柑桔黄龙病的可见-近红外光谱特征

柑桔黄龙病是一种以木虱为载体的细菌病原,目前还没有行之有效的治疗方法,对世界柑桔产业构成了严重的威胁。探索快速检测柑桔黄龙病的方法,对该病的诊断、评估及进一步的控制都具有重要意义。该研究采用了快速、无损的光谱方法对该病害特征进行初步探索。实验针对健康及染病植株的叶片及冠层,分别在实验室条件及田间环境下测量了其可见-近红外光谱反射率,以分析寻找二者的光谱差异。对原始光谱数据进行了平滑、聚类平均等预处理,并求取了一阶微分以确定其红边位置(red edge position, REP)。为了应对一阶微分在REP处的多个波峰现象,采用了线性外插值法及拉格朗日插值法量化REP。研究结果显示,健康及染病样本的反射率在可见光、近红外具有明显的差异。相比于健康样本,染病样本因其呈现的黄化现象,使其反射率在可见光区较高;又因黄龙病菌会明显阻碍叶片对水分的吸收而使其反射率在近红外较低。REP同样显示了潜在的区分能力,其明显随着染病程度的加深逐渐向红波段移动。在染病程度差异较大的数据集中,REP平均值相差达20 nm;而在染病程度差异较小的数据集中,阈值分割法的分类精度也高达90%以上,且线性外插值法的分类精度略高于拉格朗日插值法。本研究成果为利用光谱技术快速无损检测柑桔黄龙病提供了可靠的理论依据。     

Structural and magnetic properties of Fe doped NiO

Mott-Hubbard anti-ferromagnetic insulator, NiO shows p-type semiconducting behaviour due to vacancy at Ni²⁺ site in its bunsenite structure. We report the modification of structural and magnetic order in NiO on Fe doping. NiO samples at different Fe concentrations in the range 0 to 5 at.% have been prepared by chemical co-precipitation and post thermal decomposition method. Both structural and magnetic characterization reveal that with increasing Fe doping concentration, NiO evolves as a magnetically inhomogeneous state out of the parent homogeneous antiferromagnetic state. In addition, structural inhomogeneity was also observed with Fe precipitating to γ-Fe₂O₃ phase, the signature of which could be clearly seen for Fe content beyond 2 at.%. At lower Fe content however, some amount of Fe occupies lattice and interstitial sites in the NiO matrix and drive the latter to acquire ferromagnetic ordering, which was evident from a clear hysteresis loop at 300 K.      

Effect of cobalt substitution on microstructure and magnetic properties in ZnO nanoparticles

Ferromagentic semiconductors have been actively pursued because of their potential as spin polarized carrier sources and easy integration into semiconductor technology. One such material, ZnO has been shown to be a potential Diluted Magnetic Semiconductor (DMS). The appearance of ferromagnetism, however, is found to be sensitive to the processing conditions. We report synthesis of ZnO nanoparticles of size ∼20 nm by a simple co-precipitation technique using metal nitrates and NaOH as precipitant. The particles are self-organised and reveal single crystalline behaviour in electron diffraction pattern. Incorporation of Co in ZnO matrix leads not only to the reduction in crystallite size but also to the modification of the structure. At 5% Co, the particles are highly textured. The particles also aggregate and the aggregated mass have nearly rectangular shape as seen through TEM. Increasing Co to 10%, results into further reduction of particle size and the particles self organize in a line, which looks like nanofibers. This alignment of particles increases by increasing the Co content further. This type of growth of nanofibers above Co ≥ 10% is well correlated with the anisotropic peak broadening observed in the XRD spectra. In addition, Co substitute Zn site up to 20% without showing any extra phase in XRD spectra as compared to 7 to 10% in case of bulk. Transport and magnetic studies indicate that conductivity increases with increasing Co content, but carrier mediated ferromagnetism is absent down to 10 K.      

Evolution of surface morphology of NiO thin films under swift heavy ion irradiation

NiO nanoparticle thin films grown on Si substrates were irradiated by 107 MeV Ag⁸⁺ ions. The films were characterized by glancing angle X-ray diffraction and atomic force microscopy. Ag ion irradiation was found to influence the shape and size of the nanoparticles. The pristine NiO film consisted of uniform size (∼100 nm along major axis and ∼55 nm along minor axis) elliptical particles, which changed to also of uniform size (∼63 nm) circular shape particles on irradiation at a fluence of 3 × 10¹³ ions cm⁻². Comparison of XRD line width analysis and AFM data revealed that the particles in the pristine films are single crystalline, which turn to polycrystalline on irradiation with 107 MeV Ag ions.     

Solution of Schrodinger Equation for Two-Dimensional Complex Ouartic Potentials

We investigate the quasi-exact solutions of the Schrodinger wave equation for two-dimensional non-hermitian complex Hamiltonian systems within the frame work of an extended complex phase space characterized by x = x1 ＋ ip3, y = x2 ＋ ip4, px= p1＋ ix3, py= p2 ＋ ix4. Explicit expressions of the energy eigenvalues and the eigenfunctions for ground and first excited states for a complex quartic potential are obtained. Eigenvalue spectra of some variants of the complex quartic potential, including PT-symmetrie one, are also worked out.     

Relaxation studies of spray deposited Bi2Co0.1V0.9O5.35 solid electrolyte thin films on stainless steel substrate

The room temperature-stabilized γ-phase ion conducting Bi₂Co_0.1V_0.9O_5.35 thin film was deposited by spray pyrolysis on stainless steel substrate. The intra-grain and grain interior charge transfer was confirmed in these films with impedance spectroscopic measurements done from 1 Hz to 10 MHz in the temperature range 550 K to 741 K. Impedance data further revealed non-Debye kind of relaxation dispersion in the film. The relaxation frequency ranges from 10 to 100 Hz, which predicts long range jumping of the oxygen ions with chemical diffusivity. The Arrhenius plots for relaxation frequency and grain boundary conductivity were found to have same activation energy revealing grain boundary dominant conduction. The effect of polycrystallinity on relaxation dispersion is investigated for the first time on Bi₂Co_0.1V_0.9O_5.35 thin films using impedance formalism.     

Synthesis and property study of UV-curable hyperbranched polyurethane acrylate/ZnO hybrid coatings

In the present work, the third generation hyperbranched polyester (HBPE-3G) based polyurethane acrylate (HBPUA-32)/ZnO hybrid coatings are prepared, by modifying 16 hydroxyl groups of HBPE-3G with an acrylic adduct. The HBPE-32 is prepared from the di-trimethylol propane and 2,2-bis(hydroxymethyl) propionic acid, converted into hybrid coatings by incorporating 1%, 3% and 5% nano ZnO powder into the polymer matrix. The ¹H, ¹³C NMR and FT-IR spectroscopy methods are used for structural characterization, degree of branching calculation and structure to property correlation study and various hybrid film properties are analyzed by TGA, DMTA, XRD and SEM instruments.     

Symmetric duality for minimax mixed integer programming problems with pseudo-invexity

In this paper, we consider the pair of symmetric dual multiobjective variational mixed integer programs proposed by Chen and Yang [X. Chen, J. Yang, Symmetric duality for minimax multiobjective variational mixed integer programming problems with partial-invexity, European Journal of Operational Research 181 (2007) 76-85.] and extend some of their results under the assumptions of partial-pseudo-invexity and separability on the functions involved. These results include several results available in literature as special cases.     

Sensitivity analysis for a system of parametric general quasi-variational-like inequality problems in uniformly smooth Banach spaces

In this paper, using the concept of P-η-proximal-point mapping introduced by Kazmi and Bhat [11], we study the existence and sensitivity analysis of the solution set of a system of parametric general quasi-variational-like inequality problems in uniformly smooth Banach spaces. Further under suitable conditions, we discuss the Lipschitz continuity of the solution set with respect to the parameters. The approach used in this paper may be treated as an extension and unification of approaches for studying sensitivity analysis for various important classes of variational inequalities given in [1,2,4,12,14–16,21–24].     

On nonlinear multiple objective fractional programming involving semilocally type-I univex functions

The aim of this paper is to obtain sufficient optimality conditions for a nonlinear multiple objective fractional programming problem involving semilocally type-I univex and related functions. Furthermore, a general dual is formulated and duality results are proved under the assumptions of generalized semilocally type-I univex and related functions. Our results generalize several known results in the literature.