Enhancement of dye sonochemical degradation by some inorganic anions present in natural waters

The sonochemical degradation rate of the charged substrates Acid Blue 40 (AB40) and methylene blue (MB) is enhanced by scavengers of hydroxyl radicals such as bicarbonate, carbonate, bromide, iodide and (only in the case of AB40) nitrite. No rate variation was observed with chloride, nitrate or sulphate, excluding a mere ionic strength effect. Oxidation of bicarbonate, carbonate, bromide, iodide and nitrite yields the corresponding radicals CO₃⁻, Br₂⁻, I₂⁻ and NO₂, reactive but less than OH. Degradation enhancement can occur if these radicals are sonochemically formed on the surface of the collapsing cavitation bubbles and undergo there radical–radical recombination at a lesser extent than OH. In this way the radicals would be more available than OH for substrate degradation, both at the bubble surface and in the solution bulk, which could more than compensate for their lower intrinsic reactivity. The varied reactivity toward different substrates of the sonochemically formed radical species could then explain why nitrite inhibits MB degradation while enhancing that of AB40. The sonochemical formation of Br₂⁻, I₂⁻ and NO₂ can give rise to halogenation and nitration in addition to oxidation processes. In fact bromo-, iodo- and nitrophenols were detected upon sonication of phenol in the presence of the corresponding anions, but only at quite elevated concentration values of nitrite, bromide or iodide (above 10 mM). Formation of harmful halogeno- and nitroderivatives could therefore take place on sonication of some wastewater rather than of typical natural waters.     

Oxidation of accident tolerant fuel candidates

In this study, the oxidation of various accident tolerant fuel candidates produced under different conditions have been evaluated and compared relative to the reference standard – UO₂. The candidates considered in this study were UN, U₃Si₂, U₃Si₅, and a composite material composed of UN–U₃Si₂. With the spark plasma sintering (SPS) method, it was possible to fabricate samples of UN with varying porosity, as well as a high-density composite of UN–U₃Si₂?(10%). Using thermogravimetry in air, the oxidation behaviors of each material and the various microstructures of UN were assessed. These results reveal that it is possible to fabricate UN to very high densities using the SPS method, such that its resistance to oxidation can be improved compared to U₃Si₅ and UO₂, and compete favorably with the principal ATF candidates, U₃Si₂, which shows a particularly violent reaction under the conditions of this study, and the UN–U₃Si₂?(10%) composite.     

Novel ESIPT fluorescent benzazolyl-4-quinolones: Synthesis, spectroscopic characterization and photophysical properties

Two, novel, benzazolyl-quinolone heterocycles, fluorescent by virtue of intramolecular proton transfer mechanism in the excited state (ESIPT), were obtained using the Gould-Jacobs reaction. The intramolecular cyclization step in the preparation of the anilinomethylene malonate derivatives was carried out using polyphosphoric acid, heat transfer fluids (Dowtherm A Fluid, mineral oil and diphenyl ether) as well as tandem methodology, at temperatures ranging from 180 °C to 250 °C. Tandem methodology provided better yields and lower by-product formation. The synthesized quinolones were characterized using elemental analysis, IR, ¹³C and ¹H NMR spectroscopy. Photophysical behaviour was studied using UV–Vis and steady-state fluorescence, both in solution and in solid state. The quinolones were fluorescent in solution in the orange-red region (500–800 nm), under UV radiation, and displayed a large Stokes shift (165–194 nm).     

New fluorescent monomers and polymers displaying an intramolecular proton‐transfer mechanism in the electronically excited state (ESIPT). IV. Synthesis of acryloylamide and diallylamino benzazole dyes and its copolymerization with MMA

Six new fluorescent monomers were synthesized by reaction of 2‐(5′‐amino‐2′‐hydroxyphenyl)benzazole derivatives with acryloyl chloride and allyl bromide. UV–vis and steady‐state fluorescence in solution were used to characterize its photophysical behavior. The monomers are fluorescent in the blue, green, yellow, and red region, with a large Stokes shift between 92 and 226 nm. A dual fluorescence ascribed to a conformational equilibrium in solution in the ground state dependent on the solvent polarity could be observed in the fluorescence emission spectra of the monomers. The radical polymerization of the monomers with methyl(methacrylate) allowed the production of fluorescent polymers in the blue–green region, with good optical and thermal properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

论柔性机构的应用

  柔性机构的应用越来越广泛,且在许多任务中能有效地替代常规刚体机构.所介绍的柔性结构分类产生于依尔墨瑙技术大学多年研发柔性机构的工作成果.这种对柔性结构的介绍有助于使用者提出任务并为此有目的地应用柔性机构.此外,分类还指出了柔性机构未来发展的可能性.     

An improved gravimetric method applied to co-processing of polyethylene terephtalate and petroleum blend using HY zeolite as a catalyst

The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures, an increase in conversion to about 25–30% was observed. At temperatures of 400 and 500 °C, conversions above 90% were obtained for the two samples, with a subsequent reduction in the activation energy, from 76 kJ mol^?1 (PET) to 56 kJ mol^?1 (PET–oil/HY). The decrease in the activation energy proved the efficiency of the HY zeolite and the synergistic effect when PET was blended to the oil for the catalytic co-processing, proving to be a viable alternative for the chemical recycling of PET in the petroleum industry.     

Load-strength simulation of plastic mouldings

The load-strength theory is used to simulate the relations between the reliability, the safety factors used in the mechanical design and the different material conditions caused by batch variations in raw material, the injection moulding process and the mould design.     

Product certification and standards for testing

This note is a short tutorial overview on the standardization activities of interest for testing, together with an overview on the role of testing in the European open market. Activities and problems are listed and discussed. A number of reliability and test standards are listed.