Research into conditions of quantitivity in the determination of carboniles in complex air matrices by adsorptive solid phase microextraction

This study focuses on certain aspects of the quantitivity of adsorptive solid phase microextraction when applied in the form of on-fibre derivatisation with O-(2,3,4,5,6)-pentafluorobenzyl-hydroxylamine hydrochloride (PFBHA) for the determination of carboniles in air samples of relevance in the atmosphere. The study was performed in the high-volume outdoor atmospheric simulation chambers (EUPHORE) located in Valencia (Spain). At short sampling times, the adsorption profiles obtained when only benzaldehyde was inserted in the chamber coincided with those obtained when other carbonylic compounds were also introduced at the same concentration, and this was also the case when the concentration of all the gaseous mixture components was increased considerably from one experiment to another. In a number of experiments applying different conditions, it was proven that all the extraction profiles belonged to the same regression when the fibre responses were plotted against the concentration-time product. A number of calibrations were obtained for benzaldehyde introduced in the chamber alone and in a mixture with three other carboniles at similar concentration values. A statistical test is applied to confirm that they all belonged to the same regression since they shared homogeneous variances. After these tests, the method of SPME on-fibre derivatisation for the determination of carboniles was considered to be safely applicable to quantification. Moreover, the concentration levels at which certain unwanted effects, i.e., displacement, saturation and competition, were observed are a few orders of magnitude higher than their occurrence levels in atmospheric processes.     

Surface pressure‐area curves compression isotherm of sericin Langmuir monolayer

The Langmuir monolayer of sericin protein was studied by means of surface pressure (π)—molecular area (A) isotherms at different pH subphase. The monolayer of sericin exhibits typical phase transition phenomena at pH 2, pH 4.8, pH 7 and pH 11, respectively, including from gas state to gas‐liquid state and finally to condensed solid state. However, the monolayer of sericin on pH 11 subphase appears to be solid state. Copyright © 2007 John Wiley & Sons, Ltd.     

海气相互作用的若干时频特征

本文利用交叉谱分析方法分析了北大西洋、北太平洋以及印度洋六个海区与500百帕四个大气活动区之间的关系,揭示了它们之间的时空特点.进而分析了中低纬度海气相互作用的时频特点,并对三大洋副热带高压之间的相互关系进行了讨论,得到了一些有意叉的结果.这给利用海气关系进行长期天气过程分析提供了可靠依据。     

Small shower CORSIKA simulations

Extensive Air Showers (EAS) induced by cosmic ray particles of very low energies, owing to the significantly steep cosmic ray energy spectrum, dominate the secondary particle flux measured by single detectors and small shower arrays. Such arrays connected in extended networks can be used to determine potentially interesting spatial correlations between showers, which may shed new light on the nature of ultra high-energy cosmic rays. The quantitative interpretation of showers recorded by small local arrays requires a methodology that differs from that used by ordinary large EAS arrays operating in the "knee" region and above. We present "small EAS generator," a semi-analytical method for integrating cosmic ray spectra over energies of interest and summing over the mass spectra of primary nuclei in arbitrary detector configurations. Furthermore, we provide results on the EAS electron and muon fluxes and particle density spectra.     

Influence of vent positions on smoke clearance from a room

Results of solutions to the equations governing the clearance of smoke in laminar and in turbulent flow from a single rectilinear room are presented fof five different vent arrangements. These results show that the average smoke concentration in the room decreases in an approximately exponential manner with time at a rate that depdends much more on room geometry (vent positions in the present case) than on whether the flow is laminar or turbulent. The benefit of this observation is that, provided the clearance air jet is disrupted by impingement on a solid surface within the room, the analysis of smoke movement can for many practical purposes be limited to consideration of laminar flow only. An exceptional case is when the jet is allowed to take a straight line path between the inlet and outlet vents. Here in the absence of the large scale eddies caused by jet impingement, the smaller scale eddies of turbulent flow become relatively important as a mixing mechanism and give higher clearance rates than in laminar flow. Even so, this type of geometry is best avoided. The appearance of the jet is shown in a graphic presentation of the numerical results for laminar flow.     

Deep swirling flow down a plughole with air entrainment

Experiments have been carried out to determine the water depth required to entrain a given amount of air with a given circulating water flow discharging through a vertical pipe set in the flat bottom of a vessel. The circulation angle, , between the radial direction and the velocity vector far from discharge pipe was set at 0°, 10°, 30° or 60°.

It is shown that results are not dependent upon the diameter of the offtake pipe, if that is sufficiently small, and results are then expressed either as a dimensionless water depth vs a dimensionless ratio of the flow rates of the two phases or as a dimensionless flow rate of one phase vs the dimensionless flow rate of the other phase. An approximate theory describes trends in the data and is mostly in good quantitative agreement.

The results are used to examine the work of others on the entrainment of air or steam by water flowing along the bottom of a horizontal pipe into a small bottom offtake and the similar entrainment of water by air or steam flowing into a small top offtake. These systems occur in certain PWR loss of coolant accidents.     

生物质先进再燃脱硝特性研究

在沉降炉上研究草本类棉秆、玉米秸、麦秆和木本类梧桐木四种生物质的先进再燃脱硝特性。结果表明,20%再燃比、0.7s停留时间能保证较优的反应工况。在过量空气系数为0.7～0.9、氨氮摩尔比为1.5左右时,棉杆、玉米秸、麦秆以及梧桐木先进再燃在1273K附近取得最高脱硝效率,其值分别为89.11%、88.34%、90.33%和88.28%,比基本再燃提高25%～30%,并且生物质的再燃反应是脱硝的主体,喷氨是对再燃的完善和优化。在1173K～1473K四种生物质的先进再燃可以保持80%以上的脱硝效率。实验过程中加入100×10-6的碱金属、碱土金属添加剂可进一步改良先进再燃脱硝进程。碳酸钠、碳酸钾使脱硝效率提高3%～6%;醋酸钙在1273K～1473K将脱硝率提高4.0%～5.0%,在1073K～1273K作用规律不明显。     

Sorbent trapping solid-phase microextraction of fragrance allergens in indoor air

Exposure to fragrance substances is exponentially increasing in our daily life due to the enhanced use of scented products. Some fragrances are known to be important sensitizers, inhalation being an important exposure pathway in indoor environments. A simple and sensitive method based on solid-phase enrichment and solid-phase microextraction (SPME) followed by gas chromatography–mass spectrometry (GC–MS) has been developed for the analysis of 24 volatile fragrance allergens in indoor air. Suspected allergens present in the air (0.2 m³) were adsorbed onto a very small quantity of florisil (25 mg) and then transferred to a SPME fiber in the headspace mode (HS). To the best of our knowledge, this paper describes the first application of SPME for the determination of these compounds in air samples. The experimental parameters affecting the microextraction process have been optimized using a multifactor experimental design strategy. Accuracy, linearity, precision and detection limits (LODs) were evaluated to assess the performance of the proposed method. External calibration, using spiked sorbent standards, and not requiring the complete sampling process (only the SPME step), demonstrated to be suitable for the quantification of all suspected allergens. Recovery studies were performed at three concentration levels (0.04, 1.00 and 50 μg m⁻³), obtaining quantitative recoveries (≥85%) in most cases. LOD values at the low ng m⁻³ level were achieved for all the target compounds. The application of the method to daily home air samples demonstrated the ubiquity of this kind of fragrance ingredients in quotidian indoor environments, finding 18 of the 24 considered compounds in concentrations ranging from 0.01 to 56 μg m⁻³. Benzyl alcohol, linalool, citronellol, ionone and lilial were found in most analyzed samples.     

On-line analysis of volatile chlorinated hydrocarbons in air by gas chromatography–mass spectrometry: Improvements in preconcentration and injection steps

An analytical system composed of a cryofocusing trap injector device coupled to a gas chromatograph with mass spectrometric detection (CTI-GC–MS) specific for the on-line analysis in air of volatile chlorinated hydrocarbons (VCHCs) (dichloromethane; chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) was developed. The cryofocusing trap injector was the result of appropriate low cost modifications to an original purge-and-trap device to make it suitable for direct air analysis even in the case of only slightly contaminated air samples, such as those from remote zones. The CTI device can rapidly and easily be rearranged into the purge-and-trap allowing water and air analysis with the same apparatus. Air samples, collected in stainless steel canisters, were introduced directly into the CTI-GC–MS system to realize cryo-concentration (at −120 °C), thermal desorption (at 200 °C) and for the subsequent analysis of volatiles. The operating phases and conditions were customised and optimized. Recovery efficiency was optimized in terms of moisture removal, cold trap temperature and sampling mass flow. The injection of entrapped volatiles was realized through a direct transfer with high chromatographic reliability (capillary column–capillary column). These improvements allowed obtaining limits of detection (LODs) at least one order of magnitude lower than current LODs for the investigated substances. The method was successfully employed on real samples: air from urban and rural areas and air from remote zones such as Antarctica.     

不同温度下空气比热容比测量装置的研究

针对大学物理实验现有测量空气比热容比装置存在的不足,研制了可测量不同温度下空气的比热容比的装置,包括贮气瓶、压力传感器、温度传感器及水浴系统.该装置可使贮气瓶内空气保持在30～90℃之间的任一温度.每隔10℃测量空气的比热容比值,实验结果表明空气比热容比随温度上升而下降.