Online analysis of products from a direct ethanol fuel cell

Methodology for the online analysis of the main products from a direct ethanol fuel cell (DEFC) has been developed. The liquid exhaust from the fuel cell is first passed through a conductivity cell to determine the concentration of acetic acid and then CO₂ is extracted into a nitrogen stream for determination with a flow-through infrared-based CO₂ sensor. The other major product, acetaldehyde can be obtained by difference from the current. The continuous measurement of these products allows monitoring of changes in product distributions with time and operating conditions, resulting in a simple online system for rapid evaluation of anode catalysts in DEFCs.     

State Reconstruction in Higher Dimensional PDEs with Spatially Varying Parameters

The state estimation problem is considered for a diffusion-reaction system with spatially varying parameters defined on a 3-dimensional rectangular domain with the measured output being restricted to a single surface. For this, a backstepping-based observer design is applied, which enables to obtain the observer gains such that the observer error dynamics decays exponentially in the L₂-norm. At first, an idealized system output restricted to a single surface is assumed as an available measurement. Secondly, in view of a practical realization of the proposed observer, the idealized system output is reconstructed from a set of finite-dimensional measurements. The observer error convergence and the applicability of the proposed approach are evaluated by means of numerical simulations. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Energy-consistent shear coefficients for beams with circular cross sections and radially inhomogeneous materials

An exact computational method for the shear stiffness of beams with circular cross sections and arbitrarily radially inhomogeneous Young’s modulus is presented. We derive the displacement and stress field of a cantilever beam according to 3D theory of elasticity, which requires to solve just a 1D linear boundary value problem. The shear stiffness is obtained by setting the shear strain energy from the exact solution equal to that from technical beam theory. Results and closed analytical formulae are given for several functionally graded and layered cross sections.     

Lepidium graminifolium L.: Glucosinolate Profile and Antiproliferative Potential of Volatile Isolates

Glucosinolates (GSLs) from Lepidium graminifolium L. were analyzed qualitatively and quantitatively by their desulfo-counterparts using UHPLC-DAD-MS/MS technique and by their volatile breakdown products-isothiocyanates (ITCs) using GC-MS analysis. Thirteen GSLs were identified with arylaliphatic as the major ones in the following order: 3-hydroxybenzyl GSL (glucolepigramin, 7), benzyl GSL (glucotropaeolin, 9), 3,4,5-trimethoxybenzyl GSL (11), 3-methoxybenzyl GSL (glucolimnanthin, 12), 4-hydroxy-3,5-dimethoxybenzyl GSL (3,5-dimethoxysinalbin, 8), 4-hydroxybenzyl GSL (glucosinalbin, 6), 3,4-dimethoxybenzyl GSL (10) and 2-phenylethyl GSL (gluconasturtiin, 13). GSL breakdown products obtained by hydrodistillation (HD) and CH₂Cl₂ extraction after hydrolysis by myrosinase for 24 h (EXT) as well as benzyl ITC were tested for their cytotoxic activity using MTT assay. Generally, EXT showed noticeable antiproliferative activity against human bladder cancer cell line UM-UC-3 and human glioblastoma cell line LN229, and can be considered as moderately active, while IC₅₀ of benzyl ITC was 12.3 μg/mL, which can be considered as highly active.     

Natural flavonoids interact with dinitrobenzene system in aprotic media: an electrochemical probing

Three structurally related natural flavonoids (FlOH), quercetin (Q), rutin (R) and morin (M), were investigated by cyclic voltammetry to probe their interactions with hazardous 1,4-dinitrobenzene (1,4-DNB) using a glassy carbon electrode. Scavenging of 1,4-DNB by FlOH was inferred from a positive shift in reduction potential, decrease in anodic peak current, and irreversible electrochemical behavior of 1,4-DNB on increasing the flavonoid concentration. The homogeneous bi-molecular rate constant (k2) was determined using the Nicholson-Shain equation and found to be higher for the dianion. Morin posed a comparatively higher k2 value for its interaction with the 1,4-DNB electrochemical system owing to its more acidic nature and least intramolecular hydrogen bonding. The cyclic voltammetric (CV) results were further supported by HyperchemPM3 quantum mechanical semi-empirical calculations, which point towards E(r)C(i) interactions between flavonoids and 1,4-DNB. The present investigation is biologically significant in terms of natural flavonoidal scavenging activity toward toxins such as dinitroaromatics.     

Trajectory Planning and Feedforward Control Design for the Temperature Distribution in a Cuboid

The design of a feedforward tracking controller is considered for the temperature distribution in a cuboid, where the temperature on a single lateral surface can be arbitrarily prescribed by a control input. It is shown that there exists a so–called flat or basic output, which allows to explicitly derive the inverse infinite–dimensional system representation suitable for trajectory planning and for the determination of the respective control input necessary to track the desired trajectory in open–loop. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Normal- and Reversed-Phase Behaviour of 16,17-Secoestrone Derivatives on Cyanopropyl-Bonded Silica Gel

The retention behaviour of a number of 16,17-secoestrone derivatives has been studied by LC and HPTLC on a polar cyanopropyl-bonded stationary phase using non-aqueous and aqueous-organic mobile phases. The retention behaviour has been discussed in terms of nature of the solute, eluent and stationary phase. The correlation between retention constants of 16,17-secoestrone derivatives obtained from reversed-phases and commercially available ACD log P software (Advanced Chemistry, Toronto, Canada) has also been examined.     

A simplified method for defining air humidification and dehumidification requirements

Nowadays, the use of ventilation systems is very common. In museums and exhibition rooms, they are used to guarantee the optimal temperature and humidity conditions for valuable and irreplaceable objects. Ventilation systems are increasingly used even in residential and office buildings. In Austria and other similar climates, winter outdoor air is very dry. Because of the constant air exchange using a ventilation system, the relative humidity of indoor air is often lower than the comfort limit, so that air humidification is necessary. In the same rooms, air must be dehumidified during the summer months. Humidification and dehumidification should be minimized as they are processes that consume a large amount of energy. The problem is that until now, it has been unclear how much humidification or dehumidification is necessary and could not be calculated easily. In this investigation, a simplified method for determining the humidification and dehumidification demands taking into account the effective moisture capacity of the room was developed. The developed model is used for the calculation of the energy balance and will be integrated into the program for energy certification in Austria.     

Critical issues in breast imaging by vibro-acoustography

Clinically, there are two important issues in breast imaging: detection of microcalcifications and identification of mass lesions. X-ray mammography is the main imaging method used for detection of microcalcification, and ultrasound imaging is normally used for detection of mass lesions in breast. Both these methods have limitations that reduce their clinical usefulness. For this reasons, alternative breast imaging modalities are being sought. vibro-acoustography is an imaging modality that has emerged in recent years. This method is based on low-frequency harmonic vibrations induced in the object by the radiation force of ultrasound. This paper describes potential applications of vibro-acoustography for breast imaging and addresses the critical imaging issues such as detection of microcalcifications and mass lesions in breast. Recently, we have developed a vibro-acoustography system for in vivo breast imaging and have tested it on a number of volunteers. Resulting images show soft tissue structures and calcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using X-ray mammography. The encouraging results from in vitro and in vivo experiments suggest that further development of vibro-acoustography technology may lead to a new clinical tool that can be used to detect microcalcifications as well as mass lesions in breast.