Electrochemical detection of ursolic acid from spruce (Picea abies) essential oils using modified amperometric microsensors

Ursolic acid (UA) is a natural pentacyclic triterpenoid carboxylic acid found in some medicinal plant species. In this paper, amperometric microsensors based on a powder which contained graphite (G) and carbon nanoparticles (CN) (G-CN) unmodified and modified with chitosan (CHIT) and tetraphenyl-porphine cobalt(II) (Co(II)TPP) are proposed for the analysis of UA plant source essential oils obtained from spruce (Picea Abies). Differential pulse voltammetry (DPV) was used to optimize the method and for the determination of ursolic acid from different types of botanical samples. The optimum working pH was 5.00 for the G-CN and (Co(II)TPP)/G-CN microsensors and pH 3.00 for CHIT/G-CN in the presence of a 0.1?mol L^?1 KCl supporting electrolyte. The linear concentration ranges for ursolic acid (UA) were between 0.1 and 100 µmol L^?1 for the unmodified microsensor (G-CN), 0.01, 1 µmol L^?1 for the microsensor modified with chitosan (CHIT/G-CN), and 0.01 and 10 µmol L^?1 for the microsensor modified with (Co(II)TPP)/G-CN). It is the first time these amperometric microsensors have been used for the reliable analysis of ursolic acid (UA) in three original botanical samples obtained from different parts of spruce (Picea abies): resin essential oil, cons essential oil, cons and sprouts essential oil, with recovery rate values up to 99.29%.     

Nash-equilibrium conditions for strategic games

The notion of the Lagrange vector-function is considered for strategic mono and multi criteria games. Nash and Pareto-Nash equilibrium conditions are studied. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Direct Writing of Conducting Polymers

Described herein is a new printing method—direct writing of conducting polymers (CPs)—based on pipette‐tip localized continuous electrochemical growth. A single barrel micropipette containing a metal wire (Pt) is filled with a mixture of monomer, supporting electrolyte, and an appropriate solvent. A droplet at the tip of the pipette contacts the substrate, which becomes the working electrode of a micro‐electrochemical cell confined to the tip droplet and the pipette. The metallic wire in the pipette acts as both counter and reference electrode. Electropolymerization forms the CP on the working electrode in a pattern controlled by the movement of the pipette. In this study, various width poly(pyrrole) 2D and 3D structures are extruded and characterized in terms of microcyclic voltammetry, Raman spectroscopy, and scanning electron microscopy.

     

Tuning fractional PID controllers for a Steward platform based on frequency domain and artificial intelligence methods

In this paper, two methods to tune a fractional-order PI ^λ D ^μ controller for a mechatronic system are presented. The first method is based on a genetic algorithm to obtain the parameter values for the fractionalorder PI ^λ D ^μ controller by global optimization. The second method used to design the fractional-order PI ^λ D ^μ controller relies on an auto-tuning approach by meeting some specifications in the frequency domain. The real-time experiments are conducted using a Steward platform which consists of a table tilted by six servo-motors with a ball on the top of the table. The considered system is a 6 degrees of freedom (d.o.f.) motion platform. The feedback on the position of the ball is obtained from images acquired by a visual sensor mounted above the platform. The fractional-order controllers were implemented and the performances of the steward platform are analyzed.     

Withaferin A—A Promising Phytochemical Compound with Multiple Results in Dermatological Diseases

Withaferin A (WFA) was identified as the most active phytocompound of the plant Withania somnifera (WS) and as having multiple therapeutic/ameliorating properties (anticancer, antiangiogenic, anti-invasive, anti-inflammatory, proapoptotic, etc.) in case of various diseases. In drug chemistry, WFA in silico approaches have identified favorite biological targets, stimulating and accelerating research to evaluate its pharmacological activity—numerous anticancer effects manifested in various organs (breast, pancreas, skin, colon, etc.), antivirals, anti-infective, etc., which are not yet sufficiently explored. This paper is a synthesis of the most relevant specialized papers in the field that are focused on the use of WFA in dermatological diseases, describing its mechanism of action while providing, at the same time, details about the results of its testing in in vitro/in vivo studies.     

Nanomaterials with antioxidant properties,obtained via biotechnology,using the solid state biosynthesis

ABSTRACT

Two nano materials type emulsion (EP and EM), that includes two different bioactive metabolites of Monascus sp. were obtained. Prior obtaining the nanoemulsion, tha enatural extracts, P (Monascus sp.1 – parental strain) and M (Monascus sp.2 - modified strain), were conditioned in order to increase their stability and biodisponibility. The new nanomaterials obtained were tested in terms of physical and chemical characteristics, by dynamic light scattering, infrared spectra and thermal analysis. Biological properties was investigated, by determining the effects of these new bio materials on wound healing and by measuring the antioxidant properties. The results obtained reveal the presence of aggregates with dimensions in the range of 1–100 nm, proving that these bioproducts are nano materials. The infrared spectra indicate the presence of benzene metadisubstituted (bands at 881.25 cm^?1 and 880.4 cm^?1 respectively), which are specific to Monascus metabolites Thermal analysis indicate the similarities between the matrix used in conditioning and the final nano products contains Monascus metabolites. The influence of these nano bio products on cicatrisation process was determined by tests on mices. It was concluded that there is small positive effect of the extracellular EP product. In this case, the bio product increase with 3% the rate of cicatrisation process, in comparison with the witness. All the two nano products show a significant antioxidant properties, with specific quenching rate of 97.7%     

Polymer–silica hybrids obtained by microemulsion polymerization

The styrene (St), butyl acrylate (BuA), and methyl methacrylate (MMA) polymerization in microemulsion in the presence of sodium dodecylsulfate is studied. This process is conducted in the presence of some comonomers having groups that can participate in sol–gel processes: 3(trimethyloxysilyl) propyl methacrylate (MPTS), triethoxy vinylsilane (VTES), and a comonomer with a sulfate group, styrene sodium sulfonate (StSO₃Na). It has been observed that stabile latexes are obtained by radical polymerization at pH = 7, followed by a sol–gel process in the presence of ammonia. Latex particles sizes and zeta potential grow with MTPS concentration and in StSO₃Na presence. VTES effect depends on its reactivity in St, MMA, and BuA copolymerization. Glass transition temperature and thermal decomposing temperature are influences by functional comonomer concentration and chemical structure. The Fourier transform infrared spectrum and inorganic residue growth after organic part thermal decomposition shows the presence of silica in obtained latexes.     

Eshelby tensor for a crack in an orthotropic elastic medium

In the present Note, we provide new analytical expressions of the components of Hill tensor $\mathbb{P}$ (or equivalently the Eshelby tensor $\mathbb{S}$) associated to an arbitrarily oriented crack in orthotropic elastic medium. The crack is modelled as an infinite cylinder along a symmetry axis of the matrix, with low aspect ratio. The three dimensional results obtained show explicitly the interaction between the primary (structural) anisotropy and the crack-induced anisotropy. They are validated by comparison with existing results in the case where the crack is in a symmetry plane. To cite this article: C. Gruescu et al., C. R. Mecanique 333 (2005).