Degradation of 2,4-D By Ozone And Light

The decomposition of 2,4-dichlorophenoxyacetic acid in aqueous solutions has bsen studied using ozone and ultraviolet radiation at different pH, ozone production, and initial concentration of pesticide. A mathematical model which incorporates the rate of mass transfer of ozone, the oxidation kinetics of 2,4-D and the kinetics of formation and oxidation of the intermediates was used. A global rate constant was calculated and an empirical equation which correlated that constant with ozone production, initial concentration of 2,4-D and pH at the same temperature was determined.     

A three-dimensional model for suspension-to-membrane-wall heat transfer in circulating fluidized beds

A three-dimensional model is proposed for both furnace-side and wall-side heat transfer in circulating fluidized beds with membrane walls. Following previous publications (Int. J. Heat Mass Transfer (2003a, b)), a core-annulus flow structure is employed in the model, with consideration of the membrane wall influence on bed hydrodynamics. The model couples radiation, conduction and convection on the furnace side to conduction and convection on the wall side. Radiation in the wall layer is simulated by the moment method. A finite-element method is employed to solve the set of non-linear, partial differential equations. The solution is demonstrated for a typical example. The model gives predictions of suspension-to-wall heat transfer which show satisfactory agreement with published experimental data.     

Ozone-Based Advanced Oxidation Processes for the Decomposition of N-Methyl-2-Pyrolidone in Aqueous Medium

The present study investigates the decomposition of N-Methyl-2-Pyrolidone (NMP) using conventional ozonation (O₃), ozonation in the presence of UV light (UV/O₃), hydrogen peroxide (O₃/H₂O₂), and UV/H₂O₂ processes under various experimental conditions. The influence of solution pH, ozone gas flow dosage, and H₂O₂ dosage on the degradation of NMP was studied. All ozone-based advanced oxidation processes (AOPs) were efficient in alkaline medium, whereas the UV/H₂O₂ process was efficient in acidic medium. Increasing ozone gas flow dosage would accelerate the degradation of NMP up to certain level beyond which no positive effect was observed in ozonation as well as UV light enhanced ozonation processes. Hydrogen peroxide dosage strongly influenced the degradation of NMP and a hydrogen peroxide dosage of 0.75 g/L and 0.5 g/L was found to be the optimum dosage in UV/H₂O₂ and O₃/H₂O₂ processes, respectively. The UV/O₃ process was most efficient in TOC removal. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of NMP in wastewater.     

The Chemistry of Water Treatment Processes Involving Ozone,Hydrogen Peroxide and Ultraviolet Radiation

Advanced oxidation processes are defined as those which involve the generation of hydroxyl radicals in sufficient quantity to affect water purification. The theoretical and (practical yield of OH from O₃ at high pH, 0₃/H₂0₂, O₃/UV and H₂O₂/UV systems is reviewed. New data is presented which illustrates the importance of direct photolysis in the O₃/UV process, the effect of the H₂0₂:0₃ ratio in the O₃/H₂O₂ process, and the impact of the low extinction coefficient of H₂O₂ in the H₂0₂/UV process.     

底部局部辐射加热窑炉内温度场数值模拟

提出了底部局部辐射加窑炉内温度场数值分析的控制方程组，分别对平面加热及半圆柱形加热面两种算例进行了数值计算，得了影响烤花烤窑炉内温度场均匀性的主要因素和有加热面发射率，加热面形状，加热面相对位置及窑炉墙体热阻和墙体与外界的换热热阻。     

硅氮聚合物交联的室温硫化橡胶的研究Ⅰ．热稳定性的研究

本文利用硅氮聚合物作文联剂使双组分缩合型室温硫化硅橡胶在不需要催化剂存在下就能交联硫化，通过时硫化胶老化后的热失重、交联密度和力学性能的测定，表明这种硫化胶的耐温性能由２００℃提高到３５０℃。对硫化胶的降解动力学研究表明：降解反应活化能由７０ｋＪ／ｍｏｌ提高到３３０ｋＪ／ｍｏｌ，这是由于消除了端基引发的主链降解。     

Fabrication and characterization of APT specimens from high dose heavy ion irradiated materials

The next generations of advanced energy systems will require materials that can withstand high doses of irradiation at elevated temperatures. Therefore, a methodology has been developed for the fabrication of high-dose ion-irradiated atom probe tomography specimens at a specific dose with the use of a focused ion beam milling system. The method also enables the precise ion dose of the atom probe tomography specimen to be estimated from the local concentration of the implanted ions. The method has been successfully applied to the characterization of the distribution of nanoclusters in a radiation-tolerant 14YWT nanostructured ferritic steel under ion irradiation to doses up to 400 displacements per atom.     

基于表面波激励的等离子体单极天线的研究

等离子体天线是一种新型的非金属介质天线,在电控、隐身等方面具有优异性能.在等离子体天线基本工作原理的基础七,利用非磁化冷等离子体理论,为了研究柱型等离子体表面波的产生方式,得出了维持稳定等离子体的能量关系.又采用等离子体表面波的色散关系理论,计算了不同激励功率下表面波波数沿等离子体天线轴向的变化,通过改变激励功率和碰撞频率来控制等离子体天线方向图.结果表明,等离子体天线具有良好的辐射性能,并且通过改变激励源功率可以实现等离子体天线参数的电控.     

Functionalization of multi-walled carbon nanotubes by radiation-induced graft polymerization in aqueous solution

A facile strategy for the preparation of water-soluble multi-walled carbon nanotubes (MWCNTs) in aqueous solution is proposed, where MWCNTs were treated by the concentrated mix acid and then functionalized by simultaneous radiation-induced graft polymerization of acrylic acid under the γ-ray. The structure of the grafted MWCNTs (denoted as MWCNT-g-PAAc) is characterized by means of FT-IR, ^lH NMR, Raman spectroscopies, TGA analysis, and TEM imaging. The degree of grafting was dependent on the reaction conditions such as the monomer concentration and the inhibitor concentration. The stability of the aqueous solution of MWCNT-g-PAAc is highly improved, where the solution is stable for more than 30 days at the concentration 1.5 g/L.     

Retrospective analysis for evaluation of the value of contrast-enhanced MRI in patients treated with breast conservative therapy

Purpose The aim of this study was to assess the value of contrast-enhanced (c.-e.) MRI in the follow-up of patients with conservatively treated breast cancer since detection and exclusion of malignancy may interfere significantly with posttherapeutic changes within the treated breast. Material and methods A total of 207 patients with a history of limited surgery and radiation therapy underwent MR imaging, 40 patients were examined 0–12 months and 167 patients were examined later than 12 months after radiotherapy. Suspicious or indeterminate findings were suggested by clinical examination or conventional imaging in 80 studies. In 127 women, MRI was performed within breast tissue that was difficult to assess due to scarring or dense breast tissue. Results Recurrent carcinoma was confirmed in 27 patients by surgical biopsy. All 27 carcinomas, except for one with a slow signal increase, demonstrated early rise of signal intensity on dynamic T1-weighted contrast enhanced images. During the first year after therapy, the diagnostic accuracy could not be improved by additional use of c.-e. MRI. Differentiation between posttherapeutic changes and recurrent carcinoma was frequently not possible because of strong and sometimes early and ill-circumscribed enhancement. Later than 12 months after therapy enhancement decreased significantly, thus the false positive calls could be reduced from 49 (conventional imaging) to 12 (conventional imaging plus MRI). A total of 12 of 26 recurrences and multifocality in 4/5 cases were diagnosed by MR imaging alone at this time interval. Conclusion In the first year after therapy, c.-e. MRI is only indicated in selected cases. The results later than 12 months emphasize that c.-e. MRI may contribute significant additional information. It allows better distinction of posttherapeutic fibrosis from recurrent carcinoma and proved to be able to detect recurrent disease more sensitive and at an earlier stage.