New insight into the redox behavior of polyaniline

Polyaniline is one the most promising conducting polymers due to its ability to respond to environmental modifications by change in the properties. Here, we report an unprecedented redox behavior of polyaniline. Namely, propagation of reduction in thin highly organized polyaniline films immersed in acid aqueous medium (see Video 1). The films represent a homogeneous interpenetrating network of nano-sized polyaniline fibrils and water molecules. It is found that the presence of highly hydrated anions like HCOO^? favors both short- and long-range ordering, as well as the propagation of reduction in the polymer.     

Characterization of CdTe nanocrystals during their synthesis in liquid paraffin: optical properties and particle growth

This article presents a systematic investigation of the optical properties and the growth process of CdTe nanocrystals during their hot-injection-based synthesis in liquid paraffin. Cadmium(II) stearate and tributylphosphine telluride are used as precursors. The as-obtained nanocrystals are characterized by transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), UV–vis absorbance, and fluorescence spectroscopy. The changes in optical absorbance and fluorescence during the nanocrystal synthesis are studied. The average nanocrystal size and the mean nanocrystal concentration are derived from the optical spectra and their changes during the synthesis are investigated. It is found that synthesis at lower temperature (150 °C) favors the continuous nucleation and leads to the formation of relatively smaller nanocrystals (~3 nm in size), whereas the nanocrystal concentration is relatively constant during synthesis at higher temperature (250 °C) thus leading to the formation of larger nanocrystals (~5 nm in size).     

Survival and growth of Listeria monocytogenes on sausage formulated with inoculated and stored rework product

To assess the effect of including contaminated rework on survival and growth of Listeria monocytogenes, two sausage formulations (one American, Bologna sausage; and one Bulgarian, Stranja sausage) were inoculated with the pathogen and stored for 4 days at 10 °C plus 15 h at 30 °C. After storage, both rework types were included (at 20% and 40%) in corresponding fresh sausage emulsions and heated to 68, 70 and 71.7 °C; fresh Bologna and Stranja emulsions served as controls and were inoculated with 24 h broth cultures of the same 10-strain mixture of L. monocytogenes and thermally treated to the same temperatures. The results showed that heating to 68 and 70 °C inactivated 3–4 log CFU/g of the initial concentration of L. monocytogenes cells (>7 log CFU/g), while heat treatment to 71.7 °C in the center of experimental samples reduced counts by 6 log CFU/g. Survival of L. monocytogenes in samples heated to 68 and 70 °C was higher in controls. Control samples of Stranja emulsion heated to 71.7 °C allowed higher growth (P < 0.05) during storage (5 days at 10 °C) as compared to other control and experimental rework samples. The Stranja emulsion had a higher fat content (20.2%) compared to the Bologna emulsion (11%). This study provides evidence about the possible danger when potentially contaminated rework is stored and then introduced into fresh product formulations.     

A mathematical model for foreign body reactions in 2D

The foreign body reactions are commonly referred to the network of immune and inflammatory reactions of human or animals to foreign objects placed in tissues. They are basic biological processes, and are also highly relevant to bioengineering applications in implants, as fibrotic tissue formations surrounding medical implants have been found to substantially reduce the effectiveness of devices. Despite of intensive research on determining the mechanisms governing such complex responses, few mechanistic mathematical models have been developed to study such foreign body reactions. This study focuses on a kinetics-based predictive tool in order to analyze outcomes of multiple interactive complex reactions of various cells/proteins and biochemical processes and to understand transient behavior during the entire period (up to several months). A computational model in two spatial dimensions is constructed to investigate the time dynamics as well as spatial variation of foreign body reaction kinetics. The simulation results have been consistent with experimental data and the model can facilitate quantitative insights for study of foreign body reaction process in general.     

Note: An easy way to enable total internal reflection-fluorescence correlation spectroscopy (TIR-FCS) by combining commercial devices for FCS and TIR microscopy

Total internal reflection-fluorescence correlation spectroscopy (TIR-FCS) is a powerful method for studying dynamic processes at liquid-solid interfaces that may have numerous applications in biology, physics, and material science. Despite of its power and versatility, however, the use of TIR-FCS is still rather limited. The main reason for this is the need of a complex, in-house constructed optical setup whose assembly and adjustment is a quite difficult task. Clearly, the availability of ready to use, commercial TIR-FCS setups will strongly boost the application of this important method in many research areas. In this note we show that although such setups are still not available in the market, a proper combination of commercial devices for confocal fluorescence correlation spectroscopy and for total internal reflection microscopy may enable TIR-FCS in a way that do not require any special optical alignments. Furthermore, we demonstrate the capabilities of the setup by measuring the diffusion coefficient of single dye molecule and quantum dots in the very proximity of a water-glass interface.     

Finding Maximum Cliques on the D-Wave Quantum Annealer

This paper assesses the performance of the D-Wave 2X (DW) quantum annealer for finding a maximum clique in a graph, one of the most fundamental and important NP-hard problems. Because the size of the largest graphs DW can directly solve is quite small (usually around 45 vertices), we also consider decomposition algorithms intended for larger graphs and analyze their performance. For smaller graphs that fit DW, we provide formulations of the maximum clique problem as a quadratic unconstrained binary optimization (QUBO) problem, which is one of the two input types (together with the Ising model) acceptable by the machine, and compare several quantum implementations to current classical algorithms such as simulated annealing, Gurobi, and third-party clique finding heuristics. We further estimate the contributions of the quantum phase of the quantum annealer and the classical post-processing phase typically used to enhance each solution returned by DW. We demonstrate that on random graphs that fit DW, no quantum speedup can be observed compared with the classical algorithms. On the other hand, for instances specifically designed to fit well the DW qubit interconnection network, we observe substantial speed-ups in computing time over classical approaches.

     

Effect of ozone pre‐treatment of colored upland water on some biological parameters of sand filters

A pilot treatment plant for potable water, consisting of an ozonating unit followed by slow sand filters, was built in order to determine the relationship between filter biomass and performance following ozonation of colored feed water of upland origin. The color is due largely to the presence of humic substances, being most prevalent after heavy rainfall in the catchment. Ozone improves color by breaking down large humic molecules to smaller organic species, thus providing more bioavailable material in the water. Slow sand filtration, applied after ozonation, removes some of this material at the expense of more rapid clogging of the filters. This study on the schmutzdecke showed that the overall biomass of ozonated filters after clogging was significantly greater compared to non‐ozonated filters. Results revealed an increase in the heterotrophic biomass, but no significant change in the autotrophic community biomass, in slow sand filters receiving pre‐ozonated water.     

A qualitative examination of performance and energy yield of photovoltaic modules in southern Norway

Three different, commercially available photovoltaic modules have been monitored outdoors in the town of Grimstad, Norway. The present paper describes the experimental setup that was implemented, in particular details of the low-cost electronic loads. Results compare measured performance with manufacturer's data, and temperature measurements enable a comparison with performance at standard test condition temperature. Overall, the monocrystalline module performed best both regarding maximum efficiency and overall energy production, whereas the module based on triple junction amorphous silicon technology had the worst performance considering these criteria. The gross numbers of energy yield corresponding to measurements over a whole year show that photovoltaic technology could become a viable alternative also in a Northern country like Norway.