Some families of strongly clean rings

A ring R with identity is called strongly clean if every element of R is the sum of an idempotent and a unit that commute with each other. For a commutative local ring R and for an arbitrary integer n?2, the paper deals with the question whether the strongly clean property of M_n(R[[x]]), , and M_n(RC₂) follows from the strongly clean property of M_n(R). This is ‘Yes’ if n=2 by a known result.     

Morphic rings and unit regular rings

A ring R is called left morphic if for every a∈R. A left and right morphic ring is called a morphic ring. If M_n(R) is morphic for all n≥1 then R is called a strongly morphic ring. A well-known result of Erlich says that a ring R is unit regular iff it is both (von Neumann) regular and left morphic. A new connection between morphic rings and unit regular rings is proved here: a ring R is unit regular iff R[x]/(xⁿ) is strongly morphic for all n≥1 iff R[x]/(x²) is morphic. Various new families of left morphic or strongly morphic rings are constructed as extensions of unit regular rings and of principal ideal domains. This places some known examples in a broader context and answers some existing questions.     

分光光度测定铬的灵敏的新方法——铬(Ⅵ)-二溴苯基萤光酮-CPB显色体系的研究

详细研究了Cr(Ⅵ)-二溴苯基萤光酮-CPB的显色反应,发现Cr(Ⅵ)与二溴苯基萤光酮在CPB存在下,pH3.5-5.0时经50℃水浴加热10分钟能生成紫红色组成为1:3的络合物,其最大吸收波长位于586nm处,摩尔吸光系数为1.44×10⁵.Cr(Ⅵ)在0-2.5μg/10ml范围内遵循比尔定律.CyDTA的存在可以消除大量常见离子的干扰.拟定了钢样及水中络的测定方法,并经实际样品的测定,取得较为满意的结果.     

三种六氯铈(Ⅳ)酸有机盐的研究

合成了2,6-二甲基-γ-吡喃酮、咪唑和吡啶铈(Ⅳ)的氯化物,化学式为(C₇H₈O₂H)₂CeCl₆、(C₃H₄N₂H)₂CeCl₆和(C₄H₉NH)₄CeCl₈.采用差热、热重分析法比较了上述三种化合物的热稳定性,并配合以电导、红外、紫外光谱等手段进行了结构分析.     

Ergodicity of the BMAP/PH/s/s+K retrial queue with PH-retrial times

Define the traffic intensity as the ratio of the arrival rate to the service rate. This paper shows that the BMAP/PH/s/s+K retrial queue with PH-retrial times is ergodic if and only if its traffic intensity is less than one. The result implies that the BMAP/PH/s/s+K retrial queue with PH-retrial times and the corresponding BMAP/PH/s queue have the same condition for ergodicity, a fact which has been believed for a long time without rigorous proof. This paper also shows that the same condition is necessary and sufficient for two modified retrial queueing systems to be ergodic. In addition, conditions for ergodicity of two BMAP/PH/s/s+K retrial queues with PH-retrial times and impatient customers are obtained. This revised version was published online in June 2006 with corrections to the Cover Date.     

Tubular bimetal oxysulfide CuMgOS catalyst for rapid reduction of heavy metals and organic dyes

Tubular bimetal oxysulfide CuMgOS catalyst was prepared using a feasible method at a low process temperature of 95°C. X‐ray diffractometry, X‐ray photoelectron spectrometry, field emission‐scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrum, and nitrogen adsorption–desorption isotherms were used for CuMgOS characterizations. The CuMgOS reduction activities were investigated through the reduction of heavy metals of Cr (VI), Pb (II) and Hg (II) solutions, and the organic dyes of rhodamine‐B (RhB), methyl orange (MO) and methylene blue (MB) solutions under dark. The results showed that the CuMgOS prepared with an appropriate N₂H₄ amount for a suitable Cu (I)/Cu (II) ratio exhibited fast reduction activity without adding any reagents, with which the 100 mL Cr (VI), Pb (II) and Hg (II) solutions of 50 ppm were 100% reduced by 20 mg CuMgOS within 4 min, 6 min and 4 min, respectively. The 100 mL RhB, MO and MB solutions of 50 ppm were 100% reduced by 10 mg CuMgOS within 4 min, 5 min and 1 min, respectively, under the existence of NaBH₄. CuMgOS displayed excellent chemical stability for the re‐use tests on heavy metal ions and organic dyes. The excellent performance is attributed to CuMgOS bimetal oxysulfide catalyst with active surface reaction centers to interact with reactants, and the carrier hopping between Cu (I) and Cu (II).     

Study of the cation distributions in Eu doped Sr2Y8(SiO4)6O2 by X-ray diffraction and photoluminescent spectra

The crystal structure and photoluminescent properties of europium doped silicate Sr₂Y₈(SiO₄)₆O₂:Eu³⁺ are reported. The Sr₂Y_8−xEu_x(SiO₄)₆O₂ compounds have typical apatite crystal structures with the P6₃/m space group. The distributions of Eu³⁺ between the two crystallographic sites 4f and 6h in the apatite structure are investigated by the powder X-ray diffraction and Rietveld refinement. Results show that Eu³⁺ ions only occupy the 4f sites when the Eu doping concentration is low (x=0-0.5 in Sr₂Y_8−xEu_x(SiO₄)₆O₂). However, in higher concentrations, Eu³⁺ ions begin to enter the 6h sites as well. The distributions of the Eu³⁺ are also reflected in photoluminescent spectra. The CIE coordinates for Sr₂Y₆Eu₂(SiO₄)₆O₂ are (0.63, 0.37), which is close to the pure red color.     

Degradation behavior and products of malathion and chlorpyrifos spiked in apple juice by ultrasonic treatment

Apple juice (13 °Brix) spiked with malathion and chlorpyrifos (2–3 mg l⁻¹ of each compound) was treated under different ultrasonic irradiations. Results showed that ultrasonic treatment was effective for the degradation of malathion and chlorpyrifos in apple juice, and the output power and treatment time significantly influenced the degradation of both pesticides (p < 0.05). The maximum degradations were achieved for malathion (41.7%) and chlorpyrifos (82.0%) after the ultrasonic treatment at 500 W for 120 min. The degradation kinetics of both pesticides were fitted to the first-order kinetics model well (R²  0.90). The kinetics parameters indicated that chlorpyrifos was much more labile to ultrasonic treatment than malathion. Furthermore, malaoxon and chlorpyrifos oxon were identified as the degradation products of malathion and chlorpyrifos by gas chromatography–mass spectrometry (GC–MS), respectively. The oxidation pathway through the hydroxyl radical attack on the PS bond of pesticide molecules was proposed.     

像散法离焦检测中的像散透镜参数设计

推导出了离焦量与聚焦误差信号功率的关系式。利用MATLAB软件仿真,详细分析了像散透镜系统各个参数对离焦量、灵敏度、光斑大小等的影响,得到了像散圆透镜与像散柱透镜焦距之间的距离关系。结果发现聚焦物镜和探测器参数对最小离焦量、灵敏度、精度有决定性的影响。提出了像散透镜系统各光学参数选择的原则和方法,并以德国Silicon Sensor公司的QP50-6型四象限探测器为例,详细分析了离焦量与聚焦误差信号功率的线性关系。这些工作对建立满足应用对象要求的像散法离焦检测系统具有重要的指导意义。     

CrSi(2) hexagonal nanowebs

Single-crystalline CrSi(2) nanostructures with a unique hexagonal nanoweb morphology have been successfully synthesized for the first time. These nanowebs span 150-200 nm and are composed of <112?0> nanowire segments with a thickness of 10-30 nm. It is proposed that surface charges on the {101?0} sidewalls and the minimization of electrostatic energy induce the nanoweb formation. Calculations of the electrostatic energies were used to predict the transitions between different modes of bending, which agreed well with the experimental observations.