Determination of pesticides in compost by pressurized liquid extraction and gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric method was developed for the determination of pesticides in compost. The investigated pesticides included two fungicides, two herbicides and 10 insecticides. The pesticides were extracted from the compost by pressurized liquid extraction. The extract was cleaned up by a partition between hexane and acetonitrile followed by a dispersive solid-phase extraction using a porous carbon made from Moso bamboo (Phyllostachys pubescens). The overall recoveries were 81-104% and the relative standard deviations (RSDs) ranged from 2.4 to 12%. The minimum detectable concentrations were 0.02-0.04 microg g(-1). This method was successfully applied to a compost sample from food waste as well as commercial compost.     

Synthetic studies on chemotherapeutics. III. Synthesis of the 6,9-dihydro-9-oxo-1H- and 2H-pyrazolo[3,4-f]quinoline-8-carboxylic acid derivatives [studies on the syntheses of heterocyclic compounds. Part 718 ]

1H- and 2H-Pyrazolo[3,4-f]quinolines were synthesized in order to get an antibacterial compound by two different methods from 6-nitro- and 6-aminoindazole.     

Higher order fields for damaged nonlinear antiplane shear notch, crack and inclusion problems

Damaged nonlinear antiplane shear problems with a variety of singularities are studied analytically. A deformation plasticity theory coupled with damage is employed in analysis. The effect of microscopic damage is considered in terms of continuum damage mechanics approach. An exact solution for the general damaged nonlinear singular antiplane shear problem is derived in the stress plane by means of a hodograph transformation, then corresponding higher order asymptotic solutions are obtained by reversing the stress plane solution to the physical plane. As example, traction free sharp notch and crack, rigid sharp wedge and flat inclusion, and mixed boundary sharp notch problems are investigated, respectively. Consequently, higher order fields are obtained, in which analytical expressions of the dominant and second order singularity exponents and angular distribution functions of the near tip fields are derived. Effects of the damage and hardening exponents of materials and the geometric angle of notch/wedge on the near tip quantities are discussed in detail. It is found that damage leads to a weaker dominant singularity of stress, but to little stronger singularities of the dominant and second order terms of strain compared to that for undamaged material. It is also seen that damage has important effect on the angular distribution functions of the near tip stress and strain fields. As special cases, higher order analytical solutions of the crack and rigid flat inclusion tip fields are obtained, respectively, by reducing the notch/wedge tip solutions. Effects of damage and hardening exponents on the dominant and second order terms in the solutions of the crack and inclusion tip fields are discussed.     

Wave band gaps in two-dimensional piezoelectric/piezomagnetic phononic crystals

In this paper, the elastic wave propagation in phononic crystals with piezoelectric and piezomagnetic inclusions is investigated taking the magneto-electro-elastic coupling into account. The electric and magnetic fields are approximated as quasi-static. The band structures of three kinds of piezoelectric/piezomagnetic phononic crystals—CoFe₂O₄/quartz, BaTiO₃/CoFe₂O₄ and BaTiO₃–CoFe₂O₄/polymer periodic composites are calculated using the plane-wave expansion method. The piezoelectric and piezomagnetic effects on the band structures are analyzed. The numerical results show that in CoFe₂O₄/quartz structures, only one narrow band gap exists along the Γ–X direction for the coupling of xy-mode and z-mode for the filling fraction f being 0.4; while in BaTiO₃/CoFe₂O₄ composites, only one narrow band gap exists along the Γ–X direction forxy-mode and no band gap exists for z-mode as the filling friction f is 0.5. Moreover, for the new type of magneto-electro-elastic phononic crystal—BaTiO₃–CoFe₂O₄/polymer periodic composite, the band gap characteristics are more superior in the whole considered frequency regions due to the big contrast of the material properties in the two constituents and the effects of the piezoelectricity and piezomagneticity on the band gap structures are remarkable.     

WAVE LOCALIZATION IN RANDOMLY DISORDERED PERIODIC PIEZOELECTRIC RODS WITH INITIAL STRESS

The elastic wave localization in disordered periodic piezoelectric rods with initial stress is studied using the transfer matrix and Lyapunov exponent method. The electric field is approximated as quasi-static. The effects of the initial stress on the band gap characteristics are investigated. The numerical calculations of localization factors and localization lengths are performed. It can be observed from the results that the band structures can be tuned by exerting the suitable initial stress. For different values of the piezoelectric rod length and the elastic constant, the band structures and the localization phenomena are very different. Larger disorder degree can lead to more obvious localization phenomenon.     

Band gaps of elastic waves in three-dimensional piezoelectric phononic crystals with initial stress

In this paper, the stop band properties of elastic waves in three-dimensional piezoelectric phononic crystals with initial stress are studied taking the mechanical and electrical coupling into account. The band gap characteristics for three kinds of lattice arrangements (i.e. sc, bcc and fcc) are investigated by the plane wave expansion (PWE) method. Regarding the variables of mechanical and electrical fields as the elements of the generalized state vector, the expression of the generalized eigenvalue equation for three-dimensional piezoelectric periodic structures is derived. Numerical calculations are performed for the PZT-2/polymer and ZnO/polymer phononic crystals. It can be observed from the results that the fcc lattice is more favorable to create the stop band than the sc and bcc lattices for the piezoelectric phononic crystals, which has also been proved for the pure elastic periodic structures. Compared with the PZT-2/polymer systems, the band gap of the sc lattice for the ZnO/polymer structures is narrower. However, the widths of the bcc and fcc lattices for the ZnO/polymer phononic crystals are much larger than those for the PZT-2/polymer structures. The lattice arrangements and the piezoelectricity have remarkable influences on the stop band behaviors.     

Fabrication of L10 FePtAg nanoparticles and a study of the effect of Ag during the annealing process

L1₀ ferromagnetic phase FePt nanoparticles containing Ag atoms (FePtAg) were synthesized by means of a liquid phase process, followed by annealing. The addition of Ag to FePt nanoparticles permits annealing to be conducted at a lower temperature (350 °C). This is further accompanied by a subsequent transformation in the crystal phase from the FCC superparamagnetic phase to the FCT (L1₀) ferromagnetic phase. The effects of annealing temperature and the Ag atoms inside the nanoparticles on the magnetic properties of the FePt nanoparticles have been studied. Using electron spectroscopy for the chemical analysis (ESCA), Ag atoms in the L1₀ phase FePtAg nanoparticles were found to be localized on the surface region of the annealed nanoparticles. The Ag atoms function to inhibit the oxidation of FePt, causing the particles to become more stable and to have ferromagnetic properties.     

Propagating mode in the photonic gap of 1D resonant Bragg reflector

Concerning “1D resonant photonic crystals”, i.e., 1D periodic arrays of resonant layers with a spacing satisfying the Bragg condition for resonant light, recent topics are summarized together with additional new findings. The central points are about (1) the recent theoretical finding of a new branch in the middle of photonic gap, (2) an approach-dependent controversy about its existence, (3) its consequence as sharp dips in reflectance spectrum and the corresponding internal field patters, indicating its propagating mode character, (4) the comparison between macroscopic and microscopic treatment of resonance effect, and (5) corrected transfer matrix method and its analytical equivalence with nonlocal response theory.     

Self-consistent solutions for single,intense beam polariton with linear polarization

New modes of propagation for a single, intense beam of light have been theoretically studied in the frequency region of giant two photon absorption (GTA) to excitonic molecule (EM) states. Self-consistent solutions for left and right circularly polarized (LCP and RCP respectively) components have been obtained for the polariton dispersion equations which include the ω- and k-dependent self-energy term for exciton due to the GTA process to EM. There are two types of solutions: [I] k(LCP) = k(RCP), [II] k(LCP) ≠ k(RCP). The induced branch for the former has a half of EM mass. There are experimental observations which support the existence of such new propagation modes.