Electrodeless direct current dielectrophoresis using reconfigurable field-shaping oil barriers

We demonstrate dielectrophoretic (DEP) potential wells using pairs of insulating oil menisci to shape the DC electric field. These oil menisci are arranged in a configuration similar to the quadrupolar electrodes, typically used in DEP, and are shown to produce similar field gradients. While the one-pair well produces a focusing effect on particles in flow, the two-pair well results in creating spatial traps against crossflows. Uncharged polystyrene particles were used to map the DEP force fields and the experimental observations were compared against the field profiles obtained by numerically solving Maxwell's equations. We demonstrate trapping of a single particle due to negative DEP against a pressure-driven crossflow. This can be easily extended to trap and hold cells and other objects against flow for a longer time. We also show the results of particle trapping experiments performed to observe the effect of adjusting the oil menisci and the gap between two pairs of menisci in a four-menisci configuration on the nature of the DEP well formed at the center. A design parameter, Theta, capturing the dimensions of the DEP energy well, is defined and simulations exploring the effects of different geometric features on Theta are presented.     

Fluorescent Molecular Logic Gates Driven by Temperature and by Protons in Solution and on Solid

Temperature-driven fluorescent NOT logic is demonstrated by exploiting predissociation in a 1,3,5-trisubstituted Δ²-pyrazoline on its own and when grafted onto silica microparticles. Related Δ²-pyrazolines become proton-driven YES and NOT logic gates on the basis of fluorescent photoinduced electron transfer (PET) switches. Additional PASS 1 and YES+PASS 1 logic gates on silica are also demonstrated within the same family. Beside these small-molecule systems, a polymeric molecular thermometer based on a benzofurazan-derivatized N-isopropylacrylamide copolymer is attached to silica to produce temperature-driven fluorescent YES logic.     

Inverse Optimal Control Via Diagonal Stabilization Applied to Attitude Tracking of a Reusable Launch Vehicle

Journal of Optimization Theory and Applications - In this work, a novel strategy for the inverse optimal control of a class of affine nonlinear systems is proposed. The proposed strategy involves...     

Communicating chemical congregation: a molecular AND logic gate with three chemical inputs as a "lab-on-a-molecule" prototype

We demonstrate the first three-input molecular AND logic gate based on three chemical inputs as a direct way of detecting congregations of chemical species. The AND gate operates in water and responds to Na+, H+, and Zn2+ inputs with an enhanced fluorescence signal when pre-set concentration thresholds are exceeded. Future "lab-on-a-molecule" devices could have application in medicine for rapid disease screening.     

Identification of Cellulase Gene from the Metagenome of Equus burchelli Fecal Samples and Functional Characterization of a Novel Bifunctional Cellulolytic Enzyme

The metagenomic approach has been used successfully to isolate novel biocatalyst gene from uncultured microorganisms. The gene encoding exo-1,4-??-glucanase avicelase was amplified from the metagenome of the Equus burchelli fecal sample and cloned. The gene was found to be of 1,007?bp of nucleotide which encodes a protein of 318 amino acids with a calculated MW of 36?kDa. The deduced amino acid sequence was homologous with cellulases belonging to the glycosyl hydrolases 6 superfamily. The expressed protein was active towards the substrates avicel and carboxymethyl cellulose, indicating that it has bifunctional cellulolytic enzyme activity. The recombinant protein showed an activity of 5.23?U with specific activity of 6.8?U?mg^?1 protein with the substrate avicel, while when CMC was used, an activity of 3.0?U with a specific activity of 4.2?U?mg^?1 protein was achieved. Its optimum pH was determined to be 7.0 and optimum temperature of 35°C.     

Layered double hydroxides as potential chromate scavengers

The LDH of Ni with Fe, having the formula Ni(1-x)Fe(x)(OH)2(A(n-))(x/n)yH2O (A = NO3-, Cl-; x = 0.25, 0.33), scavenges CrO4(2-) ions from solution throughout the concentration range examined (0.00625-0.25 N). The CrO4(2-) uptake capacity is independent of the anion in the starting LDH but is higher when x = 0.25 (3.60 meq g(-1)) as compared to x = 0.33 (2.40 meq g(-1)). These values are higher than those observed for control compounds beta-Ni(OH)2 (1.86 meq g(-1)) and FeO(OH) (1.26 meq g(-1)), which do not have any interlayer chemistry, showing that chromate uptake takes place by its incorporation in the interlayer region by a stoichiometric anion-exchange reaction, rather than by adsorption. Nevertheless, the interaction between the LDH and the chromate ions is weak. The weak interaction is due to the mismatch between the symmetry of the chromate ions and the symmetry of the interlayer site, which introduces turbostratic disorder in the chromate-intercalated LDHs. The chromate ions can be completely leached out by soaking the LDH in a sodium carbonate solution.     

Optimally stabilized beam pairs

In this paper, evolution of two co-axially co-propagating beams with the propagation distance in a Kerr type nonlinear medium has been analyzed for all possible physical parameters and situations. For the first time, the paper analyzes useful “optimally stabilized” (minimum width oscillations of beams with distance of propagation) pairing of bright-bright, bright-dark, dark-dark beams of same/different wavelengths and of same/different widths using coupled nonlinear Schrödinger equation (NLSE) that has been solved using split-step Fourier method. Soliton pairs of two unequal beam widths are known to be impossible, however, it is shown that “optimally stabilized” pairing is possible in such cases. Existence surfaces for optimally stabilized pairing have also been revealed for different interaction coefficient of the coupled beams.