Organic aerosols in the air of Milan,Italy. The IIA‐CNR measurement campaign of 2000–2001

Inhalable aerosols collected in downtown Milan during a whole‐year field campaign (from November 2000 to October 2001) were investigated to determine amounts of n‐alkanes, polynuclear aromatic hydrocarbons (PAH), including benzo[a]pyrene (BaP), nitrated PAH (NPAH), and monocarboxylic n‐alkanoic acids. Combustion processes including vehicle emission were confirmed as the most important sources affecting air quality, whereas release of organic material from biota contributed a few percent. The occurrence of in‐situ reactions in the atmosphere promoted by oxidants modified, to some extent, the composition of both PAH and NPAH fractions, by reducing the amount of BaP present in the aerosols and increasing that of NPAH.     

离子液体降低FCC汽油烯烃体积分数的研究

向FCC汽油中分别加入两种与FCC汽油不互溶的Lewis超强酸性离子液体\[Bmim\]Cl-AlCl3 和 \[R4N\]Cl-AlCl3形成液-液两相催化降烯烃体系。结果表明：在汽油辛烷值基本保持不变的基础上,FCC汽油的烯烃体积分数分别下降14.7%和13.1%, 均达到我国新配方汽油规定的烯烃体积分数v<35%的新标准。对离子液体降低FCC汽油的机理及影响因素进行了详细研究。结果表明,正是由于具备Lewis超强酸性的离子液体催化的烯烃与烷烃的烷基化、烯烃与芳烃的烷基化以及烯烃的二聚反应使得FCC汽油中烯烃体积分数显著下降。     

Density and phase diagram of the magnesium–lead system in the region of Mg2Pb intermetallic compound

The phase diagram of magnesium–lead system has been investigated by a new method for phase analysis on the basis of a strong penetrating radiation. The measurements have shown that the standard phase diagram of this system contains inaccuracy in the region of the Mg₂Pb intermetallic compound. New data on the temperature dependences of the solid and the melt densities have been obtained. The density change during the phase transitions has been directly measured.     

F改性Hβ对Mo-Ni/F-Hβ催化剂的FCC汽油硫转移反应催化性能的影响

通过添加不同含量的F对Hβ分子筛进行改性,制备Mo-Ni/F-Hβ催化剂,采用N₂吸附-脱附、NH₃-TPD、XRD、Py-FTIR和SEM等方法对该催化剂进行了表征,研究了F改性对该Mo-Ni/F-Hβ催化剂在FCC汽油中硫醇醚化和噻吩烷基化等硫转移反应中催化性能的影响。结果表明,以0.5%含量F修饰的β分子筛制备的催化剂对硫醚化反应和噻吩烷基化反应具有明显的促进作用,并能提高对二烯烃选择性加氢的选择性。F的引入可增强Hβ分子筛的中强酸量,降低强酸量,并提高了L/B酸中心比例,这些变化对催化性能改善起到重要作用。     

Evaluation of the factors affecting extraction of organic compounds based on the acid-induced phase cloud point approach

On the basis of a better analytical exploitation of acid-induced cloud point approach, a systematic study on the phase behaviour of acid aqueous solutions of anionic surfactants and factors affecting anionic surfactant-mediated extractions was performed. The anionic surfactants investigated were alkylsulphonates (ASS) with alkylchain lengths comprised between 8 and 16 carbon atoms. The critical hydrochloric acid concentration (minimal acid concentration required to separation in two liquid phases) was found to increase as alkylchain length of the anionic surfactant increased from 10 to 14. Non-acid-induced liquid-liquid phase separation was observed for sodium octanesulphonate (SOS) or sodium hexadecyl sulphonate (SHS) in the hydrochloric concentration range 0-10 M. Acid aqueous solutions of sodium decylsulphonate (SDeS) and sodium dodecylsulphonate (SDoS) separated into two liquid phases at temperatures ranging between 10 and 80 °C, while temperatures >35 °C were required for sodium tetradecylsulphonate. The influence on extraction efficiency and concentrating ability of experimental variables such as hydrophobicity and concentration of surfactant, nature and concentration of analyte, hydrochloric acid concentration, time and temperature of extraction and time of equilibration and centrifugation was examined. Advantages provided by anionic surfactant-mediated extractions over the use of non-ionic surfactants (cloud point extractions) are discussed.     

雾过程对大气气溶胶PM10中多环芳烃粒径分布的影响

在雾天气高发期间采集大气气溶胶PM10分级样品,测定了这些样品中的16种优控PAHs.结果表明：雾区近地层大气中PM2.1和PM9.0的平均质量浓度明显增加,雾过程改变了PM2.1的昼、夜浓度变化特征;雾前、雾中与雾后大气PM10中16种优控PAHs主要分布在比表面积大的细粒子上,平均有83.04%分布在Dp <2.1μm的范围,雾中1.1~2.1μm粒子的∑16PAHs浓度明显增加,Dp <0.65μm粒子的∑16PAHs浓度略有降低,说明雾过程对细粒子中∑16PAHs的浓度分布产生明显影响;雾前、雾中与雾后白天时间段,PM10分级粒子的∑16PAHs积聚模态分布出现较大差异,雾中积聚模态峰位置较雾前与雾后向较大粒径偏移;一次连续雾过程中,白天的∑16PAHs积聚模态峰位置随着雾的持续向大粒径方向偏移并停留在1.1~2.1μm;夜间的∑16PAHs积聚模态峰位置没有变化,均在1.1~2.1μm,说明PM10∑16PAHs的粒径分布受雾过程持续时间影响较大.     

The effect of NaCl and Na2SO4 concentration in aqueous phase on the phase inversion temperature O/W nanoemulsions

The effect of NaCl and Na₂SO₄ concentrations in aqueous phase on the phase inversion temperature (PIT) in nanoemulsions of water/Brij30/n-hexadecane system has been studied separately, and then compared. The variation of conductivity with temperature was measured by Cyber Scan PC510 conductivity meter for emulsions with 20 wt% hexadecane and 8 wt% Brij30 concentration and different concentrations of NaCl and Na₂SO₄ in aqueous phase. The results showed that with increasing concentrations of NaCl and Na₂SO₄ in aqueous phase, the PIT of nanoemulsions decreases. The effect of the elevation of concentration on the decrease of PIT was more for Na₂SO₄ in aqueous phase than NaCl with equal concentrations.     

Centrifugeless ultrasound‐assisted emulsification microextraction based on salting‐out phenomenon followed by high‐performance liquid chromatography for the simple determination of phthalate esters in aqueous samples

A fast, sensitive, and centrifugeless ultrasound‐assisted emulsification microextraction followed by a high‐performance liquid chromatography method is developed for the determination of some phthalate esters in aqueous samples. In this method, a simple approach is followed to eliminate the centrifugation step in dispersive liquid–liquid microextraction using an organic solvent whose melting point is near the ambient temperature, consumption of the extracting solvent is efficiently reduced, and the overall extraction time was found to be only 7 min. The variables affecting the method are optimized. Under the optimal experimental conditions (75 μL of 1‐undecanol, a flow rate of 2.0 mL/min, and an ultrasound irradiation of 1 min), the proposed method exhibits good preconcentration factors (52–97), low limits of detection (1.0–5.0 ng/mL), and linearities in the range of 5–1500 ng/mL (r ² ≥ 0.995). Finally, the method is successfully applied to the analysis of phthalate esters in the drinking and river water samples. To study the probable release of the phthalate esters from a polyethylene container into boiling water, the boiling water exposed to the polyethylene container was analyzed by the proposed method.     

Effect of molecular weight distribution on the liquid-liquid phase separation behavior of polydispersed polyethylene solutions at high temperatures

The phase behaviors of the hexane + polydispersed polyethylene (PE) systems were measured to clarify the effect of the molecular weight distribution (MWD) of PE on liquid-liquid (LL) phase boundaries. The weight fraction for the PE portion of a maximum LL phase separation pressure in the LL phase boundary decreased as the polydispersity of PE increased. Moreover, depression of the phase separation pressure from the maximum phase separation pressure on the higher PE weight fraction side was more drastic as the polydispersity of the PE increased. The LL phase boundaries were correlated using the Sanchez-Lacombe equation of state (S-L EOS). For the correlations, the polydispersed PEs were regarded as mixtures of 16 types of monodispersed PEs with different molecular weights, and the characteristic parameters of the S-L EOS, P*, ρ* and T*, were assigned the same values for all monodispersed PEs even though the molecular weights differed. However, the interaction parameters of the hexane-PE pairs depended on the molecular weight of the PE and the temperature. The correlated results capably reproduced the effect of the MWD of the PE on the LL phase boundaries for the hexane + polydispersed PE systems.     

The effect of disorder in Ba2YTaO6 on the tetragonal to cubic phase transition

Synchrotron X-ray diffraction and Raman spectroscopy have been used to study the structure of the complex perovskite Ba₂YTaO₆, at temperatures down to 100 K. Where the Ta and Y cations exhibit long-range rock-salt like ordering, Ba₂YTaO₆ displays a continuous phase transition from a high temperature cubic structure, described in space group Fm3?m, to a tetragonal, I4/m, structure near 260 K. This transition is inhibited if extensive disorder and/or vacancies are/is present in the sample.     

Effect of anionic structure on the phase formation and hydrophobicity of amino acid ionic liquids aqueous two-phase systems

Compared with the conventional ionic liquids, amino acid ionic liquids are more biodegradable and biocompatible, and can enhance stability of biomaterials. In this work, amino acid ionic liquids 1-butyl-3-methylimidazolium L-serine ([C(4)mim][Ser]), 1-butyl-3-methylimidazolium glycine ([C(4)mim][Gly]), 1-butyl-3-methylimidazolium L-alanine ([C(4)mim][Ala]) and 1-butyl-3-methylimidazolium L-leucine ([C(4)mim][Leu]) have been synthesized. These ionic liquids are found to form aqueous two-phase systems (ATPSs) by the salted-out of K(3)PO(4) in aqueous solutions. Phase diagram of the ATPSs and the Gibbs energies of transfer of methylene group from the bottom salt-rich phase to the top ionic liquid-rich phase have been determined at 298.15K and pH 14, and the effect of anionic structure of the ionic liquids on phase formation of the ATPSs and the relative hydrophobicity between the top and the bottom phases are then examined. In order to understand the effect of relative hydrophobicity of the phases in equilibrium in the ATPSs on the extraction/separation capability of biomolecules, the partition coefficients of cytochrome-c (as a model biomolecule) in the ATPSs are measured by spectrophotometry. It is suggested that hydrophobic interactions are mainly responsible for the higher partition coefficients of cytochrome-c in aqueous two-phase systems at pH 14, and the extraction and separation capacity of biomolecules can be improved by the modulation of the relative hydrophobicity of the phases and/or the pH of the system.     

镇海城关儿童血铅水平及相关因素调查分析

为了解镇海城关 1～ 6岁儿童血铅水平现状及相关因素 ,进一步进行儿童铅中毒的防治提供依据 ,对城关 1～ 6岁、在区妇幼保健院体检 1 5 71名健康儿童进行了血铅测定并对其家庭生活环境及个人情况等相关因素进行了问卷调查。结果表明 ,本次调查 1 5 71名儿童中 ,血铅平均数为2 5 8μg/gHb ,其中高于 3μg/gHb儿童 5 31人 ,占 33 8% ,而且年龄越小 ,血铅超标率越高 ,P<0 0 1。儿童血铅并与居住地与汽车马路的间距、生活环境中油漆接触均有密切关系 ,P <0 0 1。血铅增高 ,儿童多动症、贫血发生率明显上升 ,P <0 0 1。可见镇海城关地区儿童血铅水平及儿童流行率已较高 ,应引起高度重视     

Impact of ageing on the distribution of platinum group elements and catalyst poisoning elements in automobile catalysts

The distribution of platinum group elements (PGEs) and catalyst poisoning elements (Pb, Zn, P and S) on the surface of gasoline and diesel automobile catalysts was investigated within this study. Laser ablation–inductively coupled plasma mass spectrometry (LA–ICPMS) provides both the sensitivity and the spatial resolution required for the surface analysis of sectioned automobile catalysts, and scanning along channels reveals the distribution of longitudinal changes in PGE and catalyst poisoning elements. Changes in catalyst surface features were studied for fresh catalysts and after ageing of the catalyst up to 80 000 km for both types of catalysts studied. The PGEs in the gasoline catalyst were found to decrease at the front of the catalyst after ageing, whereas the diesel catalyst presented a more constant loss along the catalyst. The fraction of poisoning elements (Pb, P and Zn for the gasoline catalyst and P and Zn for the diesel catalyst) retained by the catalyst is distributed non‐uniformly over the length of the catalyst. This could indicate different ageing mechanisms for gasoline and diesel catalysts. Copyright © 2003 John Wiley & Sons, Ltd.     

Impact of column and stationary phase properties on the productivity in chiral preparative LC

By generating 1500 random chiral separation systems, assuming two‐site Langmuir interactions, we investigated numerically how the maximal productivity (P_R,max) was affected by changes in stationary phase adsorption properties. The relative change in P_R,max, when one adsorption property changed 10%, was determined for each system and for each studied parameter the corresponding productivity change distribution of the systems was analyzed. We could conclude that there is no reason to have columns with more than 500 theoretical plates and larger selectivity than 3. More specifically, we found that changes in selectivity have a major impact on P_R,max if it is below ∼2 and, interestingly, increasing selectivity when it is above ∼3 decreases P_R,max. Increase in relative saturation capacity will have a major impact on P_R,max if it is below ∼40%, but only modest above this percent. Increasing total monolayer saturation capacity, or decreasing the first eluting enantiomer's retention factor, will have a modest effect on P_R,max and increased efficiency will have almost no effect at all on P_R,max unless it is below ∼500 theoretical plates. Finally, we showed that chiral columns with superior analytic performance might have inferior preparative performance, or vice versa. It is, therefore, not possible to assess columns based on their analytical performance alone.     

Effect of strontium deficiency on the critical behavior at paramagnetic to ferromagnetic phase transition in La0.57Nd0.1Sr0.33MnO3 manganite oxide

The samples of manganese perovskite La_0.57Nd_0.1Sr_0.33−x_xMnO₃ (0.00 ≤ x ≤ 0.05) ( is the strontium deficiency) are prepared by solid-state methods, and all of them have a rhombohedral perovskite structure, revealed by X-ray diffraction. The critical properties of the samples around the paramagnetic–ferromagnetic phase transition were investigated through various techniques such as modified Arrott plot (MAP), Kouvel–Fisher (KF) method and critical isotherm (CI) analysis based on the data of static magnetic measurements recorded around the Curie temperature T_C. The experimental results have revealed that the samples exhibited the second-order magnetic phase transition and the critical exponents of β and γ for La_0.57Nd_0.1Sr_0.33MnO₃ are close to those found out by the 3D-Heisenberg model. Furthermore, the estimated critical exponents of La_0.57Nd_0.1Sr_0.33−x_xMnO₃ (x = 0.025 and 0.05) are consistent with the prediction of the 3D-Ising model. We deduced, following the Harris criterion, that the disorder in our case is relevant which can be the cause of the change in the universality class and we noted that the critical exponents β are almost similar to the value of the mean-field theory which can be explained by the existence of a long-range dipole–dipole interaction.     

The effect of glass transition on phase separation in binary off-critical blends: different coarsening regimes near the nonequilibrium percolation threshold

The nonequilibrium percolation threshold was shown to take an intermediate position between binodal and mean-field spinodal. Below the nonequilibrium percolation threshold, a bicontinuous phase structure was produced. This percolation structure, depending on supersaturation, breaks down to ramified clusters slowly assuming a spherical droplet form or contracts to the center of the sample. In the latter case, at late stages, secondary phase separation is observed. Accepted: 21 September 1998     

Comparison of direct-total-reflection X-ray fluorescence,sweeping-total-reflection X-ray fluorescence and vapor phase decomposition-total-reflection X-ray fluorescence applied to the characterization of metallic contamination on semiconductor wafers

The issues related to the matching between the 3 modes of Total-reflection X-Ray Fluorescence available on the latest generation of commercial equipment: Direct-Total-reflection X-Ray Fluorescence, Sweeping-Total-reflection X-Ray Fluorescence and Vapor Phase Decomposition-Total-reflection X-Ray Fluorescence, are discussed for quantitative analysis of metallic contamination on Si wafers. Direct-Total-reflection X-Ray Fluorescence and Sweeping-Total-reflection X-Ray Fluorescence agrees very well (+/− 20% for light elements, transition metals and heavy metals), but due to a poor surface coverage with Direct-Total-reflection X-Ray Fluorescence, the matching is correct on a whole wafer only for uniform contaminations. Vapor Phase Decomposition-Total-reflection X-Ray Fluorescence might agree with other Total-reflection X-Ray Fluorescence modes only if the collection of contaminants following the oxide decomposition step is 100% completed. This is not achieved for 2 situations: noble metals which plate on bare Si, and solid particles partially digested during the Vapor Phase Decomposition and collection protocol. Furthermore, even if the collection of contaminants is well completed, quantification after Vapor Phase Decomposition depends on the shape of the dried residues and the Total-reflection X-Ray Fluorescence incident angle. With the incident angle selected to maximize the signal to noise ratio for ultra trace applications, i.e. about 0.5 times the Si critical angle, an increase of the quantification by a factor up to 10 is often seen after Vapor Phase Decomposition because of particle-like shape of the metals against film-like shape for the initial distribution. Taking into account advantages and drawbacks of each Total-reflection X-Ray Fluorescence mode, a proposal for the use of Total-reflection X-Ray Fluorescence in advanced Integrated Circuit manufacturing is given and illustrated by practical results from a R&D pilot line and a mass production plant.     

New oil‐in‐salt liquid‐phase microextraction on permutite for the extraction and concentration of alkaloids in Coptis chinensis

A novel oil‐in‐salt liquid‐phase microextraction was developed and introduced for the extraction and concentration of the trace levels of active alkaloids in Coptis chinensis prior to being analyzed by high‐performance liquid chromatography with ultraviolet detection. Also, the oil‐in‐salt extraction mechanism was analyzed, the enrichment factor and extraction recovery were redefined, and the proposed method was compared with other methods. In the approach, the mixed solvent of pentanol/octanol (6:4, v/v) and NaCl (20% w/v) are immobilized on the permutite surface in turn to form oil‐in‐salt double membranes, through which the target analytes can be molecularized though salting‐out effect and be extracted by organic solvent. The main parameters affecting the approach were investigated and optimized. Under the optimized conditions, the enrichment factors of the analytes were 30–117, the linear ranges were 0.002–2 μg/mL for jatrorrhizine, coptisine, and palmatine, and 0.001–3 μg/mL for berberine (r ² ≥ 0.9923). The limits of detection were less than 1 ng/mL. Satisfactory recoveries (84.3%–120.3%) and precision (0.9%–7.5%) were also obtained. These results confirm that the approach is a simple and reliable sample pretreatment procedure and allows for the quantification of active alkaloids in C. chinensis at actual concentration levels.