Sampling free and particle‐bound chemicals using solid‐phase microextraction and needle trap device simultaneously

The possibility of sampling the free and particle‐bound concentrations of organic compounds was studied using two different sampling techniques at the same time: needle trap device (NTD) and solid‐phase microextraction (SPME). In this study, a mosquito coil was used to produce gaseous (free) and particle‐bound compounds. Allethrin, the active ingredient in mosquito coils, was chosen as the target analyte. Under the same sampling conditions, the amount of allethrin extracted from the mosquito‐coil smoke was higher for the NTD compared to the SPME fiber, while the extracted amounts were almost the same for both devices when sampling gaseous samples of allethrin. These results can be explained by the fact that the SPME fiber can only extract free molecules (based on diffusion), whereas the NTD, an exhaustive sampling device, collects both free and particle‐bound allethrin. Breakthrough for NTD and carryover for both NTD and SPME were negligible under the given sampling and desorption conditions.     

On a fixed point theorem in 2-Banach spaces and some of its applications

The aim of this article is to prove a fixed point theorem in 2-Banach spaces and show its applications to the Ulam stability of functional equations. The obtained stability results concern both some single variable equations and the most important functional equation in several variables, namely, the Cauchy equation. Moreover, a few corollaries corresponding to some known hyperstability outcomes are presented.     

Fixed-point theorem in classes of function with values in a dq-metric space

We prove a fixed point result for nonlinear operators, acting on some classes of functions with values in a dq-metric space, and show some applications of it. The result has been motivated by some issues arising in Ulam stability. We use a restricted form of a contraction condition.     

Magnetic shape anisotropy calculations of Fe nanostructures at the Si/Fe(1 1 1) interface

The influence of Si capping layers on the magnetic properties of thin Fe films grown on Si(1 1 1) has been studied by means of shape anisotropy calculations. Fe surface morphology simulations are realized using experimental STM data. Surface modifications induced by the interaction between the Si overlayer and the Fe surface are performed in agreement with the model proposed in a previous work by Stephan et al. [J. Magn. Mater. 293 (2005) 746]. Calculations of the uniaxial anisotropy energy constant K_u are then performed on the modified Fe surface morphology for different Si deposition geometries as proposed in the model. The relevant data deduced by this method such as anisotropy constants and their related easy axis direction, are directly compared to the experimental ones obtained by ex situ magneto-optical Kerr effect (MOKE) measurements at room temperature using the transverse bias initial inverse susceptibility and torque (TBIIST) method. We show that a very good agreement between those results leads to a confirmation of the proposed model.     

Boron doped carbon nanotubes via ceramic catalysts

A facile metal catalyst free route to synthesize boron doped (0.6%–1.0%) carbon nanotubes via ceramic nanowires in which the formation of the nanowires (probably serving as templates), the carbon nanotubes and their doping all occur unanimously in the reaction, is presented.

     

8,11-Dioxa-(3,4-benzo)-(4.3.3)propellan

The synthesis of the title compound derived from the tetralin system is reported. On the basis of PMR and MS spectra the possibility of the formation of an isomeric bispirane is discussed.

     

Dendrites and light mappings

It is shown that a metric continuum is a dendrite if and only if for every compact space (continuum) and for every light confluent mapping such that there is a copy of in for which the restriction is a homeomorphism. As a corollary it follows that only dendrites have the lifting property with respect to light confluent mappings. Other classes of mappings are also discussed. This is a continuation of a previous study by the authors (2000), where open mappings were considered.

     

Uncountable intersections of open sets under CPA

We prove that the Covering Property Axiom CPA , which holds in the iterated perfect set model, implies the following facts.

• If is an intersection of -many open sets of a Polish space and has cardinality continuum, then contains a perfect set.

• There exists a subset of the Cantor set which is an intersection of -many open sets but is not a union of -many closed sets.

The example from the second fact refutes a conjecture of Brendle, Larson, and Todorcevic.