The Analyses of Luminescent Properties and Structure of the Tetragonal Phase of Y2WO6:Eu3+ doped Phosphor

The structural, electronic and luminescent properties of the tetragonal phase of Y₂WO₆ phosphors doped with different amounts of Eu³⁺ have been studied. All samples were synthesized via solid-state methods, using NaCl as mineralizer. Through Rietveld refinement was found that the Eu³⁺ cations only occupy the Y1 (2c) sites of the host-matrix. The thermal stability of the undoped sample was investigated using simultaneous TG-DSC thermal analyses. The SEM analysis revealed that the doped and the undoped samples have tendency to form microcrystals with smooth surfaces and in both cases it is possible to observe some agglomerates of nanoparticles. Periodic Density Functional Theory calculations (DFT) were carried out to investigate the electronic properties of the undoped material; these results show good agreement with the experimental ones. The emission spectra of all doped-samples are dominated by the electric dipole transition (ED) ⁵D₀ → ⁷F₂ located at 613 nm, which indicates that the Eu³⁺ ions are located in non-centrosimetric sites in the host-structure.     

Robust location of new housing developments using a choice model

We consider the issue of choosing a subset of locations to construct new housing developments maximizing the satisfaction of potential buyers, which has not been previously studied in the literature. The allocation of demands to the selected locations is modeled by a choice model, based on the distance to the location, real-estate prices and incomes. We study two robust counterparts of the optimal location problem, where uncertainty lies on demand volumes for the first one, and on customer preferences for the second one. In both cases, the parameters subject to uncertainty appear both in the objective function and constraints. The second robust model combines a scenario-based approach with nominal, price-centric and distance-centric scenarios on customers preferences, and an uncertainty budget approach that limits the number of customers that can deviate from the nominal scenario. We show that the subproblem of finding the worst-case deviation of parameters subject to uncertainty is tractable and leads to linear formulations of the robust problem. Computational experiments conducted on instances of the Paris region show that the average loss of value of the robust solution is reasonably low when compared to the optimal solution of deviated instances. We also derive insights for the new housing development issue.     

New pyrazolino and pyrrolidino[60]fullerenes: the introduction of the hydrazone moiety for the formation of metal complexes

The [3 + 2] cycloaddition reaction of C₆₀ with pyridine‐derived hydrazones (acting as dipolar reagents) was successfully conducted resulting in fullerene derivatives 5a , 5b . The compounds were characterized by means of NMR, UV–Vis spectroscopy, and X‐ray crystallography. The electrochemical behavior was also investigated. The fulleropyrazoline 5a exhibits anodically shifted reduction potentials of about 100 mV when compared with those for C₆₀, whereas 5b exhibits cathodic shifts relative to pristine C₆₀. The complexation reaction of 5b with metallic ions (Zn²⁺, Cd²⁺, and Fe²⁺) was achieved. Job and Benesi–Hildebrand analysis confirmed the formation of complexes with a molar ratio of 1:1 and binding constants between 2.26 × 10⁵ and 1.59 × 10⁵ M^?1. Electrochemistry of these complexes showed a marked influence of the metal ion on the reduction potentials. Copyright © 2016 John Wiley & Sons, Ltd.     

Lifting, tilting and fractional programming revisited

Lifting, tilting and fractional programming, though seemingly different, reduce to a common optimization problem. This connection allows us to revisit key properties of these three problems on mixed integer linear sets. We introduce a simple common framework for these problems, and extend known results from each to the other two.     

铸造铝青铜合金Cu-14Al-4Fe-Mn的摩擦磨损性能

用往复式摩擦磨损试验机考察了新型高强度、高耐磨性铸造铝青铜合金Cu-14Al-4Fe-Mn(代号HSWAB)的摩擦磨损性能,利用形貌扫描电子显微镜观察分析了合金磨损表面形貌,探讨了其磨损机理.结果表明,HSWAB合金在干摩擦和油润滑条件下的摩擦磨损性能及磨损机理存在明显差异.在干摩擦条件下,合金中脱落的硬质点及氧化物等磨粒导致较为严重的磨粒磨损,摩擦系数高、磨损率大,主要磨损机理为磨粒磨损、粘着磨损、氧化磨损及疲劳磨损.在油润滑条件下,摩擦系数和磨损率均显著降低,疲劳磨损和氧化磨损受到抑制,主要磨损机理为磨粒磨损和粘着磨损.Cu-14Al-4Fe-Mn合金在油润滑条件下的摩擦系数低达0.08,磨损率低达3.7×10-6g/m,是一种优良的耐磨材料.     

Insecticidal,Repellent and Antifeedant Activity of Essential Oils from Blepharocalyx cruckshanksii (Hook. & Arn.) Nied. Leaves and Pilgerodendron uviferum (D. Don) Florin Heartwood against Horn Flies,Haematobia irritans (Diptera: Muscidae)

Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC₅₀ values for B. cruckchanksii essential oil of 3.58 µL L⁻¹ air at 4 h, and for P. uviferum essential oil of 9.41 µL L⁻¹ air and 1.02 µL L⁻¹ air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.     

乙酸铵离心交换法和乙酸钙离心交换法测定土壤阳离子交换量

土壤阳离子交换量(CEC)的测定在农业中有重要的意义,对农业行业标准NY/T295—1995和NY/T1121.5—2006中的离心交换法测定土壤中CEC值的方法进行了优化,讨论了不同pH值的土壤样品对两种方法的选择依据,分析了CEC值测定重现性较差的原因。结果表明,pH值的范围是方法选择的重要依据,pH7.0的样品适合用乙酸铵离心交换法,pH≥7.0的样品则适用乙酸钙离心交换法。优化后方法的准确度和精密度有了较大的改善,实验中对各步骤的优化缩短了约40%的操作时间,减少工作量,适合于批量样品的准确测定。     

纳氏试剂测定水中氨氮影响因素的探讨

对国家生活饮用水标准检验方法"GB/T5750—2006"中涉及到的水中氨氮的检测条件进行了探讨,讨论了样品的采集与保存,影响显色、空白值的各项因素,并提出相应的解决办法。对国家标准物质以及实际样品的验证表明,方法的相对误差为0.03%~1.5%,相对标准偏差RSD为0.55%~5.3%,准确度也能满足分析要求,对国家标准方法进行了补充与细化,在实际工作中有参考价值。     

Equilibrium partitioning of a simple fluid in a matrix-filled cylindrical pores with adsorbing walls: A grand canonical Monte Carlo study

We have studied a model of a hard sphere fluid adsorbed in a cylindrical pore filled with quenched disordered matrix of hard sphere particles using Grand canonical Monte Carlo simulations. The interactions between matrix species and pore walls are assumed of a hard sphere type. However, the pore walls exert a short-range attraction upon adsorbed fluid particles. We discuss the adsorption isotherms and the density profiles of fluid particles in pores with different microporosity for several values of the pore radius. We have observed that like in homogeneous microporous media the adsorption increases with increasing porosity. However, trends of behavior of the isotherms also reflect layering of adsorbed fluid. The data obtained in this study may serve as a benchmark for the development of the theory of confined quenched-annealed systems and for computer simulation investigation of models permitting phase transitions in pores. This project has been supported in parts by DGAPA of the UNAM under research grant IN111597, by the National Council for Science and Technology (CONACyT), grant No. 25301-E.