Graphitized Carbon Black in Quartz Tubes for the Sampling of Indoor Air Nicotine and Analysis by Microwave Thermal Desorption—Capillary Gas Chromatography

Nicotine in a smoky indoor air environment can be determined using graphitized carbon black as a solid sorbent in quartz tubes. The temperature stability, high purity, and heat absorption characteristics of the sorbent, as well as the permeability of the quartz tubes to microwaves, enable the thermal desorption by means of microwaves after active sampling. Permeation and dynamic dilution procedures for the generation of nicotine in the vapor phase at low and high concentrations are used to evaluate the performances of the sampler. Tube preparation is described and the microwave desorption temperature is measured. Breakthrough volume is determined to allow sampling at 0.1-1 L/min for definite periods of time. The procedure is tested for the determination of gas and paticulate phase nicotine in sidestream smoke produced in an experimental chambe

Exposition professionnelle aux hydrocarbures aromatiques polycycliques (HAP) dans la poussière de bois chez les ponceurs de parquet

Préambule Les tumeurs malignes des cavités naso-sinusiennes (CNS) représentent environ 3% des cancers ORL. L'adénocarcinome des CNS est une maladie professionnelle admise chez certains travailleurs spécialisés tels les menuisiers et les ébénistes. La Grande Bretagne en 1969 et la France en 1981 reconnaissent son étiologie professionnelle en se fondant sur des constats statistiques. La forte proportion de travailleurs du bois développant un adénocarcinome des CNS, dont le risque encouru est estimé de 50 à 1000 fois supérieur à celui de la population générale, a suggéré à certains auteurs divers pistes, tel que le tanin pour les bois durs, le formaldéhyde pour les contre-plaqués et le benzo(a)pyrène produit par le bois surchauffé. Les travaux spécifiques, tels que le ponçage, provoquent l'émission de poussières fines pouvant rester des heures en suspension dans l'air, surtout dans des endroits mal ventilés. Jusqu'à présent, de telles hypothèses n'ont pas été confirmées par des mesures pratiques, et le problème reste ouvert. Il est reconnu que le tanin ne provoque pas de cancer dans l'exposition à la poussière de thé. Le formaldéhyde est un irritant mais il est aussi classé cancérogène. La piste des hydrocarbures aromatiques polycycliques (HAP) cancérogènes provoqués par le bois surchauffé est séduisante. Nous avons étudié leur teneur en fonction des opérations pratiquées sur le bois en cabine d'expérimentation et mesuré la distribution granulométrique des poussières générées. Expériences Prélèvement de poussière de bois Les poussières de bois sont captées à 2 l/min par des filtres en fibre de verre (Ø 37 mm, GF/B, Whatman), préalablement conditionnés à humidité constante 55% RH dans une boîte à gants. Détermination granulométrique des particules de bois et analyse des HAP Un impacteur de particules (Ambient Particle Sizing Sampler, Andersen Inc.) muni de filtres en fibre de verre est utilisé pour la captation et la pesée de la poussière en fonction de la granulométrie des particules. Pour étudier la répartition granulométrique des particules de bois en fonction des opérations telles que le sciage, le rabotage ou le ponçage, nous avons simulé ces opérations dans notre cabine d'expérimentation de 10 m3 de volume. Les matériaux testés sont du sapin brut, du chêne et chêne imprégné de polyuréthane. Les HAP sont analysés par HPLC et détection par fluorescence. Résultats La poussière de bois contient des HAP au niveau du μg/g ou ppm. Le bois imprégné de vernis PU produit 100 fois plus de HAP que le bois brut lors des opérations de ponçage. Les instruments de travail du bois tels que ponceuse, scie circulaire ou raboteuse génèrent des poussières dont la granulométrie est centrée sur 10 μm ou plus, d'où un dépôt prépondérant de poussière dans la cavité naso-sinusienne et moins dans le poumon. La norme 2 mg/m3 de poussière totale semble protéger efficacement les travailleurs, pour autant que les teneurs en HAP ne dépassent pas le niveau du ppm. Il est important que les travailleurs concernés prennent conscience du danger de l'exposition à la poussière de bois et qu'ils adoptent des mesures de protection adéquates, comme le port de masque à poussière ou la ventilation du local. Les outils équipés de sac à poussière engendrent moins de poussière dans l'air et contribuent à une meilleure protection. L'adénocarcinome des CNS chez les menuisiers et les ébénistes pourrait-il être expliqué par la présence des HAP dans la poussière de bois

Improvement of Tuning Fork Gyroscope Drive-mode Oscillation Matched using a Differential Driving Suspension Frame

This paper presents a novel design of a vibration tuning fork gyroscope (TFG) based on a differential driving suspension coupling spring between two gyroscopes. The proposed TFG is equivalent to a transistor differential amplifier circuit. The mechanical vibrations of driving frames are, therefore, well matched. The matching level depends on stiffness of spring. When three various TFG structures respond to differential stiffness of spring, their the driving frame mechanical vibration is well matched in case the input excitation driving differential phase is less than 3.5°, 2.5°, and 4°, respectively. The fabricated tuning fork gyroscope linearly operates in the range from -200 to +200 degree/s with the resolution of about 0.45 mV/degree/s

Mechanical response of outer frames in tuning fork gyroscope model with connecting diamond-shaped frame

In tuning fork micro-gyroscopes, two outer frames are connected by using the linking elements. The driving vibrations of the two outer frames are required to be exactly opposite to generate the opposite sensing modes perpendicular to driving direction. These opposite driving vibrations are provided by a mechanical structure named the diamond-shaped frame. This paper presents mechanical responses of two outer frames in a proposed model of tuning fork gyroscope when an external force with different types is applied to them. The results show that the presence of a diamond-shaped frame guarantees the absolute anti-phase mode for the driving vibrations of outer frames

Laboratory generated bitumen fumes under standardized conditions and emission levels for VOC, semi-volatile and particulate PAH and PASH. Ion trap GC-MS analytical method development and clean-up scheme

Concern regarding the hazardous health effects from exposure to chemicals in bitumen fumes has been expressed and there are a great deal of interests for data on profile of individual compounds in the gas and particulate phases. The purpose of the study was to evaluate a method for the determination of volatile organic compounds (VOC), semi-volatile and particulate polycyclic aromatic compounds (PAH) and sulfur polyheterocylic (PASH) compounds in bitumen fumes. The methylated derivatives of PAH are of particular interest since many of them exhibit carcinogenic activities while the parent compound does not. Bitumen fumes were laboratory generated at 170°C using a fume generator with controlled characteristics. Sampling of bitumen fumes was carried out with XAD-2 Orbo tubes for the gas phase chemicals and semivolatile PAH or PASH. Glass Fiber GF/B were used to sample the fumes aerosol particulates at a flow rate of 1.2 L/min PAH profiles and PASH in bitumen fumes were determined by GC-MS further to a multi-step sample treatment and automatic clean-up procedure. The internal standard was added to 0.1 to 0.3 g of raw bitumen or bitumen fumes filter samples which were then extracted twice with 25 mL toluene by sonication for 10 min each. The reduced extract was partitioned between cyclohexane and dimethylformamide before elution on a SiO2 micro column. The eluent was reduced and fractionated by HPLC. The PAH fraction of interest which also contained PASH was separated by capillary column GC-ion trap MS using the single ion storage mode for optimized sensitivity. Quantification was made relative to the respective calibration curves between compounds of interest and the internal standard. The semi-volatile SVPAH and SVPASH were determined by separate desorption of the two distinct parts of the XAD-2 by 5mL CS2 and sonication for 30 min. Microliters of the combined filtered extract were then injected into a GC column and quantified by ion trap MS. Standard reference compounds were used for comparisons of respective spectra. Summary of results VOC: Aliphatic alkanes from C6 to C17 amount to several hundreds mg per equivalent gram of particulate fumes collected on the filter. Most of the other volatile present are benzene derivatives and total VOC amounts to 42 mg/g of fumes. Surprisingly, no benzene was detected in all the samples. PAH: Methylnaphthalene substitutes are quantitatively predominant. The well known trend is observed with light semi-volatile PAH found mainly in the gas phase. The trend is being reversed in the particulate phase from the methylphenanthrene and the four ring PAH to heavier molecular weight PAH. The naphthalene and its derivatives account for 93% of the total (both gas and particulate) PAH from 2 to 7 ring PAH. Methylchrysene derivatives are at higher levels than benzo[a]pyrene (BaP) in the fumes. The 6-7 rings PAH are not detected. PASH: The carcinogenic benzo[b]naphtho[2,1-d]thiophene is found in the fumes in higher amount than its two other isomers but less than the predominant dibenzothiophene. The sum dibenzonaphthothiophenes represents 16% of PASH analysed in the filter, gas phase not included. In conclusion, our analytical procedure is valid and robust enough for the determination of PASH and PAH in bitumen fumes with a relatively low uncertainty (<35% for light PAH and < 15% for higher MW PAH. New data are now available with the numerous methylnaphthalene derivatives and methylchrysene derivatives. VOC data and profile may be of interest for the interpretation of irritation effect The data may be useful for emission modelling purposes

Laboratory generated bitumen fumes under standardized conditions and emission levels for VOC, semi-volatile and particulate PAH and PASH: ion trap GC-MS analytical method development and clean-up scheme

Concern regarding the hazardous health effects from exposure to chemicals in bitumen fumes has been expressed and there is a great deal of interest for data on profile of individual compounds in the gas and particulate phases. The purpose of the study was to evaluate a method for the determination of volatile organic compounds (VOC), semi-volatile and particulate polycyclic aromatic compounds (PAH) and sulfur poly-heterocylic (PASH) compounds in bitumen fumes. The methylated derivatives of PAH are of particular interest since many of them exhibit carcinogenic activities while the parent compound does not. Bitumen fumes were laboratory generated at 170°C using a fume generator with controlled characteristics. Sampling of bitumen fumes was carried out with XAD-2 Orbo tubes for the gas phase chemicals and semi-volatile PAH or PASH. Glass Fiber GF/B were used to sample the fumes aerosol particulates at a flow rate of 1.2 L/min. PAH profiles and PASH in bitumen fumes were determined by GC-MS further to a multi-step sample treatment and automatic clean-up procedure. The internal standard was added to 0.1 to 0.3 g of raw bitumen or bitumen fumes filter samples which were then extracted twice with 25 mL toluene by sonication for 10 min each. The reduced extract was partitioned between cyclohexane and dimethylformamide before elution on a SiO2 micro column. The eluent was reduced and fractionated by HPLC. The PAH fraction of interest which also contained PASH was separated by capillary column GC-ion trap MS. Quantification was made relative to the respective calibration curves between compounds of interest and the internal standard. The semi-volatile SVPAH and SVPASH were determined by separate desorption of the two distinct parts of the XAD-2 by 5mL CS2 and sonication for 30 min. Microliters of the combined filtered extract were then injected into a GC column and quantified by ion trap MS. Standard reference compounds were used for comparisons of respective spectra. The purified extract enables the determination of PAH profile from 2 to 7 rings including their methyl derivatives and 3 carcinogenic benzonaphthothiophene isomers. The reproducibility of the method was estimated by analyzing 6 bitumen replicates and is around the 30% overall uncertainty or less. In bitumen fumes generated at 170°C under standardized conditions, VOC and semi-volatile PAH were sampled with XAD-2 tubes and were also determined in six replicates. The VOCs are mainly monoaromatic derivatives (4% of fumes) and aliphatics essentially from C6 to C17 (27%). With regards to the particulate phase PAC, the coefficients of variation from 6 replicates are 5-24 % for PAH and 6-10% for PASH. Data on VOC and PASH represent new contribution in the characterization of bitumen fumes

Sub-optimal Deep Pipelined Implementation of MIMO Sphere Detector on FPGA

Sphere detector (SD) is an effective signal detection approach for the wireless multiple-input multiple-output (MIMO) system since it can achieve near-optimal performance while reducing significant computational complexity. In this work, we proposed a novel SD architecture that is suitable for implementation on the hardware accelerator. We first perform a statistical analysis to examine the distribution of valid paths in the SD search tree. Using the analysis result, we then proposed an enhanced hybrid SD (EHSD) architecture that achieves quasi-ML performance and high throughput with a reasonable cost in hardware. The fine-grained pipeline designs of 4 × 4 and 8 × 8 MIMO system with 16-QAM modulation delivers throughput of 7.04 Gbps and 14.08 Gbps on the Xilinx Virtex Ultrascale+ FPGA, respectively

Quality Challenges of the Chemical Analyses in Occupational Health

Much emphasis is put on the precision and accuracy of sampling and analytical procedures in the modern practice of occupation hygiene. This is due to its importance in risk management in various industries, in the occupation health care and in general consumer product safety. Typical examples of current practices include external quality control by analysis of unknown control samples, certification of control samples and materials, interlaboratory comparisons, and, finally, international standardization of sampling and analytical methods. The Institute of Occupational Health Sciences (IOHS) has participated for more than twenty years in several programs of the above-mentioned approaches, and its own methods have been validated by international quality control programs

Evaluating the impacts of rice-based protection dykes on floodwater dynamics in the vietnamese mekong delta using geographical impact factor (Gif)

This study aims at evaluating the geographical influences of rice-based protection dykes on floodwater regimes along the main rivers, namely the Mekong and the Bassac, in the Vietnamese Mekong Delta (VMD). Specifically, numerous low dykes and high dykes have been constructed particularly in the upper delta’s floodplains to protect the double and triple rice cropping against the annual flooding. For the whole deltaic domain, a 1D-quasi-2D hydrodynamic model setup was used to simulate seventy-two (72) scenarios of dyke construction development in the context of low, medium, and high floods that occurred in the VMD to examine the effects of different flood magnitudes on a certain dyke construction area. Based on the model simulation results, we established an evaluation indicator, the so-called Geographical Impact Factor (GIF), to evaluate the impacts of zone-based dyke compartments on the floodwater regimes along the main rivers for different kinds of floods. Our findings revealed different rates of influences on the floodwater levels along the Mekong and Bassac Rivers under different scenarios of zone-based high-dyke developments. GIF is a useful index for scientists and decision-makers in land use planning, especially in rice intensification, in conjunction with flood management for the VMD and for similar deltas worldwide