Sara Grineski, Department of Sociology and Anthropology, University of Texas at El Paso, El Paso, TX 79968 hsegrineski@utep.edui. Sara Grineski will share all coding information and data with those wishing to replicate the study. We acknowledge the contributions of Dr. Yu-Jin Choi, an environmental engineer at Arizona State University. Dr. Choi shared her pollution models with us and patiently answered our questions about them. We also acknowledge the assistance of Carol Atkinson-Palombo and

Inversions of borehole temperature profiles that reconstruct past ground surface temperature (GST) changes have been used to estimate historical changes in surface air temperature (SAT). Paleoclimatic interpretations of GST reconstructions are based on the assumption that GST and SAT changes are closely coupled over decades, centuries, and longer. This assumption has been the subject of some debate because of known differences between GST and SAT at timescales of hours, days, seasons, and years. We investigate GST and SAT relationships on daily, seasonal, and annual timescales to identify and characterize the principal meteorological changes that lead to short-term differences between GST and SAT and consider the effects of those differences on coupling between the two temperatures over much longer time periods. We use observational SAT and subsurface data from Fargo, North Dakota; Prague, Czech Republic; Cape Henlopen State Park, Delaware; and Cape Hatteras National Seashore, North Carolina. These records comprise intradaily observations that span parts of one or two decades. We compare subsurface temperature observations to calculations from a conductive subsurface model driven with daily SAT as the surface boundary condition and show that daily differences exist between observed and modeled subsurface temperatures. We also analyze year-to-year spectral decompositions of daily SAT and subsurface temperature time series and show that dissimilarities between mean annual GST and SAT are attributable to differences in annual amplitudes of the two temperature signals. The seasonal partitioning of these amplitude differences varies from year to year and from site to site, responding to variable evapotranspiration and cryogenic effects. Variable yearto-year differences between mean annual GST and SAT are closely estimated using results from a multivariate regression model that associates the partial influences of seasonal meteorological conditions with the attenuation of annual GST amplitudes.

To Investigate the mechanisms of pulmonary gas-exchange Impairment In Idiopathic pulmonary fibrosis (IPF) and to evaluate their potential relationship to the CO diffusing capacity (OLeo), we studied 15 patients with IPF (mean OLeo, 52% of predicted) at rest (breathing room air and pure O2) and during exercise. We measured pulmonary hemodynamics and respiratory gasexchange variables, and we separated the ventilation-perfusion (VAQ) mismatching and O 2 diffusion limitation components of arterial hypoxemia using the multiple Inert gas elimination technique. At rest VAlQ mismatching was moderate (2 to 4% of cardiac output perfusing poorly or unventilated lung units), and 19% of AaPo 2 was due to O 2 diffusion limitation. During exercise VAlQ mismatch did not worsen but the diffusion component of arterial hypoxemia Increased markedly (40% AaPo 2 , p < 0.005). We observed that those Patients with higher pulmonary vascular tone (more release of hypoxic pulmonary vasoconstriction) showed less pulmonary hypertension during exercise (p < 0.05), less VAlQ mismatching [at rest (p < 0.005) and during exercise (p < 0.0025)], and higher arterial p0 2 during exercise (p = 0.01). We also found that OLeo corrected for alveolar volume (KeO) correlated with the mechanisms of hypoxemia during exercise [VAlQ mismatching (p < 0.025) and O 2 diffusion limitation (p < 0.05)] and with the Increase In pulmonary vascular resistance elicited by exercise (p < 0.005). In conclusion, we showed that the abnormalities of the pulmonary vasculature are key to modulate gas exchange In IPF,especially during exercise. We recommend the routine correction of DLeo for alveolar volume (KeO) In the clinical a_88ment of patients with IPF because the latter seems to be a useful functional Indicator of both the severity of gas-exchange Impairment during exercise and the degree of pulmonary vascular Involvement.

Seasonal fluctuations in the methane fluxes in the soil-atmosphere system were determined for gray forest soils of Central Russia. Consumption of atmospheric methane was found to exceed methane emission in gray forest soils under forest and in the agrocenosis. The average annual rates of atmospheric methane consumption by the soil under forest and in the agrocenosis were 0.026 and 0.008 mg C-CH 4 /(m 2 h), respectively. The annual rate of atmospheric methane oxidation in the gray forest soils of Moscow oblast was estimated to be 0.68 kton. Seasonal fluctuations in the methane oxidation activity were due to changes in the hydrothermal conditions and in the reserves of readily decomposable organic matter and mineral nitrogen, as well as to changes in the activity of methane oxidizers.

The American Conference of Governmental Industrial hygienists (ACGIH) lowered the threshold limit value (TLV) for respirable crystalline silica (RCS) exposure from 0.05 to 0.025 mg m 23 in 2006. For a working environment with an airborne dust concentration near this lowered TLV, the sample collected with current standard respirable aerosol samplers might not provide enough RCS for quantitative analysis. Adopting high flow rate sampling devices for respirable dust containing silica may provide a sufficient amount of RCS to be above the limit of quantification even for samples collected for less than full shift. The performances of three high flow rate respirable samplers (CIP10-R, GK2.69, and FSP10) have been evaluated in this study. Eleven different sizes of monodisperse aerosols of ammonium fluorescein were generated with a vibrating orifice aerosol generator in a calm air chamber in order to determine the sampling efficiency of each sampler. Aluminum oxide particles generated by a fluidized bed aerosol generator were used to test (i) the uniformity of a modified calm air chamber, (ii) the effect of loading on the sampling efficiency, and (iii) the performance of dust collection compared to lower flow rate cyclones in common use in the USA (10-mm nylon and Higgins-Dewell cyclones). The coefficient of variation for eight simultaneous samples in the modified calm air chamber ranged from 1.9 to 6.1% for triplicate measures of three different aerosols. The 50% cutoff size ( 50 d ae ) of the high flow rate samplers operated at the flow rates recommended by manufacturers were determined as 4.7, 4.1, and 4.8 mm for CIP10-R, GK2.69, and FSP10, respectively. The mass concentration ratio of the high flow rate samplers to the low flow rate cyclones decreased with decreasing mass median aerodynamic diameter (MMAD) and high flow rate samplers collected more dust than low flow rate samplers by a range of 2-11 times based on gravimetric analysis. Dust loading inside the high flow rate samplers does not appear to affect the particle separation in either FSP10 or GK2.69. The high flow rate samplers overestimated compared to the International Standards Organization/ Comité Européen de Normalisation/ACGIH respirable convention [up to 40% at large MMAD (27.5 mm)] and could provide overestimated exposure data with the current flow rates. However, both cyclones appeared to be able to provide relatively unbiased assessments of RCS when their flow rates were adjusted.

Background. Intussusception remains a frequent cause of bowel obstruction in children and typically is treated by reduction via enema. Controversy persists regarding the optimal reduction technique to maximize success while minimizing morbidity. Methods. We reviewed our institutional data comparing outcomes of enema reduction that use contrast medium versus air. A systematic review also was undertaken of comparative studies evaluating pneumatic (oxygen or air) versus hydrostatic (any contrast medium) reduction. Critical appraisal was performed with the Methodological Index for Non Randomized Studies scale for observational studies, Jadad score for randomized trials. Meta-analysis was performed with REVMAN 5.1. Results. Institutional data revealed a failed reduction rate of 20.4% (20/98) with air and 29.6% (8/27) with contrast reduction. Nineteen studies were included in the systematic review. The cumulative failure rate favored pneumatic reduction (odds ratio [OR] 0.45; 95% confidence interval [95% CI] 0.34-0.60); sensitivity analysis of prospective studies demonstrated similar results (OR 0.39; 95% CI 0.24-0.63). The number needed to treat to eliminate one failed reduction was nine pneumatic reductions. No difference was noted in reported perforations (OR 0.98; 95% CI 0.48-2.03). Conclusion. Pneumatic reduction is more likely to successfully reduce intussusception in children without evidence of increased morbidity. In the context of available expertise, pneumatic reduction should be the method of choice for the treatment of intussusception barring an indication for immediate operative intervention. (Surgery 2013;154:328-34.)

Laboratory-accelerated ageing tests have been conducted to examine the depletion of antioxidants from highdensity polyethylene (HDPE) geomembranes as a result of their exposure to various environments. Samples of 2.0 mm thick geomembrane were exposed to air, water, and municipal solid waste (MSW) leachate at temperatures of 22, 40, 55, 70, and 85°C. At various time intervals, samples were collected and the oxidative induction time (OIT) was evaluated. The results indicated that the antioxidants are depleted at rates 1.6 to 2.4 times faster for samples in water than for air-exposed samples. For samples in leachate, the depletion is about 4 times faster than that in air and 1.6-3.2 times faster than that in water. Using these rates, it is estimated that if the geomembrane examined were used as an MSW landfill primary liner, it would take at least 40 years to deplete the antioxidants from the geomembrane at a temperature of 33°C and over 150 years at a temperature of 13°C.

This study demonstrated the microbial purification of a model wastewater containing 2,4,6-trinitrophenol (TNP), which was carried out in a continuously working biological aerated filter (BAF). The main emphasis was on the operating performance of the reactor as a function of the pollution load. TNP was degraded at a maximum volumetric removal rate of 2.53 g TNP/L d, with low residual COD and TNP concentration. Overloading of TNP inhibited the nitrite-oxidizing activity, resulting in poor TNP degradation performance in the BAF system. The inhibition depended on some factors, such as influent concentrations and flow rates of the influent. It is assumed that nitrite-oxidizing occurred spontaneously during TNP degradation in the BAF system, could have significant influence on TNP wastewater treatment. One year after the reactor start-up, the dominance of Rhodococcus, which was initially inoculated in the reactor, was confirmed by analysis of 16S rDNA sequence of the PCR products separated by DGGE.

To determine the efficacy of an in-office desensitizing paste containing 8% arginine and calcium carbonate relative to that of a commercially-available pumice prophylaxis paste in reducing dentin hypersensitivity instantly after a single application following a dental scaling procedure and to establish the duration of sensitivity relief over a period of 4 weeks and 12 weeks. This was a single-center, parallel group, double-blind, stratified clinical study conducted in San Francisco, California, USA. Qualifying adult male and female subjects who presented two hypersensitive teeth with a tactile hypersensitivity score (Yeaple Probe) between 10-50 grams of force and an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were stratified according to their baseline hypersensitivity scores and randomly assigned within strata to one of two treatment groups: (1) A Test Paste, a desensitizing paste containing 8% arginine and calcium carbonate (Colgate-Palmolive Co)...

Plasma treatment is a promising technology for fast and effective sterilization of surfaces, waterflow, and airflow. The treatment of airflow is an important area of healthcare and biodefense that has recently gained the interest of many scientists. In this paper, we describe a dielectric barrier grating discharge (DBGD) which is used to study the inactivation of airborne Escherichia coli inside a closed air circulation system. Earlier published results indicate approximately 5-log reduction (99.999%) in the concentration of the airborne bacteria after single DBGD exposure of 10-s duration. This paper investigates plasma species influencing the inactivation. The two major factors that are studied are the effect of charged and short-lived species (direct exposure to plasma) and the effect of ozone. It is shown that for a 25% reduction in direct exposure, the inactivation falls from 97% to 29% in a single pass through the grating. The influence of ozone was studied by producing ozone remotely with an ozone generator and injecting the same concentration into the system, as that produced by the DBGD plasma. The results show a 10% reduction in the bacterial load after 10-s exposure to ozone; thus, ozone alone may not be one of the major inactivating factors in the plasma.

A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with carbon nanotubes (CNTs) and catechol compounds. First, 25 μL of DMSO–CNTs solutions (0.4 mg/mL) was cast on the surface of GC electrode and dried in air to form a CNTs film. Then the GC/CNTs modified electrode immersed into a chlorogenic acid, catechine hydrate and caffeic acid solution (electroless deposition) for a short period of time (2–80 s). The cyclic voltammogram of the modified electrode in aqueous solution shows a pair of well-defined, stable and nearly reversible redox couple (quinone/hydroquinone) with surface confined characteristics. The combination of unique electronic and electrocatalytic properties of CNTs and catechol compounds results in a remarkable synergistic augmentation on the response. The electrochemical reversibility and stability of modified electrode prepared with incorporation of catechol compound into CNTs film was evaluated and compared with usual methods for attachment of catechols to electrode surfaces. The transfer coefficient (α), heterogeneous electron transfer rate constants (ks) and surface concentrations (Γ) for GC/CNTs/catechol compound modified electrodes were calculated through the cyclic voltammetry technique. The modified electrodes showed excellent catalytic activity, fast response time and high sensitivity toward oxidation of hydrazine in phosphate buffer solutions at pH range 4–8. The modified electrode retains its initial response for at least 2 months if stored in dry ambient condition. The properties of modified electrodes as an amperometric sensor for micromolar or lower concentration detection of hydrazine have been characterized.

Cracks and channels in cement often create unwanted conduits behind casing that lead to crossflow between different producing zones. Crossflow results in lost production or aquifer contamination because fluid flows from a higherpressure to a lower-pressure zone instead of traveling up the well. We present measurements of acoustic signatures of crossflow behind the pipe in time and frequency domains. Despite being called "noise," they are shown to be propagating tube waves with impulsive signatures. When multiple crossflow locations are present along the well, these signatures are unique for each location and are highly repeatable. We observe time-lapse change in such signatures during air injection and release and suggest that these changes can be used for real-time acoustic characterization of depletion in stacked commingled reservoirs. We anticipate that such signals are typical for commingled production of multilayered reservoirs. Acoustic signatures can be used to characterize crossflow and depletion. In addition, crossflow signals represent a strong noise affecting downhole seismic surveillance with active sources.

An experimental investigation on natural convection in air in vertical convergent channels with wall uniform heat flux is presented. Wall temperatures show that by increasing the spacing the effect of the convergence angle decreases. For the lowest spacing, a significant decrease of maximum wall temperature occurs passing from the parallel vertical plate configurations to convergence angles h P 2 .

East Orange and Newark, N.J. Purpose: Calf muscle pump dysfunction is a recognized factor in chronic venous insufficiency (CVI). We investigated the hypothesis that limbs with CVI have a reduced ankle range of motion (ROM) that may be responsible for the poor calf pump function associated with venous ulceration.

Two formal validation studies of the Air Traffic Control Specialist Pre-Training Screen (ATCS/PTS), a 5-day computer-administered test battery, are described. The ATCS/PTS was designed to replace the 9-week U.S. Federal Aviation Administration (FAA) Academy ATCS Nonradar Screen program that served as the second major test in the ATCS selection system. Review of ATCS job analyses suggested that predictor tests should assess cognitive constructs such as spatial reasoning and short-term memory, and require dynamic, concurrent performance. A proposed test battery was developed, consisting of 2 computeradministered information processing tests and a simplified radar-based air traffic control work sample. In study 1, predictive, criterion-related validation (N = 438) found that the proposed test battery explained additional variability in scores earned in the 9-week FAA Academy program, after taking into account student aptitude. In study 2, criterion-related validation (N = 297) demonstrated that the proposed test battery was as valid as the 9week FAA Academy ATCS Nonradar Screen for predicting progress in field training. Preliminary data from a third study conducted after validation of the ATCSIPTS seem to suggest that the abilities assessed by the new computerized tests reflect the abilities required on the job. However, implementation of the ATCS/PTS for actual employment decisionmaking in June 1992 was based on results obtained in the second concurrent, criterion-related validation study. The U.S. controller selection system since June 1992 has consisted of the 4-hour written ATCS aptitude test battery followed by, for those applicants earning a qualifying score and dependent upon agency manpower requirements, secondlevel screening on the ATCS/PTS. Additional research requirements as part of an aviation human factors research program are described.

In the present study, we have characterized in detail the MS 2 and MS 3 fragmentation behaviors, using electrospray ionization (ESI) in the negative ion mode, of previously identified sulfated isoprene secondary organic aerosol compounds, including 2-methyltetrols, 2-methylglyceric acid, 2-methyltetrol mononitrate derivatives, glyoxal and methylglyoxal. A major fragmentation pathway for the deprotonated molecules of the sulfate esters of 2-methyltetrols and 2-methylglyceric acid and of the sulfate derivatives of glyoxal and methylglyoxal is the formation of the bisulfate [HSO 4 ] − anion, while the deprotonated sulfate esters of 2-methyltetrol mononitrate derivatives preferentially fragment through loss of nitric acid. Rational interpretation of MS 2 , MS 3 and accurate mass data led to the structural characterization of unknown polar compounds in K-puszta fine aerosol as organosulfate derivatives of photooxidation products of unsaturated fatty acids, i.e. 2-hydroxy-1,4-butanedialdehyde, 4,5-and 2,3-dihydroxypentanoic acids, and 2-hydroxyglutaric acid, and of a-pinene, i.e. 3-hydroxyglutaric acid. The deprotonated molecules of the sulfated hydroxyacids, 2-methylglyceric acid, 4,5-and 2,3-dihydroxypentanoic acid, and 2-and 3hydroxyglutaric acids, showed in addition to the [HSO 4 ] − ion (m/z 97) neutral losses of water, CO 2 and/or SO 3 , features that are characteristic of humic-like substances. The polar organosulfates characterized in the present work are of climatic relevance because they may contribute to the hydrophilic properties of fine ambient aerosol. In addition, these compounds probably serve as ambient tracer compounds for the occurrence of secondary organic aerosol formation under acidic conditions.

This study evaluates the efficiency of fluid-air exchange on the reattachment of the retina and clarifies the possibility that a posterior retinotomy is a cause for intra- and postoperative complications. A consecutive series of 211 eyes with retinal detachments due to P.V.R. (47%), diabetic traction, perforating trauma, macular hole or giant tears is presented. All eyes underwent pars plana vitrectomy, fluid-air exchange, internal drainage of subretinal fluid, laser endophotocoagulation and scleral buckling of the tears; 56% of the eyes were phakic and 55% underwent a posterior retinotomy, 54% underwent tamponade with C3F8 and 46% with silicone oil. Intraoperatively the retina was completely flattened in 91% cases. The causes of incomplete reattachment were residual membranes (6.6%), poor visualization (1.4%) and suprachoroidal hemorrhage (1%). These complications were isolated as being the cause of the bad final results (p < 0.001). Postoperatively, the retina remained attached in 66% of cases after the first procedure and with further surgery in 81% (mean follow up 16 months). Best corrected visual acuity was improved in 73% of eyes, unchanged in 17%, and worse in 10%. Complications were retraction of the retinotomy site in 3 cases and peripheral choroidal hemorrhage in 4 cases. We concluded that fluid air exchange with internal subretinal fluid drainage was an efficient and safe technique even if a posterior retinotomy was necessary.

Aim: To characterize the development of clinically relevant variables the first minutes after birth and identify early prognostic markers in newborn infants requiring resuscitation. Methods: A database of 591 infants resuscitated with either 21% or 100% oxygen was analysed. Time to first breath, development in heart rate, Apgar scores, arterial oxygen saturation (SaO 2 ), and base deficit (BD) are described in relation to different degrees of birth depression and outcomes. Results: Heart rate and Apgar scores increased quickly even in the most depressed infants but were significantly lower in those having a poor outcome. By contrast, BD normalized at the same rate, 6-7 mmol/l/h, in the first hour of life regardless of the degree of birth depression and outcome. SaO 2 values increased as quickly in room air as in 100%-oxygen-resuscitated infants. Time to first breath was prolonged threefold, from 1 to 3 min, in the most depressed (1-min Apgar score 54) compared with the less depressed infants. Highest odds ratio (OR) for death in the first week of life or for development of hypoxic-ischaemic encephalopathy (HIE) stage 2 and 3 was a 5-min heart rate 460 bpm (OR 16.5 for both death and HIE) and Apgar 54 (OR 14 and 18.8). Neonatal survival for HIE stage 1, 2, and 3 was 93%, 63%, and 11%, respectively. OR for early neonatal death, if SaO 2 460% at 1 min, was 8.6 (sensitivity 0.82 and specificity 0.65).

The present study was designed to compare the electrophysiological characteristics of the principalis, oralis and interpolaris nuclei of the trigeminal sensory complex under stimulation of the vibrissae by air puffs. This stimulus generates deflection profiles resembling those induced by contact with real objects in natural conditions. Three populations of neurons were identified in each nucleus according to their mean spiking frequency at rest. The three nuclei differed in terms of their mean spiking frequencies, the response latencies of their neurons and the proportions of each neuron population observed in single and multi-unit recordings. Findings suggest different information processing tasks for each nucleus.

The snorkel, which allows swimmers to keep their face down in the water while breathing, is widely used by divers, spear fishermen and monofin swimmers. A snorkel consists of a mouthpiece and a tube that has an air space usually with a volume of 160 ± 170 ml. This volume functions as an additional dead space in addition to the anatomical dead space, because the air in the snorkel is re-inspired. The concentration of CO 2 in the gas in the snorkel will be equal to expired air, since expired air is trapped in the snorkel tube. Some monofin swimmers reported that they felt their performance was better when they expired into the water instead of expiring into the snorkel, thus ensuring that the inspired air in the snorkel has no expired CO 2 in it. An increase in ventilation is expected when the concentration of CO 2 is higher in the inspired gas and this has been shown in several studies . In this paper we investigated ventilatory response and metabolic changes when rebreathing the gas in the snorkel.

A report is given on the ionization/dissociation behavior of the title compounds within air plasmas produced by electrical corona discharges at atmospheric pressure: both positive and negative ions were investigated at different temperatures using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). CHF(2)CH(3) (HFC-152a) undergoes efficient ionic oxidation to C(2)H(5)O(+), in which the oxygen comes from water present in the plasma. In contrast, CF(3)CH(2)F (HFC-134a) does not produce any characteristic positive ion under APCI conditions, its presence within the plasma being revealed only as a neutral ligand in ion-molecule complexes with ions of the background (H(3)O(+) and NO(+)). Analogously, the perfluorocarbon FC-72 (n-C(6)F(14)) does not produce significant positive ions at 30 degrees C: at high temperature, however, it undergoes dissociative ionization to form many product ions including C(3)F(6)(+), C(2)F(4)(+), C(n)F(2n+1)(+) and a few families of oxygen co...