Diffraction dissociation of nuclei in 450 GeV/c proton-nucleus collisions

Diffractive dissociation of nuclei (Be, Al, W) in collisions with 450 GeV/c protons,pApX, has been measured with the HELIOS spectrometer at the CERN Super Proton synchrotron. The dependence of the single-diffraction cross-section on the nuclear massA can be parametrized as _SD mb×A ^0.35±0.02, showing the peripheral nature of the process. The differential cross-section d_SD=(3.8±0.3)mb ×A ^0.35±0.02, is exponential with the slope parameter, increasing from 6.2±0.4 (GeV/c)^–2 for beryllium to 7.9±0.5 (GeV/c)^–2 for tungsten. The slope parameter also increases with increasing massM _X of the diffractively produced state. The rapidity, multiplicity, and transverse-momentum distributions of the particles of the diffractively produced stateX show a longitudinal phase-space population and are remarkably insensitive to the nuclear mass. This, together with theA ^1/3 dependence of _SD, suggests that the dominant process of nuclear diffractive excitation is the dissociation of single nucleons.Deceased     

Determination of plasma amitriptyline by electron-capture gas chromatography after oxidation to anthraquinone.

A selective procedure is described for the determination of amitriptyline in plasma. The method involves extraction, separation of amitriptyline from its metabolites and subsequent oxidation by ceric sulphate in 5.4 M sulphuric acid. The oxidation product, anthraquinone, is determined by means of electron-capture gas chromatography. The metabolites were separated by a column chromatographic extraction technique. The choice of oxidation reagent, optimum conditions for the oxidation, and the electron-capture properties of anthraquinone are discussed. The method can be used to determine down to 2 ng of amitriptyline in a plasma sample; the relative standard deviation at the 50-ng level was 4.0% (n = 8). The levels of amitriptyline found in a series of plasma samples are compared with those obtained by gas chromatography with use of nitrogen-specific detection; the two techniques gave coincident results.     

Investigation of a cylindrical chemosorptive denuder for sampling and phase separation of toluene diisocyanate aerosols

A cylindrical chemosorptive denuder in series with a glass fibre filter has been evaluated for sampling toluene diisocyanate (TDI) aerosols. The sampler is designed for measuring personal exposure to diisocyanates. Several denuder coatings and derivatising reagents were investigated. Dimethylpolysiloxane (SE-30) and 5% phenyl dimethylpolysiloxane (SE-54) with either dibutylamine (DBA) or dipentylamine (DPeA) as derivatising reagents yielded the lowest vapour breakthrough (the amount (%) of the vapour that passes through the denuder), close to values predicted by theory. Immobilisation of the SE-30 denuder coating by in-situ cross-linking yielded comparable results. With an SE-30/DBA-coated denuder operating within an airflow range of 100–500 mL min^–1, the phase separation was shown to be consistent with theoretical predictions derived by use of the Gormley–Kennedy equation. This provides a means of calculating the vapour breakthrough and correcting experimentally obtained values with regard to vapour–particulate phase distribution, suggesting that the denuder can provide accurate phase-distribution measurements. The SE-30/DBA denuder can be used over a concentration range spanning nearly six orders of magnitude. Its capacity is sufficient to perform 15-min exposure measurements of a TDI aerosol with air concentrations as high as 1,700 g m^–3, 40 times higher than the Swedish occupational exposure limit (OEL). At the other end of the range, the estimated limit of detection (LOD) was less than 2 ng m^–3 for both the vapour and the aerosol phases when LC–ESI–MS–MS was used for chemical analysis.Electronic Supplementary Material Supplementary material for this article is available at     

Determination of fatty acids in atmospheric samples via GC/MS

Summary Atmospheric precipitation and aerosol samples are characterized by a complex mixture of several organic compounds. A simple method for the simultaneous determination of the main compound classes by GC/MS is presented. In detail, seasonal variations of C₈–C₃₂ fatty acids in precipitation in a semirural area have been studied. Total fatty acids concentrations of 7–53 g/l were detected. Summer rain is characterized by high amounts of fatty acids >C₂₀ and lower amounts of C₁₁–C₂₀ species. Two effects may be responsible: larger emission rates of fatty acids during vegetation periods and an increased influence of vapour phase due to higher temperatures during summer. CPI values showed no general trend; lower CPI values for winter rain could not be observed. This would be expected if anthropogenic sources play an important role. Monounsaturated fatty acids (C_16:1, C_18:1) were more abundant during winter than in summer. High concentrations of polyunsaturated fatty acids (C_18:x) could be detected during summer. High relative concentrations of the potential oxidation products of the unsaturated species, nonanedioic acid and w-oxononanoic acid, are associated with relatively low concentrations of their precursors.     

16, 18O induced transfer reactions on122, 120Sn

The reactions¹²⁰Sn+72 MeV¹⁸O and¹²²Sn+74 MeV¹⁶O were investigated with time of-flightE-E-telescopes. Data are presented for all quasi-elastic reaction channels. The two neutron stripping and pickup reactions (¹⁸O,¹⁶O), (¹⁸O,²⁰O) and (¹⁶O,¹⁸O) are analyzed in detail. It is shown that these heavy ion induced two neutron transfer reactions proceed with essentially the same type of selectivity as the corresponding light ion induced reactions. The differential cross sections for transfer reactions leaving the^{120, 122}Sn nuclei in their 2⁺ first excited states are shown to be influenced by interference effects due to additional inelastic excitations.     

Inner-shell ionization ofZ=25–32 elements by 5-48 MeV32S ions

TheK-shell ionization cross sections of Mn, Ni, Cu, Zn and Ge under³²S bombardment have been measured in the energy range from 5 to 48 MeV. The cross sections are compared with available theories based on a direct Coulomb ionization mechanism and with the predictions of theK-vacancy sharing process. This last process can reasonably account for the measured cross sections at high bombarding energies. The energy shifts of theK - andK -lines and theK /K -intensity ratios have also been measured. This information is used to deduce the defect configuration of the atoms. The mechanisms responsible for the multiple vacancy production are discussed.     

Development of a nanostructured filter for pyrolysis wax purification:Effects of particulate filter aids

Wax obtained from the pyrolysis of polyethylene waste can contain inorganic contaminants and must be purified before application.We evaluated different filter aids(perlite,sand,and rice husk ash)for the filtration of a crude wax and a pyrolysis wax through a filter medium that was coated with nylon 6 nanofibers to improve filtration efficiency.We first examined the performance of the filter aids in improving crude wax filtration,with the filtration time,temperature,and pressure held constant at 1 h,170℃,and 2.5 bar,respectively.Oily wax was then produced by pyrolysis of high-density polyethylene(HDPE)waste in the temperature range 425-475℃.The best filter aid was perlite,which had a filtrate production rate of 5.47×10^-5m³/h.The highest oily wax yield(87.8%)was achieved at a pyrolysis temperature of 425℃.The assembly comprising the filter medium coated with nylon 6 nanofibers plus perlite as a filter aid was most suitable for removing impurities from the oily wax generated by the HDPE pyrolysis as it achieved a purification efficiency of 99.9%.     

Selective CO2 reduction into formate using Ln-Ta oxynitrides combined with a binuclear Ru(Ⅱ)complex under visible light

Hybrid materials constructed from a visible-light-absorbing semiconductor and a functional metal complex have attracted attention as efficient photocatalysts for CO₂ reduction with high selectivity to a desired product.In this work,defect fluorite-type Ln-Ta oxynitrides LnTaO_xN_y(Ln=Nd,Sm,Gd,Tb,Dy and Ho)were examined as the semiconductor component in a hybrid photocatalyst system combined with known Ag nanoparticle promoter and binuclear ruthenium(Ⅱ)complex(RuRu’).Among the LnTaO_xN_y examined,TbTaO_xN_y gave the highest performance for CO₂ reduction under visible light(k>400 nm),with a Ru Ru0-based turnover number of 18 and high selectivity to formate(>99%).Physicochemical analyses indicated that high crystallinity and more negative conduction band potential of Ln Ta O_xN_ywith the absence of Ln-4 f states in the band gap structure contributed to higher activity of the hybrid photocatalyst.     

Preparation of CdO nanoparticles by mechanochemical reaction

CdO nanoparticles of 43 nm in crystal size were successfully synthesized by the mechanochemical reaction (CdCl₂ + Na₂CO₃) with NaCl as a diluent and subsequent thermal treatment at 700°C for 2 h. The samples were characterized by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Effect of calcination temperature on the crystal size of CdO nanoparticles was primarily investigated. The apparent activation energy of CdO nanoparticle formation during thermal treatment was calculated to be 12.2 kJ/mol.     

Spectral Properties and Solubilization Location of 2'-Ethylhexyl 4-(N,N-Dimethylamino)benzoate in Micelles

在阳离子、非离子和阴离子表面活性剂胶束溶液中,研究了4-(N,N-二甲氨基)苯甲酸2'-乙基己基酯(EHDMAB)的双重荧光和紫外吸收．当EHDMAB增溶在不同的胶束溶液中,紫外吸收增强,在离子型胶束溶液中,可观察到具有较长波长的EHDMAB分子内扭转电荷转移(TICT)荧光,相反,在非离子型胶束溶液中,可观察到具有较短波长TICT荧光,特别是位于阳离子胶束Stern层中的吡啶阳离子可强烈猝灭EHDMAB分子的双重荧光,所吸收的紫外辐射主要通过TICT荧光和非辐射去活化衰减．按照EHDMAB分子TICT荧光在有机溶剂中的极性依赖性,EHDMAB分子的4-(N,N-二甲氨基)在离子型胶束和非离子型胶束中处于不同的极性环境;根据EHDMAB和表面活性剂分子的结构和大小分析,EHDMAB分子的4-(N,N-二甲氨基)应朝向胶束的极性头基团,而2'-乙基己基链则朝向疏水性的胶束内核．动态荧光猝灭测量为EHDMAB分子在不同胶束中的位置进一步提供了佐证．