Rapid Method to Screen Unopened Bottles to Detect Concealed Drugs

A bottle screening method to detect smuggling drugs was developed based on a series of rapid and automated magnetic resonance measurements. Liquid alteration is detected by evaluating chemical and physical properties of the liquid, scanning the bottle with a compact, non-contact magnetic resonance probe. Chemical and molecular diffusion changes are detected by means of the magnetic resonance relaxation time. The inspection device automatically detects the presence of concealed powders dissolved in liquids in a second timescale. The non-ionizing, non-contact method effectively screens bottles, regardless of their shape, size, and color. The proposed system configuration does not require a large magnet generating uniform magnetic fields; rather it inspects the liquid using a compact probe positioned on the wall of the bottle. For a variety of samples tested, the screening does not require detailed information on the expected content of the bottle.     

XANES speciation of mercury in three mining districts – Almadén,Asturias (Spain), Idria (Slovenia)

The mobility, bioavailability and toxicity of mercury in the environment strongly depend on the chemical species in which it is present in soil, sediments, water or air. In mining districts, differences in mobility and bioavailability of mercury mainly arise from the different type of mineralization and ore processing. In this work, synchrotron‐based X‐ray absorption near‐edge spectroscopy (XANES) has been taken advantage of to study the speciation of mercury in geological samples from three of the largest European mercury mining districts: Almadén (Spain), Idria (Slovenia) and Asturias (Spain). XANES has been complemented with a single extraction protocol for the determination of Hg mobility. Ore, calcines, dump material, soil, sediment and suspended particles from the three sites have been considered in the study. In the three sites, rather insoluble sulfide compounds (cinnabar and metacinnabar) were found to predominate. Minor amounts of more soluble mercury compounds (chlorides and sulfates) were also identified in some samples. Single extraction procedures have put forward a strong dependence of the mobility with the concentration of chlorides and sulfates. Differences in efficiency of roasting furnaces from the three sites have been found.     

Non‐intrusive reduced‐order modeling for multiphase porous media flows using Smolyak sparse grids

In this article, we describe a non‐intrusive reduction method for porous media multiphase flows using Smolyak sparse grids. This is the first attempt at applying such an non‐intrusive reduced‐order modelling (NIROM) based on Smolyak sparse grids to porous media multiphase flows. The advantage of this NIROM for porous media multiphase flows resides in that its non‐intrusiveness, which means it does not require modifications to the source code of full model. Another novelty is that it uses Smolyak sparse grids to construct a set of hypersurfaces representing the reduced‐porous media multiphase problem. This NIROM is implemented under the framework of an unstructured mesh control volume finite element multiphase model. Numerical examples show that the NIROM accuracy relative to the high‐fidelity model is maintained, whilst the computational cost is reduced by several orders of magnitude. Copyright © 2016 John Wiley & Sons, Ltd.     

Water flows induced by microwave electric fields in microsystems

AC electric fields are of increasing importance for the generation of fluid flows in microsystems. We analyse numerically the use of AC electric fields at microwave frequencies for electro-thermal actuation of water in microdevices. Water is heated because of its significant dielectric loss at microwave frequencies. Buoyancy and dielectric forces actuate in the liquid bulk, and the relative importance between them is studied. The microwave liquid actuation can be used for pure water as well as for water saline solutions, such as bio-fluids. Therefore, it is of interest for the Lab-on-a-Chip technology.     

Vertical Electronic Spectra of the Isovalent Molecules H2CNH,H2SiNH,H2CPH and H2SiPH on the Basis of MRD-CI Calculations

Abstract

Large-scale multi-reference single and double-excitation configuration interaction (MRD-CI) calculations are employed for the study of the isovalent compounds H₂CNH, HLSiNH, hLCPH and H₂SiPH in their ground state equilibrium geometry. The dipole moments and charge distributions are given. The vertical excitation energies to the intravalence states ^3,1 (n, π*) and ^3,1(π,π*) and to the first members of the Rydberg series originating from n and - MO's respectively are predicted; the first two ionization potentials and the Rydberg term values are also calculated. In H₂CNH, mixing of Rydberg and valence-shell states with CN stretching is analyzed. The trends in relative stability of electronic and ionized states can be directly related to increased orbital stability of n relative to π as soon as a first-row constituent is replaced by a second-row atom. The calculations explain the diffuse character of the uv spectrum of imines; they treat the molecules H₂SiNH and H₂SiPH for the first time and present a large number of data for all four molecules which can serve as a basis for future experimental investigations on these and related compounds.     

On the Addition of Aryl Radicals to Graphene: The Importance of Nonbonded Interactions

Dispersion‐corrected density functional theory is utilized to study the addition of aryl radicals to perfect and defective graphene. Although the perfect sheet shows a low reactivity against aryl diazonium salts, the agglomeration of these groups and the addition onto defect sites improves the feasibility of the reaction by increasing binding energies per aryl group up to 27 kcal mol^?1. It is found that if a single phenyl radical interacts with graphene, the covalent and noncovalent additions have similar binding energies, but in the particular case of the nitrophenyl group, the adsorption is stronger than the chemisorption. The single vacancy shows the largest reactivity, increasing the binding energy per aryl group by about 80 kcal mol^?1. The zigzag edge ranks second, enhancing the reactivity 5.4 times with respect to the perfect sheet. The less reactive defect site is the Stone–Wales type, but even in this case the addition of an isolated aryl radical is exergonic. The arylation process is favored if the groups are attached nearby and on different sublattices. This is particularly true for the ortho and para positions. However, the enhancement of the binding energies decreases quickly if the distance between the two aryl radicals is increased, thereby making the addition on the perfect sheet difficult. A bandgap of 1–2 eV can be opened on functionalization of the graphene sheets with aryl radicals, but for certain configurations the sheet can maintain its semimetallic character even if there is one aryl radical per eight carbon atoms. At the highest level of functionalization achieved, that is, one aryl group per five carbon atoms, the bandgap is 1.9 eV. Regarding the effect of using aryl groups with different substituents, it is found that they all induce the same bandgap and thus the presence of NO₂, H, or Br is not relevant for the alteration of the electronic properties. Finally, it is observed that the presence of tetrafluoroborate can induce metallic character in graphene.     

Synthesis and Spectroscopic Characterization of Fluorophore‐Labeled Oligospiroketal Rods

Fluorescence probes consisting of well‐established fluorophores in combination with rigid molecular rods based on spirane‐type structures were investigated with respect to their fluorescence properties under different solvent conditions. The attachment of the dyes was accomplished by 1,3‐dipolar cycloaddition between alkynes and azides (‘click’ reaction) and is a prime example for a novel class of sensor constructs. Especially, the attachment of two (different) fluorophores on opposite sides of the molecular rods paves the way to new sensor systems with less bulky (compared to the conventional DNA‐ or protein‐based concepts), nevertheless rigid spacer constructs, e.g., for FRET‐based sensing applications. A detailed photophysical characterization was performed in MeOH (and in basic H₂O/MeOH mixtures) for i) rod constructs containing carboxyfluorescein, ii) rod constructs containing carboxyrhodamine, iii) rod constructs containing both carboxyfluorescein and carboxyrhodamine, and iv) rod constructs containing both pyrene and perylene parts. For each dye (pair), two rod lengths with different numbers of spirane units were synthesized and investigated. The rod constructs were characterized in ensemble as well as single‐molecule fluorescence experiments with respect to i) specific rod? dye and ii) dye? dye interactions. In addition to MeOH and MeOH/NaOH, the rod constructs were also investigated in micellar systems, which were chosen as a simplified model for membranes.     

Copper-containing dendromesogens: the influence of the metal on the mesomorphism

The synthesis and liquid crystalline behaviour of the first and second generations of a dendrimeric structure based on poly(propyleneimine)(DAB-dendr(NH₂)_x) are reported. 4-(4-n-Alkoxybenzoyloxy)salicylaldehydes are used as mesogenic moieties attached at the peripheral amino groups of the dendrimers giving rise to dendromesogens with four and eight mesogenic branches. From these dendromesogens, considered as organic ligands, were prepared six metal-containing dendrimers which incorporate two or four copper atoms in their structures. All the dendrimeric ligands and three of the metal-containing dendrimers exhibit liquid crystalline properties which were studied by optical microscopy, DSC, X-ray diffraction and EPR spectroscopy.