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Numerous studies have shown that sorption of organic contaminants in soils is dominated by the natural organic carbon content (C org) of the soil. However, it is still under discussion whether sorption processes are fully reversible or whether an irreversibly sorbed contaminant fraction remains in the soil. This is especially important when considering soil remediation measures and its targets. In multi-stage sorption-desorption batch experiments with TCE, PCE, ortho-xylene and para-xylene and with the sorbents activated carbon, charcoal and a hydrophobic zeolite Y-200, the reversibility of sorption was studied. It could be shown that the structural features of the sorbents are of ample importance for the occurrence of a desorption-resistant fraction. While sorption was mainly reversible for the micro-porous zeolite Y-200 with a rigid pore network, charcoal and the activated carbon showed significant desorption hysteresis. However, following a subsequent sorption step, this fraction eventually desorbs and is re-mobilized. 相似文献
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Yannick Hemberger Nadja Wichtner Christoph Berthold Klaus G. Nickel 《International Journal of Applied Ceramic Technology》2016,13(1):116-124
The relationship between Y2O3 content in tetragonal and cubic ZrO2 phases and the shift of the Raman band at ~645/cm was investigated. With increasing Y2O3 content, the 645/cm Raman band position decreases to lower Raman shift values. A fit of x = Y2O3 content in wt% and y = Raman band position in per cm, was found to be valid for low Y2O3‐stabilized t‐ZrO2, t′′‐ZrO2 transition, and fully stabilized c‐ZrO2. Modeling the change in lattice parameters due to the incorporation of Y2O3 in ZrO2 as obtained from Rietveld‐refined XRD data confirms that the peculiar sigmoidal form of the band shift with Y2O3 content is mainly due to a variation of the amount of oxygen vacancies. The resultant method is highly attractive in fields of Y2O3 determination in ZrO2 materials where a fast, spatially resolved, and nondestructive analysis is required. 相似文献
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Akshay V. Joshi Christoph Dettke Joseph Steingraeber 《Journal of Coatings Technology and Research》2016,13(2):375-383
Gravure is a high throughput printing process, normally associated with speed, quality, and long print runs. It is widely used for printing on shrink films and other substrates. The shrink films, in particular, polyvinyl chloride (PVC) and glycol-modified polyethylene terephthalate (PET-G), are two dominant substrates widely consumed and printed by gravure process. The PVC and PET-G offer different properties which greatly influence the printability. The surface energy of the substrate determines the adhesion and wettability of ink, while electrical properties such as surface and volume resistivity impact electrostatic assist (ESA) performance. The introduction of ESA in gravure further improved the print quality by eliminating dot skips with reduced impression pressure. However, print defects such as print mottle is inevitable. Print mottle occurs due to a discrepancy between substrate, ink, and process parameters which degrade the print quality. These complexities need to be addressed to deliver higher productivity with less print waste. Therefore, the study investigates the effect of process parameters, i.e., substrate type, line screen, air gap (distance between charge bar and impression roller), viscosity, voltage, and speed, and aims to quantify their effect numerically on defect minimization. The Design of Experiments (DOE) was generated for the above-mentioned parameters and analyzed to extract the best combination of process parameters. The optimized setting showed a reduction in solid mottle by 54% and 57% for PET-G and PVC, respectively. 相似文献
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Grundwasser - Chloridazon ist ein Herbizidwirkstoff, der in Deutschland seit 1964 für den Einsatz in der Landwirtschaft zugelassen ist. Er wird hauptsächlich beim Anbau von Rüben,... 相似文献
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Christoph Schmerbauch Jesus Gonzalez‐Julian Robert Röder Carsten Ronning Olivier Guillon 《Journal of the American Ceramic Society》2014,97(6):1728-1735
We report the sintering behavior of nanocrystalline zinc oxide under external AC electric field between 0 and 160 V/cm. In situ acquisition of density by means of laser dilatometry, evaluation of specimen temperature, real‐time measurement of electric field and current help analyze this peculiar behavior. Field strength and blocking electrodes significantly affect densification and microstructure, which was evaluated in the vicinity of the flash event and for the fully sintered material. High current densities flow through the sample at high electric fields, entailing a sudden increment of the temperature estimated to several hundreds of K and an exaggerated grain growth. In contrast, low current density flows through the sample at lower electric fields, which guarantees normal grain growth and highest final density. Macroscopic photoluminescence measurements give insights into the development of the defect structure. Electric fields are expected to enhance defect mobility, explaining the high densification rates observed during the sintering process. 相似文献