Post-annealing effects on structural and magnetic properties of Mn–N codoped ZnO thin films

The sputtered ZnO:Mn thin films were implanted with nitrogen ions (N⁺) and subsequently annealed at different temperatures up to 800 °C in N₂ atmosphere. The structural and magnetic properties of the samples were systematically investigated. Both x-ray diffraction and Raman analyses reveal that all the films are of the wurtzite structure of ZnO with no distinct evidence of secondary phases. X-ray photoelectron spectroscopy studies indicate that both Mn²⁺ and N³⁻ ions were incorporated into ZnO lattice successfully. While the films without nitrogen ions show paramagnetic behavior, ferromagnetism with clear hysteresis at 300 K is observed in Mn–N codoped ZnO films. Most importantly, we also found that the magnetic behavior of the codoped ZnO is very sensitive to the annealing temperature due to its effect on the activation of nitrogen ions. The strongest ferromagnetism is obtained in the films with the highest amount of nitrogen ions acceptors. Our results support the predication that the ferromagnetic ZnO:Mn²⁺ should be more stable of a hole-rich environment by theory.     

数字化钢球磨煤机控制系统商品化实施和效果

从描述商品化的内涵入手,论述数字化钢球磨煤机在线决策控制系统(DMS2800)商品化开发目标是适应于老厂改造和新厂设计的各类系统,其系统可使设备达到连续运行,提高投入率,磨制每t煤粉可节电3kW·h以上。详述实现商品化的措施及现场应用效果和经验。     

Fitting Triangular B-Splines to Functional Scattered Data

Scattered data is, by definition, irregularly spaced. Uniform surface schemes are not well adapted to the locally varying nature of such data. Conversely, Triangular B-Spline surfaces 2 are more flexible in that they can be built over arbitrary triangulations and thus can be adapted to the scattered data. This paper discusses the use of DMS spline surfaces for approximation of scattered data. A method is provided for automatically triangulating the domain containing the points and generating basis functions over this triangulation. A surface approximating the data is then found by a combination of least squares and bending energy minimization. This combination serves both to generate a smooth surface and to accommodate for gaps in the data. Examples are presented which demonstrate the eftectiveness of the technique for mathematical, geographical and other data sets.     

Growth and Magnetic Properties of Sol-Gel Derived Co-Doped ZnO Thin Film

Zn1-xCoxO films were grown on glass by sol-gel spin coating process. A homogeneous and stable Zn1-xCoxO sol was prepared by dissolving zinc acetate dihydrate, cobalt acetate tetrahydrate and aluminium chloride hexahydrate as solutes in solution of isopropanol and monoethanolamine. The films were postheated and vacuum annealed, and investigated for c-axis preferred orientation and electromagnetic properties. Zn1-xCoxO films with different Co concentrations were oriented well along the c-axis, especially the Zn1-xCoxO film with 10% Co(atom fraction) was highly c-axis oriented. The transmittance spectra show that Zn1-xCoxO films occur d-d transition and sp-d exchange interaction between Co2 ions. The electrical resistivity of the films at 10% Co had the lowest value because the crystallite size became largest and the crystallinity of the c-axis was improved. X-ray photoelectron spectroscopy and alternating gradient magnetometer analyses indicated that no Co metal cluster was formed, and the ferromagnetism at room temperature appeared. The characteristics of the electrical resistivity and room temperature ferromagnetism of sol-gel derived Zn1-xCoxO films suggest a potential application of dilute magnetic semiconductor devices.     

海砂中氯离子含量的影响因素研究

试验研究了砂水比、海水氯离子含量、海砂含水率及颗粒粒径等因素对海砂中氯离子含量的影响.结果表明:海砂中氯离子含量分别与海水氯离子含量及海砂含水率显著线性相关;堆积状态下的海砂,其含水率沿堆积高度呈递减规律,含水率稳定值对应的临界高度约为40cm;海水氯离子含量、海砂含水率及颗粒粒径等因素对海砂氯离子含量的影响规律均可用相应的数学关系来表征.     

A study on volatile organic sulfide causes of odors at Philadelphia's Northeast Water Pollution Control Plant

Volatile organic sulfide (VOS) causes of odors were studied at Philadelphia's Northeast Water Pollution Control Plant between September 11 and November 25, 2003. Results showed that dimethyl sulfide (DMS) dominated the VOS pool whenever VOS concentration rose above the background level (<50 microg/L). Methanethiol was generally less than 10% of VOS and it was mainly found at sites with limited or reduced dissolved oxygen (DO). Dimethyl disulfide occupied approximately 1% of the VOS and was often not detectable. Carbon disulfide was not detected. The concentrations of DMS varied by three orders of magnitude, ranging from <5 to 1260 microg/L. High concentrations of DMS, averaging 419 and ranging from <5 to 1000 microg/L, were generally found in return activated sludge. The DMS concentration in the primary effluent ranged from <5 to 729 microg/L and averaged 245 microg/L. Concentrations of DMS in the aeration tank (AT) with high DO were from <5 to 997 microg/L with an average of 250 microg/L. However, DMS concentrations in the AT representing anaerobic conditions were as high as 1260 microg/L. The estimated average purge efficiency of DMS was about 78%, which required a DMS production rate of 108 microg/Lh(-1) to keep the analyzed concentration in the AT. While a valid but weak statistical relationship between acetone and DMS was observed, there was no strong evidence to support that the methylation of hydrogen sulfide with acetone could be the mechanism for the DMS formation. Instead, DMS production was found to be associated with the characteristics of incoming wastewater. Thus, a VOS precursor was believed to be present in the incoming wastewater, which warranted a need for further investigation.     

Effect of Operating Pressure on the Application of Multiple Cyclones in Dense Medium Separation (DMS) Plant

In order to meet the market demands for minerals, it is necessary that large volumes of ores be treated at a rapid rate, and this has led to the use of multiple cyclones (in parallel) in the dense medium separation (DMS) plant since the single largest efficiently used cyclone (710 mm in diameter) can only process approximately 400 m³/h of material. However, the use of multiple cyclones came with a few problems that are all centered on the split of the ore feed and transport medium amongst the number of cyclones used. Poor splits often lead to poor separations, especially when treating ores with a high quantity of near-gravity material. This study therefore, focuses on the effects of operating pressure on the stability and efficiency of the cyclones. The effects of pressure on the stability and distribution of the ore in the cyclones were also investigated in this study. The analyses of the results obtained indicate that the circulating medium was stable with percentage stability in the range of 3 to 12%, with average medium stability of 8.3%. The results also show that changes in the circulating medium density and mixing box operating level had little effect on the cyclone pressure. The simulated results indicate that changes larger than 5% may adversely affect cyclone pressures. Tracer analysis was used to determine the efficiency, and its results show that the cyclones were cutting at a very high density cut point, which was due to the high operating head of the cyclones at 16D. It was discovered that operating the cyclone at maximum head of 12D to bring down the cut point reduce the wear rate on the cyclones. The tromp curves obtained from operating the cyclones at a lower pressure gave an average mean probable error of 0.048 (0.05 approximately) and an average cut point of 3.13. This indicates that the cyclones operate fairly similarly with very good separation efficiencies.     

差分迁移谱(DMS)研究进展

近年来,差分迁移谱(DMS)在生化快速检测领域的应用日益广泛,随着研究的深入,在小型化、提高分辨率方面取得了较大进展,并在质谱预分离方面展现出巨大的潜力。本文针对单通道和多通道两种结构的DMS传感器,介绍了国内外最新的研究与仪器研制进展,详细阐述了DMS传感器的结构特征及制造方法,并对DMS传感器的发展前景进行了展望。     

Three-components organic–inorganic hybrid materials as protective coatings for wood: Optimisation,synthesis, and characterisation

The present work explores new solutions for the development of functional flame-resistant hybrid coatings for wood, by using oxocluster-reinforced hybrid materials. Hybrid coatings and bulk materials were produced by photopolymerisation of 3-methacryloxypropyltrimethoxysilane (MAPTMS) with methylmethacrylate (MMA) in the presence of the dimeric oxocluster (Zr₆O₄(OH)₄(OOCCH₂CHCH₂)₁₂(n-PrOH)]₂·4(CH₂CHCH₂COOH), (Zr12), characterised by the presence of 12 vinylacetate groups for each molecules. The molar ratios among silane, MMA monomer and oxocluster were changed to optimise the best performing formulation. The final molar ratio chosen for the spray deposition of the coatings under inert atmosphere and for the preparation of the bulk specimens was MAPTMS:MMA:Zr12 = 1:3:0.008. Attenuated Total Reflectance-Fourier Transform Infra Red (ATR-FTIR) spectroscopy and Differential Scannig Calorimetry (DSC) were used in time-resolved fashion to optimise the photopolymerisation time, resulting to be 20 min. The polymerisation of the organic part and the condensation of the siloxane groups were investigated by the combined use of DSC, Fourier Transform Infra-Red (FTIR) and solid state Nuclear Magnetic Resonance (NMR) spectroscopies, showing that, whereas a complete organic polymerisation degree was reached, the condensation of the silica component was not completed. Dynamical Mechanical Spectroscopy (DMS) evidenced that: (1) the copolymerisation of the silane with the Zr12 oxocluster without MMA yields materials with very poor mechanical thermo-properties; (2) the Zr12 oxocluster copolymerised with MMA gives very stiff but fragile hybrids; (3) the ternary system yields instead flexible materials, which are endowed with outstanding thermo-mechanical properties. The optimised formulation was used for the deposition of coatings on wood (Larex), which were analysed by Scanning Electron Microscopy (SEM), contact angles measurements and tested toward flame-resistance.     

配电管理系统的认知体系结构

分析了配电管理系统(DMS)研发中遇到的问题,提出从信息加工的角度整体研究、实现和评价DMS。为实现该目的,在认知科学的基础上,建立DMS认知体系结构(DMSCA)的概念模型和逻辑模型,分别对该体系结构的整体性、自身调整性和转换性进行分析,介绍了DMSCA所支持的基本设计思想。最后,讨论了DMSCA的实际应用,重点介绍了基于DMSCA的原型法,用于指导DMS的开发。DMSCA属于一种高层次的软件框架设计方法,可用于对DMS进行统一规划,构建系统的整体框架,为研究与开发提供了新的视角与方法。