Liquid lens for adaptive interferometric particle imaging.

A liquid lens is used to realize an adaptive interferometric particle imaging system. The defocus parameter of the system can be changed instantaneously by adjusting the voltage applied to the lens. This enables adjusting the imaging conditions in real time. The setup is first tested on programmable rough particles generated by a digital micromirror device (DMD), and then with real glass particles under nanosecond pulse illumination.

Flexible ECG signal modeling and compression using alpha stable functions.

In this paper, we propose a flexible modeling technique for the ECG signals. Modeling is achieved by considering the weighted summation of elementary functions representing the waveforms that describe each component of the cardiac cycle. We thus evaluate the benefit brought by α-stable functions with respect to Gaussian functions in terms of modeling precision. Seven records from the MIT-BIH arrhythmia database have been used to assess the performances of the proposed modeling method, including Normal beat, Premature Ventricular Contraction beat, Right Bundle Block Branch beat and Paced beat. When applied on the chosen records, it turns out that α-stable modeling always outperforms Gaussian modeling. Since each waveform is related to a particular physiological event in the ECG cardiac cycle, we also exploit flexibility of choosing α-stable modeling instead of Gaussian one for some event of medical interest in order to solve compression purpose efficiency-quality compromise. The comparison of the α-stable model applied in compression with other techniques proves the efficiency of the proposed method, mainly in term of quality score.

Interferometric images of irregular rough particles in the presence of time-dependent index inhomogeneities in front of the imaging system.

A digital micromirrors device is used to reproduce the speckle-like interferometric images that would produce rough particles. Time-dependent index inhomogeneities induced by a flame are added between the particle and the imaging system. The size measurements deduced from 2D-Fourier analysis of the interferometric patterns show a less than 10% error when the programmed object is fixed, and a less than 20% error when a scintillation of the object is programmed.

Brillouin scattering-induced rogue waves in self-pulsing fiber lasers.

We report the experimental observation of extreme instabilities in a self-pulsing fiber laser under the influence of stimulated Brillouin scattering (SBS). Specifically, we observe temporally localized structures with high intensities that can be referred to as rogue events through their statistical behaviour with highly-skewed intensity distributions. The emergence of these SBS-induced rogue waves is attributed to the interplay between laser operation and resonant Stokes orders. As this behaviour is not accounted for by existing models, we also present numerical simulations showing that such instabilities can be observed in chaotic laser operation. This study opens up new possibilities towards harnessing extreme events in highly-dissipative systems through adapted laser cavity configurations.

Glasses formation, characterization, and crystal-structure determination in the Bi2O3-Sb2O3-TeO2 system prepared in an air.

A glass-forming domain is found and studied within Bi2O3-Sb2O3-TeO2 system. The glasses composition were obtained in pseudo-binary xSbO1.5, (1-x)TeO2 for 0.05 ≤ x ≤ 0.20. The constitution of glasses in the system Sb2O3-TeO2 was investigated by DSC, Raman, and Infrared spectroscopy. The influence of a gradual addition of the modifier oxides on the coordination geometry of tellurium atoms has been elucidated based Infrared and Raman studies and showed the transition of TeO4, TeO3+1, and TeO3 units with increasing Sb2O3 content. XRD results reveal the presence of three crystalline: γ-TeO2, α-TeO2, and SbTe3O8 phases during the crystallization process. The density of glasses has been measured. The investigation in the ternary system by the solid state reaction using XRD reveals the existence of a solid solution Bi1-x Sb1-x Te2x O4 isotopic to BiSbO4 with 0 ≤ x ≤ 0.1.

Decolorization of azo dyes with Enterobacter agglomerans immobilized in different supports by using fluidized bed bioreactor.

Immobilized cells of Enterobacter agglomerans, able to reduce azo dyes enzymatically, were used as a biocatalyst for the decolorization of synthetic medium containing the toxic azo dye methyl red (MR). This bacterial strain exhibits high ability to completely decolorize 100 mg/L of MR after only 6 h of incubation under aerobic conditions. Cells of E. agglomerans were immobilized in calcium alginate, polyacylamide, cooper beech, and vermiculite, and were used for the decolorization of MR from synthetic water by using a fluidized bed bioreactor. The highest specific decolorization rate was obtained when E. agglomerans was entrapped in calcium alginate beads and was of about 3.04 mg MR/g cell/h with a 50% conversion time ( t(1/2)) of about 1.6 h. Moreover, immobilized cells in calcium alginate continuously decolorized MR even after seven repeated experiments without significant loss of activity, while polyacrylamide-, cooper beech-, and vermiculite-immobilized cells retained only 62, 15, and 13% of their original activity, respectively.

Biosorption of mercury from aqueous solution by Ulva lactuca biomass.

The mercury biosorption onto non-living protonated biomass of Ulva lactuca, as an alternative method for mercury removal from aqueous solutions, was investigated. Batch equilibrium tests showed that at pH 3.5, 5.5 and 7 the maxima of mercury uptake values, according to Langmuir adsorption isotherm, were 27.24, 84.74 and 149.25 mg/g, respectively. The ability of Ulva lactuca biomass to adsorb mercury in fixed-bed column, was investigated as well. The influence of column bed height, flow rate and effluent initial concentration of metal was studied. The adsorbed metal ions were easily desorbed from the algal biomass with 0.3 N H(2)SO(4) solution. After acid desorption and regeneration with distilled water, the biomass could be reused for other biosorption assays with similar performances.

Purification and partial characterization of azoreductase from Enterobacter agglomerans.

Azoreductase, an enzyme catalyzing the reductive cleavage of the azo bond of methyl red (MR) and related dyes, was purified to electrophoretic homogeneity from Enterobacter agglomerans. This bacterial strain, isolated from dye-contaminated sludge, has a higher ability to grow, under aerobic conditions, on culture medium containing 100mg/L of MR. The enzyme was purified approximately 90-fold with 20% yield by ammonium sulfate precipitation, followed by three steps of column chromatography (gel-filtration, anion-exchange, and dye-affinity). The purified enzyme is a monomer with a molecular weight of 28,000 Da. The maximal azoreductase activity was observed at pH 7.0 and at 35 degrees C. This activity was NADH dependent. The K(m) values for both NADH and MR were 58.9 and 29.4 microM, respectively. The maximal velocity (V(max)) was 9.2 micromol of NADH min(-1)mg(-1). The purified enzyme is inhibited by several metal ions including Fe(2+) and Cd(2+).