Plasmonic split disk resonator based on graphene

In this paper, we designed and simulated an ultra-compact plasmonic filter consisting of a graphene ribbon laterally coupled to a graphene split disk resonator. Introducing a split inside the disk leads to split of the resonance modes symmetrically and asymmetrically. The spacing between the symmetric and asymmetric modes can be controlled through changing length of the split in the disk and the simulation results reveal that all modes identically shift as a result of changing the Fermi level of the disk. finite-difference time-domain method is used to investigate the device performance.     

Optical characterization of methanol compression-ignition combustion in a heavy-duty engine

In the search for renewable fuels, there are very few candidates as compelling as methanol. It can be derived from refuse material and industrial waste, while the infrastructure exists worldwide to support broad and fast adoption, potentially even as a “drop-in” fuel for existing vehicles with only minor modifications. The most efficient engines currently available are compression-ignition engines, however they often come with high emissions or compromises like the soot-NO_x trade-off. Methanol however, is a low sooting fuel that can potentially be used in such engines despite its high resistance to auto-ignition and reduce emissions while maintaining high engine efficiency. Due to the auto-ignition resistance, few studies of methanol compression-ignition exist and even fewer are conducted in an optically accessible engine. Here, two cases of premixed combustion and two of spray-driven combustion of methanol are studied in a Heavy-Duty optically accessible engine. Ignition and combustion propagation are characterized with a combination of time-resolved natural flame luminosity measurements and single-shot, acetone fuel-tracer, laser induced fluorescence. Additionally, Mie-scattering is used to identify the interaction between liquid spray and ignition sites in spray-driven methanol combustion. Results show that methanol combusts drastically different compared to conventional fuels, especially in spray-driven combustion. The evaporative cooling effect of methanol appears to play a major role in the auto-ignition characteristics of the delivered fuel. Ignition sites appear right at the end of injection when the evaporative cooling effect is withdrawn or at liquid length oscillations where, again the effect is momentarily retracted. To the authors’ knowledge, this has not been documented before.     

Cycle time and carrier life in immobilized-glucoamylase reactors

The activity of immobilized enzymes decays with time, and the capacity of a carrier will decrease with repeated regeneration. Relations between production cost and these factors are shown, and demonstrated with data on glucoamylase immobilized on porous glass. Optimum design calls for very low temperature and for cycle times several years long. A practical design may be made by limiting cycle time to an upper limit and calculating the temperature for which this time is optimum. In this case, reagents and carrier are the most important costs, even with an expensive enzyme.     

Analysis of cationic nutrients from foods by ion chromatography

This paper describes the feasibility of combining two relatively new technologies to generate data on the cationic nutrient content of foods. Single column ion chromatography was used to monitor several analytes following the use of a microwave digestion scheme aimed at rapid, multiple sample digestion. The result is a more streamline and productive approach to multi-sample preparation and multi-analyte determination when investigating the cation content of foods.

Linearity and limits of detection for the chromatographic procedure were established. Sample size as well as digestion acid type and amount were investigated during the microwave process. The method was applied to a variety of food matrices to evaluate its scope. Results generated with this method compare favorably to those from atomic absorption.

Finally, capillary ion electrophoresis (Waters' trade name: Capillary Ion Analysis), a subset of capillary electrophoresis which has been optimized for ion analysis, was applied to the sample digest to investigate the usefulness of this technology to the analysis of mono-/divalent cations from foods.     

Application of fixed-nuclei scattering theory to electron methane elastic and inelastic differential cross sections at 10 eV impact energy

Quantum mechanical calculations are reported for electron-methane elastic scattering and rotational excitation cross sections at 10 eV impact energy. The calculations employ a fixed-nuclei close coupling formalism with full incorporation of symmetry and are used to test previous laboratory-frame calculations employing a direct coupling approximation. Good agreement is obtained. Additional comparisons to previous theoretical and experimental work are also presented, and the contributions of the various symmetries to the cross sections are analyzed in terms of representatve matrix elements of the interaction potential.     

On the nonexistence of strictly diabatic molecular electronic bases

In a recent publication (M. Baer, A. Alijah, Chem. Phys. Lett. 319 (2000) 489), it is proposed that, contrary to a number of statements in the literature, it may indeed be possible to construct strictly diabatic electronic basis sets in molecular systems. We show that the result of Baer and Alijah is invalid.