Laccase initiated oxidative domino reactions for the efficient synthesis of 3,4-dihydro-7,8-dihydroxy-2H-dibenzofuran-1-ones

Laccase initiated domino reactions of cyclohexane-1,3-diones with catechols using air as an oxidant afford 3,4-dihydro-7,8-dihydroxy-2H-dibenzofuran-1-ones with yields ranging from 70% to 97%.     

气垫船稳态船波势及波阻的边界元法

本文给出了气垫船在静水中航行时稳态船波势问题的边界元数值分析方法，根据本文的数值计算方法，可以得到气垫船行时所兴起的波浪形状以及气垫附近流场情况，由此可计算气垫所受到的兴波阻力，本文的方法适用于任意已知气压分布情况。     

Boundary layer parametrization for atmospheric diffusion models by meteorological measurements at ground level

Summary Over recent years several theoretical and experimental works have made it possible to evaluate the basic parameters describing the atmospheric boundary layer by means of elementary meteorological measurements in proximity to the ground. This has opened up the possibility of utilizing atmospheric pollutant dispersion models able to use direct evaluations of atmospheric turbulence through friction velocity and the Monin-Obukhov length. The present paper provides an application of these new techniques in the Milan area.     

CO2 dial for monitoring atmospheric pollutants at the University of Calabria

Summary In this report we introduce the infrared lidar-dial apparatus developed at the University of Calabria. It has been carried out as a tool in the investigation of both the atmospheric pollution of trace gases and other atmospheric parameters as water vapour. The general scheme of the station is described, as well as the performances of the home-made CO₂ laser sources. Finally preliminary measurements of average concentration of ozone and water vapour over a range of about 3 km are presented and discussed in the report.     

Solar-microclimate study in urban areas

Summary A study on solar microclimates in eight medium and large European cities, supported by EEC from 1986 to 1988, could allow to mark the main resemblances and anomalies in the solar-radiation features in different geographical and climatic regions in Northern, Central and Southern Europe and also to achieve reliable estimates of available energy in thermal-conversion processes of solar radiation. This paper presents the results of an analysis of solar-radiation observations taken during the EEC study and discusses the main solar climatic peculiarities of the urban area of Turin (one of the eight cities involved in this project), comparing them to other European regions (south and north of Turin).     

Spatial inhomogeneity of anions in ambient particulate matter collected on air filters: determination using a drift-corrected ion chromatography technique

The spatial inhomogeneity of anions in ambient particulate matter collected on filters has been investigated using two different sub-sampling techniques and with analysis by a drift-corrected ion chromatography technique. The results highlight the inhomogeneity in anion mass along the radius of the sampled filter, in agreement with analogous studies on metals in PM, and also, more surprisingly, significant random differences between sub-samples based on filter sectors. Implications for the sub-sampling of filters for the purposes of performing multiple analyses are discussed.     

Detection of cocaine in the airborne particles of the Italian cities Rome and Taranto

Cocaine was first detected in the air of two Italian cities, Rome and Taranto, where it reached concentrations sometimes exceeding 100 pg/m(3), by HRGC-MS analysis of carbonaceous aerosol samples. By contrast, the drug was virtually absent in Algiers (Algeria). In Italy, atmospheric concentrations of cocaine were, on average, similar to those of other toxic pollutants like polychlorobiphenyls or nitrated polynuclear aromatic hydrocarbons, and higher than those of polychlorodibenzo-p-dioxins/polychlorodibenzofurans. The cocaine concentrations seemed to correlate with regional consumption of the drug in Rome and Taranto. By contrast, it correlated neither with nicotine or caffeine, nor with benzo[a]pyrene, the sole organic compound associated with aerosols that is quoted according to Italian legislation.     

The use of multi-channel silicone rubber traps as denuders for polycyclic aromatic hydrocarbons

Atmospheric polycyclic aromatic hydrocarbons are ubiquitous environmental pollutants, which may be present both in the gaseous phase and adsorbed onto the surface of particles. Denuders are sampling devices which have been effectively employed in such partitioning applications. Here we describe and characterise a novel miniature denuder consisting of two multi-channel silicone rubber traps (each 178 mm long, 6 mm o.d. containing 22 silicone tubes), separated by a quartz fibre filter for particle phase collection. The denuder only requires a small portable personal sampling pump to provide sampling flow rates of ∼0.5 L min⁻¹. Theoretical considerations indicated that the air flow through the denuder was expected to be laminar, and the linear velocity arising from longitudinal diffusion was found to be negligible. The calculated particle transmission efficiency through the denuder was found to be essentially 100% for particles > 50 nm, whilst the experimental overall efficiency, as determined by CPC and SMPS measurements, was 92 ± 4%. The size resolved transmission efficiency was <60% for particles below 20 nm and 100% for particles larger than 200 nm. Losses could have been due to diffusion and electrostatic effects. Semi-volatile gaseous analytes are pre-concentrated in the silicone of the trap and may be thermally desorbed using a commercially available desorber, allowing for total transfer and detection of the collected analytes by GC–MS. This enhances detection limits and allows for lower sampling flow rates and shorter sampling times, which are advantageous for studies requiring high temporal resolution.     

Determination of Benzo(a)Pyrene and other Polynuclear Aromatic Hydrocarbons in Airborne Particulate Material by Ultrasonic Extraction and Reverse Phase High Pressure Liquid Chromatography

Abstract

Ultrasonic extraction of airborne particulate material on Hi-Vol filters is described. Almost all of the polar compounds are removed during the extraction by adsorption on the surface of the shredded glass fibers and controlled pore glass powder (CPG). The non-polar polynuclear aromatic hydrocarbons (PAH) in the extract are separated at room temperature by high pressure liquid chromatography (HPLC) on reverse phase Vydac using acetonitrile:water (70:30 v/v) as the chromatographic solvent. There is baseline separation of benzo(a)pyrene (BaP), benzo(k)fluoranthene (BkFt) and of benzo(e)pyrene (BeP), benzo(b)fluoranthene and perylene, the latter three present in one band. Extracts of airborne particulates show the same peaks. BaP elutes in approximately 14 minutes. Precision and accuracy measurements indicate full recovery of PAH and good extraction reproducibility. The detection limit of BaP at F 290/389 is less than 10 pg. Total analysis time is approximately 1 1/2 hr, most of which is waiting time.