界面酸碱配位作用对粘合性能影响的研究

通过测定参照液在固体表面的接触角并计算接触体系的粘附功及其酸碱作用成份,研究了带碱性基团的丙烯酰胺——天然橡胶接枝聚合物和带酸性基团的丙烯酸——天然橡胶接枝聚合物表面的酸碱配位作用及其对粘合性能的贡献.     

Simultaneous quantification of free fatty acids,free sterols,squalene, and acylglycerol molecular species in palm oil by high-temperature gas chromatography-flame ionization detection

This paper discusses a rapid GC-FID technique for the simultaneous quantitative analysis of FFA, MAG, DAG, TAG, sterols, and squalene in vegetable oils, with special reference to palm oil. The FFA content determined had a lower SE compared with a conventional titrimetric method. Squalene and individual sterols, consisting of β-sitosterol, stigmasterol, campesterol, and cholesterol, were accurately quantified without any losses. This was achieved through elimination of tedious conventional sample pretreatments, such as saponification and preparative TLC. With this technique, the separation of individual MAG, consisting of 16∶0, 18∶0, and 18∶1 FA, and the DAG species, consisting of the 1,2(2,3)- and 1,3-positions, was sufficient to enable their quantification. This technique enabled the TAG to be determined according to their carbon numbers in the range of C₄₄ to C₅₆. Comparisons were made with conventional methods, and the results were in good agreement with those reported in the literature.     

Mercury distribution and speciation in Lake Balaton, Hungary

The distribution and speciation of mercury in air, rain, lake water, sediment, and zooplankton in Lake Balaton (Hungary) were investigated between 1999 and 2002. In air, total gaseous mercury (TGM) ranged from 0.4 to 5.9 ng m(-3) and particulate phase mercury (PPM) from 0.01 to 0.39 ng m(-3). Higher concentrations of both TGM and PPM occurred during daytime. Higher concentrations of PPM occurred in winter. In rain and snow, total mercury ranged from 10.8 to 36.7 ng L(-1) in summer but levels up to 191 ng L(-1) in winter. Monomethylmercury (MMHg) concentrations ranged from 0.09 to 1.26 ng L(-1) and showed no seasonal variations. Total Hg in the unfiltered lake water varied spatially, with concentrations ranging from 1.4 to 6.5 ng L(-1). Approximately 70% of the total Hg is dissolved. MMHg levels ranged from 0.08 to 0.44 ng L(-1) as total and from 0.05 to 0.37 ng L(-1) in the dissolved form. Lower Hg concentrations in the water column occurred in winter. In suspended particulate matter and in sediment, total mercury ranged from 9 to 160 ng g(-1) dw, and MMHg ranged from 0.07 to 0.84 ng g(-1) dw. In zooplankton, an average mercury level of 31.0+/-6.8 ng g(-1) dw occurred, with MMHg accounting for approximately 17%. In sediments, suspended-matter- and zooplankton-high Hg and MMHg levels occurred at the mouth of the River Zala, but, in the lake, higher concentrations occurred on the Northern side, and an increasing trend from north-west to north-east was observed. In general, regarding Hg, Lake Balaton can be considered as a relatively uncontaminated site. The high-pH and well-oxygenated water as well as the low organic matter content of the sediment does not favour the methylation of Hg. In addition, bioconcentration and bioaccumulation factors are relatively low compared to other aquatic systems.     

Using structural equation model to explore occupational lead exposure pathways

The aim of the present study was to demonstrate the use of a structural equation model to explore the complicated lead exposure pathways in a lead battery plant. A total of 96 out of 113 assembly workers were recruited in this study. Lead measurements included blood lead, respirable airborne lead, and body surface lead loadings. Latent variables of inadvertent contact of lead on fingers and ingested lead had indirect and direct effects on the blood lead levels, respectively, and so did the variables of respirable airborne lead, smoking, and the working-place clothes being washed. A model chi(22)2 value of 31.1 (P=0.094) for a goodness of fit test indicates that the derived structural equation model appropriately accounted for the variation of blood lead levels. It is concluded that lead loadings on fingers and lips had significant effects on occupational lead uptake, and, after-work hours and break times at work were the critical time periods for inadvertent lead exposure.     

Elasto-optics in double-coated optical fibers induced by axial strain and hydrostatic pressure

Stresses, microbending loss, and refractive-index changes induced simultaneously by axial strain and hydrostatic pressure in double-coated optical fibers are analyzed. The lateral pressure and normal stresses in the optical fiber, primary coating, and secondary coating are derived. Also presented are the microbending loss and refractive-index changes in the glass fiber. The normal stresses are affected by axial strain, hydrostatic pressure, material properties, and thickness of the primary and secondary coatings. It is found that microbending loss decreases with increasing thickness, the Young's modulus, and the Poisson's ratio of the secondary coating but increases with the increasing Young's modulus and Poisson's ratio of the primary coating. Similarly, changes in refractive index in the glass fiber decrease with the increasing Young's modulus and Poisson's ratio of the secondary coating but increase with the increasing Young's modulus and Poisson's ratio of the primary coating. Therefore, to minimize microbending loss induced simultaneously by axial strain and hydrostatic pressure in the glass fiber, the polymeric coatings should be suitably selected. An optimal design procedure is also indicated.     

Inherent and apparent scattering properties of coated or uncoated spheres embedded in an absorbing host medium

The conventional Lorenz-Mie formalism is extended to the case for a coated sphere embedded in an absorbing medium. The apparent and inherent scattering cross sections of a particle, derived from the far field and near field, respectively, are different if the host medium is absorptive. The effect of absorption within the host medium on the phase-matrix elements associated with polarization depends on the dielectric properties of the scattering particle. For the specific cases of a soot particle coated with a water layer and an ice sphere containing an air bubble, the phase-matrix elements -P12/P11 and P33/P11 are unique if the shell is thin. The radiative transfer equation for a multidisperse particle system embedded within an absorbing medium is discussed. Conventional multiple-scattering computational algorithms can be applied if scaled apparent single-scattering properties are applied.     

Retrieval of atmospheric-temperature and water-vapor profiles by use of combined satellite and ground-based infrared spectral-radiance measurements

A nonlinear sounding retrieval algorithm is used to produce vertical-temperature and water-vapor profiles from coincident observations taken by the airborne High-resolution Interferometer Sounder (HIS) and the ground-based Atmospheric Emitted Radiance Interferometer (AERI) during the SUbsonic Contrails and Clouds Effects Special Study (SUCCESS). Also, clear sky Geostationary Operational Environmental Satellite (GOES) and AERI radiance measurements, achieved on a daily real-time basis at the Department of Energy's Oklahoma CART (Cloud and Radiation Testbed) site, are used to demonstrate the current profiling capability by use of simultaneous geostationary satellite and ground-based remote sensing observations under clear-sky conditions. The discrepancy principle, a method to find the proper smoothing parameters from the minimum value between the normalized spectral residual norm and the a priori upper bound, is used to demonstrate the feasibility and effectiveness of on-line simultaneous tuning of the multiple weighting and smoothing parameters from the combined satellite/airborne and ground-based measurements for the temperature and water-vapor retrieval in this nonlinear-retrieval process. An objective method to determine the degrees of freedom (d.f.) of the observation signal is derived. The d.f. of the radiance signal for the combined GOES and AERI measurements is larger than that for either instrument alone; while the d.f. of the observation signal for the combined GOES and AERI measurements is larger than that for either instrument alone and of the combined GOES and AERI measurements. The use of simultaneous clear-sky AERI and GOES data now provides improved vertical temperature and moisture soundings on an hourly basis for use in the Atmospheric Radiation Measurement program [J. Appl. Meteorol. 37, 875 (1998)].     

Diffusion-related implications for langasite resonator operation

Oxygen and gallium diffusivities in langasite were experimentally determined by analysis of diffusion profiles of 18O and 71Ga tracers by SIMS analysis as functions of temperature and doping. Strontium-enhanced diffusivities and activation energies of approximately 1.2+/-0.2 eV confirm the predominant role of oxygen vacancies in controlling the electrical conductivity of langasite at elevated temperature and oxygen partial pressure. The potential impact of high levels of porosity and the use of an oxygen primary ion beam on the accuracy of some of the data is discussed. The gallium diffusivity, with activation energy of 3.13 eV, was found to be more than two orders of magnitude lower than that of oxygen. Surface exchange measurements enabled estimation of gallium loss at elevated temperatures and oxygen partial pressure; the level is not believed to be of major concern for resonator performance.