Solid-phase extraction for simultaneous separation and preconcentration of Fe(III) and Zn(II) traces using three chelatants and Ramelak bark-derived activated carbon as a new bio-sorbent

This article introduces a comparative study for the simultaneous separation and preconcentration of Fe(III) and Zn(II) traces in various water samples using three well-known ligands as chelating agents and activated carbon (AC) derived from Ramelak bark as a new bio-sorbent prior to the determination by ?ame atomic absorption spectrometry. The chelating agents were 4,4’-[(4-Cyano-phenyl)methylene]bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) (CMBM), diethyldithiocarbamate (DDTC) and ammonium pyrrolidine dithiocarbamate (APDC). CMBM was synthesized by a procedure reported in the literature. The newly prepared AC was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared (FTIR) Spectrometry. The analytical parameters affecting the separation efficiency of the analytes including pH, shaking time, chelating agent volume (concentration), sorbent mass, sample ?ow rate and elution conditions were investigated and discussed. Common coexisting ions did not seriously interfere with the separation, showing the good selectivity of the proposed method. The calibration graph was linear in the range of 0.35–70, 0.50–80, 0.9–100, 0.55–75, 0.75–90 and 1.0–120 ng mL^?1 for Fe-CMBM, Fe-DDTC, Fe-APDC, Zn-CMBM, Zn-DDTC and Zn-APDC, respectively. Under optimized conditions, the limits of detection were 0.11, 0.13, 0.27, 0.16, 0.22 and 0.30 ng mL^?1 for Fe-CMBM, Fe-DDTC, Fe-APDC, Zn-CMBM, Zn-DDTC and Zn-APDC, respectively. The proposed method has been applied to the determination of Fe(III) and Zn(II) in different water samples with satisfactory recovery percentages. The developed method, validated with standard reference materials, was used successfully in determining the concentrations of metal ions in water samples.     

Mass Transport in Shallow Turbulent Wake Flow by Planar Concentration Analysis Technique

A planar concentration analysis (PCA) system is used for observing the transport and mixing of a tracer mass in a shallow turbulent free-surface wake flow of a large cylindrical obstacle. The nonintrusive, fieldwise PCA measuring technique is applied to evaluate depth-averaged mass concentrations by making use of light attenuation due to absorption and scattering processes related to a dissolved tracer mass. The scalar fields are decomposed into a low-frequency quasiperiodic part, the coherent flow, and a randomly fluctuating part. From accompanying near-surface velocity measurements, large-scale coherent structures are identified and related to the coherent mass fields. This allows one to assess the role of the large-scale vortices for advection and diffusion in shallow wake flows. The time–mean wake flow displays a self-similar spanwise distribution both for mass and velocity. The longitudinal development of shallow wakes initially shows the growth of unbounded wakes; in the wake far field an attenuated behavior applies.     

Arsenic and phosphorus codiffusion during silicon microelectronic processes

Arsenic (As) and phosphorus (P) implantations are concurrently used to create the n-zones of recent microelectronic device pn-junctions. We studied the As-P codiffusion effect on the junction depths during the dopant activation process. As diffusion is accelerated during codiffusion. The acceleration magnitude depends on As concentration and varies during annealing time. Contrasting with usual transient-enhanced-diffusion phenomena, a time delay can be observed before As diffusion acceleration occurs. P diffusion shows no specific modification due to codiffusion. Its diffusion behavior can be understood considering the usual Fermi level and electrical effects linked to the time evolution of the two dopant distributions. The behavior of As during codiffusion is discussed using finite element simulations.     

硝酸一次消解-原子荧光法同时测定蔬菜中的砷和汞

建立了电热板加热、硝酸一次消解,原子荧光法同时测定蔬菜中痕量砷、汞的方法。方法检出限低,砷、汞检出限分别为0.032、0.005μg·L-1,精密度和准确度高,样品砷和汞加标回收率分别为90%~110%和86%~103%。方法快捷、简单、准确和灵敏,适合基层单位在日常工作中检测大量蔬菜样品中的砷汞。     

Mass balance soil ingestion estimating methods and their application to inhabitants of rural and wilderness areas: A critical review

Quantitative soil ingestion studies employing a mass balance tracer approach have been used to provide a defensible means to estimate soil ingestion for human health risk assessments. Past studies have focused on soil ingestion in populations living in urban/suburban environments. There is a paucity of reliable quantitative soil ingestion data to support human health risk assessments of other lifestyles that may be predisposed to ingesting soil, such as agricultural workers or indigenous populations following traditional lifestyles. The results of a preliminary analysis of sampling and analytical variability that would result from assessing activities typical of populations in rural or wilderness areas and conducted over wide areas show that approximately 225 subject days would be required to detect a difference of 20 mg/d in soil ingestion. Given the typically small populations in these areas, future soil ingestion studies should be focused on specific activities with a high potential for soil ingestion.     

Mass diffusion coefficients of oxygenated fuel additives in air

In this work, an experimental system based on digital real-time holographic interferometry for measuring the mass diffusion coefficients of fluid is introduced. The method of processing interference fringe hologram is also introduced thoroughly. By uncertainties analysis and experimental verification, the accuracy of this system is validated. The experimental uncertainties in temperature and mass diffusion coefficient are estimated to be no greater than ± 0.16 K and ± 0.2%, respectively. On this basis, mass diffusion coefficients of two fuel additives: 1,2-dimethoxyethane (ethyleneglycol dimethyl ether, GDME) and 2-methoxyethyl ether (diethylene glycol dimethyl ether, DGM) in air were measured at T = (278.15–338.15) K under atmospheric pressure, and polynomial was fitted by the experimental data.     

小本体PP装置负压回收系统的改造

针对小本体PP装置抽真空排出的含有纯度极高的丙烯气体排入大气这一现状 ,提出了合适的水气分离措施及工艺操作 ,以利于将排空丙烯彻底回收并避免环境污染 ,提高了装置的经济效益     

Quantification of the incorporation coefficient of a reactive gas on a metallic film during magnetron sputtering: The method and results

Reactive Magnetron Sputtering is a complex process and huge efforts are made addressing the understanding of its fundamental phenomena and the simulation of the deposition process by e.g. Particle in Cell/Monte Carlo (PIC/MC). One of the most uncertain parameters in this reactive sputtering process is the incorporation coefficient of the reactive gas in the growing layer, i.e. the real-time sticking coefficient during deposition. In this work, mass spectrometry is used to deliver more insights on this complex matter.Earlier, a method was developed to determine the incorporation coefficient of the reactive gas molecules in the growing metal film, using mass spectrometry combined with thin film analysis techniques (electron probe microanalysis and x-ray photoelectron spectroscopy). This method delivers a global, realistic incorporation coefficient which can be used in models for the reactive sputtering process. In this work, new insights have been added to the classical method. As previously only molecular reactive gas particles were considered, the here described method extends to determine the global incorporation coefficient of all reactive gas particles, i.e. both molecular as atomic. The incorporation coefficient of oxygen gas during the reactive magnetron sputtering of Cu, Al, Mg and Y, is determined. It can be concluded that for the first three metal systems, the obtained incorporation coefficient is mainly determined by the molecular oxygen, while for Y both atomic and molecular oxygen are important. Furthermore, a trend between the difference in electronegativity of the metal and the reactive gas, and the incorporation coefficient can be observed.     

Mass Transfer Enhancement in Double‐Pass,Parallel‐Plate Mass Exchangers under Asymmetric Wall Fluxes

A device involving mass exchangers with a permeable membrane inserted to divide the open duct into two subchannels for conducting double‐pass laminar countercurrent operations under asymmetric wall mass fluxes, which results in a substantial improvement of the mass transfer, has been developed and investigated theoretically. The resultant partial differential equations for such a double‐pass forced‐convection mass transfer problem are referred to as conjugated Graetz problems and solved analytically in this work by using an eigenfunction expansion in terms of power series for the homogeneous part and an asymptotic solution for the inhomogeneous part. The theoretical predictions of mass transfer efficiency improvement in double‐pass, parallel‐plate mass exchangers are obtained by suitably adjusting the permeable membrane location. They are represented graphically and compared with the results from an open duct of a single‐pass operation (without a permeable membrane inserted). The increment of power consumption is also discussed.