Long-range surface plasmon polaritons propagating on a dielectric waveguide support

In the traditional long-range surface plasmon geometry, an ultrathin metal film is sandwiched between two layers having identical dielectric constants. Here we demonstrate the long-range surface plasmon polariton (LRSPP) properties for a new structure where a thin layer with a dielectric constant exceeding that of the surroundings is inserted within the sandwich, provided the layer thickness d satisfies the condition k(⊥)d=mπ where k(⊥) is the component of the guide wavevector perpendicular to the layer and m is an integer. The resulting plasmon modes have smaller losses and nearly the same phase velocity as the original LRSPP. This provides a strategy to support silver films having thicknesses of 10's of nanometers to create plasmonic devices for sensor applications.     

Lu2SiO5:Ce透明薄膜改性及其发光性能

Lu2SiO5:Ce具有高密度、高光产额、快衰减等优点,是一种性能优异的新型X射线闪烁薄膜材料.本文采用溶胶-凝胶工艺和旋涂技术,以无机盐为原料、2-甲氧基乙醇为溶剂、聚乙二醇(PEG)为改性剂,在石英基片上成功制备出Lu2SiO5:Ce透明薄膜,较为详细地研究了PEG对该薄膜发光性能的影响.结果表明当采用浓度为12....     

The Kramer Sampling Theorem Revisited

The classical Kramer sampling theorem provides a method for obtaining orthogonal sampling formulas. Besides, it has been the cornerstone for a significant mathematical literature on the topic of sampling theorems associated with differential and difference problems. In this work we provide, in an unified way, new and old generalizations of this result corresponding to various different settings; all these generalizations are illustrated with examples. All the different situations along the paper share a basic approach: the functions to be sampled are obtaining by duality in a separable Hilbert space \(\mathcal {H}\) through an \(\mathcal {H}\) -valued kernel K defined on an appropriate domain.     

Area integral functions for sectorial operators on L spaces

Area integral functions are introduced for sectorial operators on L^p-spaces. We establish the equivalence between the square and area integral functions for sectorial operators on L^p spaces. This follows that the results of Cowling, Doust, McIntosh, Yagi, and Le Merdy on H^infin functional calculus of sectorial operators on L^p-spaces hold true when the square functions are replaced by the area integral functions.     

A spectral theory approach for extreme value analysis in a tandem of fluid queues

We consider a model to evaluate performance of streaming media over an unreliable network. Our model consists of a tandem of two fluid queues. The first fluid queue is a Markov modulated fluid queue that models the network congestion, and the second queue represents the play-out buffer. For this model the distribution of the total amount of fluid in the congestion and play-out buffer corresponds to the distribution of the maximum attained level of the first buffer. We show that, under proper scaling and when we let time go to infinity, the distribution of the total amount of fluid converges to a Gumbel extreme value distribution. From this result, we derive a simple closed-form expression for the initial play-out buffer level that provides a probabilistic guarantee for undisturbed play-out.     

Algebras Whose Coxeter Polynomials are Products of Cyclotomic Polynomials

Let A be a finite dimensional algebra over an algebraically closed field k. Assume A is basic connected with n pairwise non-isomorphic simple modules. We consider the Coxeter transformation ? _A as the automorphism of the Grothendieck group K ₀(A) induced by the Auslander-Reiten translation τ in the derived category Der(modA) of the module category modA of finite dimensional left A-modules. We say that A is an algebra of cyclotomic type if the characteristic polynomial χ _A of ? _A is a product of cyclotomic polynomials. There are many examples of algebras of cyclotomic type in the representaton theory literature: hereditary algebras of Dynkin and extended Dynkin types, canonical algebras, some supercanonical and extended canonical algebras. Among other results, we show that: (a) algebras satisfying the fractional Calabi-Yau property have periodic Coxeter transformation and are, therefore, of cyclotomic type, and (b) algebras whose homological form h _A is non-negative are of cyclotomic type. For an algebra A of cyclotomic type we describe the shape of the Auslander-Reiten components of Der(modA).     

Multiresidue analysis of quinolones in water by ultra‐high perfomance liquid chromatography with tandem mass spectrometry using a simple and effective sample treatment

A rapid and simple analytical method has been developed for the determination of 19 quinolones in environmental water samples using ultra high performance liquid chromatography with tandem mass spectrometry. Chromatographic and detection conditions have been optimized and the separation was achieved in less than 4 min. The separation was carried out using a new‐generation column filled with superficially porous particles, resulting in lower backpressure and better resolution than totally porous particle columns. The quinolones were detected by electrospray ionization in positive mode using multiple‐reaction monitoring mode for acquisition. A sample treatment based on liquid–liquid extraction and phase separation via salting‐out was employed to achieve a fast and simple extraction that enables the multiresidue analysis. The method has been validated for an environmental well water sample from a mountain area. Very low limits of detection (between 10 and 90 ng/L) with relative standard deviations lower than 16.5% and recoveries higher than 73% were achieved. Moreover, well waters from different origins (mountain and coast areas and irrigated land) have been evaluated and similar results were obtained.     

Bis(1,10‐phenanthroline)(thio­sulfato)­manganese(II) methanol solvate and catena‐poly­[[di­aqua(2,9‐di­methyl‐1,10‐phenanthroline)­manganese(II)]‐μ‐thio­sulfato]

The structure of bis(1,10‐phenanthroline‐κ²N,N′)(thio­sulfato‐κ²O:S)­manganese(II) methanol solvate, [Mn(S₂O₃)(C₁₂H₈N₂)₂]·CH₃OH, is made up of Mn²⁺ centers coordinated to two bidentate phenanthroline (phen) groups and an S,O‐chelating thio­sulfate anion, forming monomeric entities. The structure of catena‐poly­[[di­aqua(2,9‐di­methyl‐1,10‐phen­anthro­line‐κ²N,N′)­manganese(II)]‐μ‐thio­sulfato‐κ²O:S], [Mn(S₂O₃)(C₁₄H₁₂N₂)(H₂O)₂]_n, is polymeric, consisting of Mn(dmph)(H₂O)₂ units (dmph is 2,9‐di­methyl‐1,10‐phenanthroline) linked by thio­sulfate anions acting in an S,O‐chelating manner.     

GaAsN/AlAs/AlGaAs double barrier quantum wells grown by molecular beam epitaxy as an alternative to infrared absorption below 4 μm

In this work, we report on the design, growth and characterization of GaAsN/AlAs/AlGaAs double barrier quantum well infrared detectors to achieve intraband absorption below 4 μm. Due to the high effective mass of N-dilute alloys, it is common for these N-containing double barrier quantum well structures to have more than one bound state within the quantum well, enabling the possibility of achieving multispectral absorption from these confined levels to the quasi-bound. Based on a transfer matrix calculation we will study the influence of the potential parameters, in particular the well width and the introduction of a GaAs spacer layer in between the N-well and the AlAs barriers. We will compare the case in which there are two confined levels with the case in which only one level is bound, like in the conventional AlGaAs/AlAs/GaAs structures. On the basis of the simulation, we have grown and characterized some N-containing double barrier detectors. Moreover, an optimization of the post-growth annealing treatments of the GaAsN quantum well structures has also been performed. Finally, room temperature absorption measurements of both as-grown and annealed samples are presented and analyzed.