Stride-to-stride energy regulation for robust self-stability of a torque-actuated dissipative spring-mass hopper

In this paper, we analyze the self-stability properties of planar running with a dissipative spring-mass model driven by torque actuation at the hip. We first show that a two-dimensional, approximate analytic return map for uncontrolled locomotion with this system under a fixed touchdown leg angle policy and an open-loop ramp torque profile exhibits only marginal self-stability that does not always persist for the exact system. We then propose a per-stride feedback strategy for the hip torque that explicitly compensates for damping losses, reducing the return map to a single dimension and substantially improving the robust stability of fixed points. Subsequent presentation of simulation evidence establishes that the predictions of this approximate model are consistent with the behavior of the exact plant model. We illustrate the relevance and utility of our model both through the qualitative correspondence of its predictions to biological data as well as its use in the design of a task-level running controller.     

Stereoselective Synthesis of 1,2,3‐Triazolooxazine and Fused 1,2,3‐Triazolo‐δ‐Lactone Derivatives

The stereoselective synthesis of 1,2,3‐triazolooxazine and fused 1,2,3‐triazolo‐δ‐lactone by applying chemoenzymatic methods is described. trans‐2‐Azidocyclohexanol was successfully resolved by Novozyme 435 with an ee value of 99%. Installation of the alkyne moiety on the enantiomerically enriched azidoalcohol by O‐alkylation, followed by intramolecular azide? alkyne [3+2] cycloaddition resulted in the desired 1,2,3‐triazolooxazine derivative. Enantiomerically pure azidocyclohexanol was also subjected to the Huisgen 1,3‐dipolar cycloaddition reaction with dimethylacetylene dicarboxylate, followed by intramolecular cyclization of the corresponding cycloadduct, to furnish a fused 1,2,3‐triazolo‐δ‐lactone.     

Synthesis and characterization of substituted salicylate zirconium compounds and their catalytic activity over ε-caprolactone

In this study, zirconium salicylate compounds (1–6) were prepared by reaction of zirconium(IV) propoxide with 5-chlorosalicylic acid, 4-hydroxysalicylic acid, and 5-nitrosalicylic acid in 1-propanol, respectively. All these compounds (1–6) were characterized by ¹H, ¹³C NMR, FTIR, mass spectroscopy, elemental, and thermogravimetric analyses. These compounds were tested as catalysts in polymerization of ε-caprolactone and were effective. Polycaprolactone was characterized by ¹H, ¹³C NMR, and gel permeation chromatography. The number of salicylate ligands (bonded to zirconium atom) effects and substituents (on salicylate ligands) effects on the polymerization reactions were investigated first time by this study.     

Determination of Gallic acid by differential pulse polarography: Application to fruit juices

Phenolic compounds possess antioxidant, antitumor, antimutagenic, antibacterial and anticarcinogenic properties. Gallic acid (2,3,4-trihydroxybenzoic acid) is a natural phenolic compound; therefore, determination of trace gallic acid is very important. In this work, a novel, sensitive and reliable method was developed using differential pulse polarography. The most suitable buffer system was found to be Britton-Robinson (B-R) buffer, pH 10.0. The gallic acid peak in this medium appeared at about ?160 mV, it responded well to standard additions, and high reproducibility was obtained. The calibration graph was linear in the concentration range of gallic acid from 1.0–50.0 μM with a correlation coefficient of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 0.3 and 1.0 μM, respectively. The proposed method was successfully applied to the determination of gallic acid in fruit juices. The influences of some other commonly found inorganic and organic salts on the determination were also examined. Some interferiences were eliminated by using complexing agents, e.g. EDTA.     

Microchip extraction of catecholamines using a boronic acid functional affinity monolith

A novel solid phase extraction microchip with a boronic acid functional affinity monolithic disc was developed in this work. Vinyl phenylboronic acid–ethylene glycol dimethacrylate co-polymer monoliths, which have pore sizes up to 20 μm, were investigated for extraction of catecholamines using adsorption and desorption studies in a batch system. Desorption yields of greater than 90% were achieved for catecholamines at pH 3 and below. Monolithic discs were then formed in chambers in borofloat glass microfluidic chips using in situ UV polymerization. Adsorption on the monolithic discs was performed via electrokinetic flow, with catecholamines determined via laser-induced native fluorescence (LINF) detection following electrokinetic elution. Microchips containing the boronic acid functional polymer discs worked well for extraction of catecholamines, providing greater than 100 fold concentration enrichment. This study demonstrated that a solid phase extraction microchip, containing an easily prepared monolith disc, will be useful for boronate affinity extraction of cis-diol containing compounds.     

Microwave-assisted synthesis and characterization of phthalocyanines substituted with azo compound containing eugenol moiety

The new metallophthalocyanines (Co, Ni, Cu, and Zn) substituted with azo compound containing eugenol moiety are described. Firstly, azo compound (I) containing eugenol moiety was synthesized by treating eugenol with p-hydroxyaniline. Then phthalonitrile compound (1) was synthesized by microwave-assisted synthesis method. The purification of phthalonitrile compound (1) was carried out by column chromatographic separation. Intramolecular hydrogen bonding in the azo compound (I) prevent base-catalyzed nucleophilic aromatic substitution of OH group belongs eugenol. At the last step, metallophthalocyanines (1a, 1b, 1c, and 1d) were synthesized by the microwave irradiation. The microwave-assisted synthesis method reduces reaction times and enhances the yield of the reactions. All phthalocyanine compounds are soluble in DMF and DMSO. The structures were confirmed by elemental analysis, ¹H NMR, ¹³C NMR, UV/Vis, IR and Mass spectra.     

Single step sol-gel made silver chloride on Titania xerogels to inhibit <Emphasis Type="Italic">E. coli</Emphasis> bacteria growth: effect of preparation and chloride ion on bactericidal activity

We report the antibacterial efficacies of silver and/or silver chloride containing titania xerogels synthesized with modified single step sol-gel methods against Escherichia coli bacteria. As the silver loading in TiO₂ increases, the amount of the xerogel required to inhibit the growth of the bacteria decreases and also we found that pure TiO₂ was not bactericidal. Among modified single step sol-gel methods used in this study, the additional HCl treatment sol-gel route III was very effective to obtain only AgCl crystallites in TiO₂. Based on viable cell count method, 0.125 g/L of 29%Ag/TiO₂ (made with HNO₃ sol-gel route I) was enough to inhibit the growth of E. coli whereas 0.6 g/L of 29%Ag/TiO₂ (made with the additional HCl treatment sol-gel route III) was required. However, antibacterial activity of 29%Ag/TiO₂ (made with HNO₃ sol-gel route I) after 6 usages was the same as 29%Ag/TiO₂ (made with the additional HCl treatment sol-gel route III).