Photolytic and free‐radical polymerization of monomethyl maleate esters of epoxidized plant oil triglycerides

Epoxidized soybean oil (ESO) was reacted with monomethyl maleate with AMC‐2 catalyst. Monomethyl maleate was found to react with 65% of the available epoxy groups to give the monomethyl maleic esters of ESO (MESO). ¹H‐NMR, ¹³C‐NMR, and IR spectra of the new derivative confirmed the proposed structure. The NMR spectra revealed that the average number of monomethyl maleate groups per triglyceride molecule was 2.6. MESO was photopolymerized with ultraviolet light and was free radically homopolymerized and copolymerized with styrene (STY), vinyl acetate (VA), and methylmethacrylate (MMA). MESO was also reacted with maleic anhydride at the newly formed hydroxyl groups to give maleinized MESO, (MESOMA), which now contained 4.9 maleate unsaturations per triglyceride. Dynamic mechanical analysis revealed the dynamic modulus for styrene copolymers of MESO and maleinized MESO as 105 and 140 MPa, respectively. Both of these plant oil derived monomers are good candidates for a practical and economical liquid molding resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 626–633, 2007     

Multi-modal control framework for a semi-autonomous wheelchair using modular sensor designs

This paper presents the hardware and software control framework for a semi-auton omous wheelchair. The hardware design incorporates modular and reconfigurable sensors and corresponding low-level software architecture. Two control schemes are discussed. Assisted control that augments the user inputs by providing functionalities such as obstacle avoidance and wall following. And, semi-autonomous navigation which takes higher level destination goals and executes a simultaneous localization and mapping algorithm. We also propose an adaptive motion control with a online parameter estimation. The paper presents both experimental and simulation results.     

The Effects of Containment on Detonation Velocity

Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70 μs⁻¹. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For U_s/C_o≥1.2, where U_s is the detonation velocity and C_o the zero‐pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump‐off. For U_s/C_o≤1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The U_s/C_o≥1.2 cylinders saturate in detonation velocity for thick walls but the U_s/C_o<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15–0.5 power.     

Influence of combined magnetic and electric fields on the behaviour of polyelectrolyte hydrogel

The behaviour of polyelectrolyte gel under the influence of combined electric and magnetic fields has been studied. It is shown that the rate of gel contraction stimulated by an electric field can be significantly changed under the action of an external magnetic field. A qualitative interpretation of the observed phenomenon is given. © 2001 Society of Chemical Industry     

Task-based comparison of inverse methods in magnetoencephalography

Magnetoencephalography (MEG) provides unique insights into the spatio-temporal dynamics of neural activation in the human brain. Unfortunately, the accuracy with which neural sources can be localized is limited by the highly illposed nature of the inverse problem. A large number of inverse methods have been proposed that deal with this illposedness using a range of different modeling and regularization procedures. Here we describe an objective task-based framework for comparing different inverse methods. Using the free-response receiver operating characteristic (FROC) we compare the performance of matched filters, cortically constrained dipole scanning, and minimum norm imaging methods for the task of detecting focal cortical activation. Our results indicate that the scanning methods outperform matched filters and minimum norm imaging for the case of one and two 2 cm2 patches of cortical activity when the dynamics of the two patches are both strongly and weakly correlated and irrespective of the spacing of the two activated regions.     

The analysis of thermoluminescent glow peaks of natural calcite after beta irradiation

In this study, the thermoluminescence properties of natural calcite samples were examined in detail. The glow curve of the sample irradiated with beta radiation shows two main peaks, P1 (at 115 °C) and P4 (at 254 °C). The additive dose, variable heating rate, computer glow curve deconvolution, peak shape and three point methods have been used to evaluate the trapping parameters, namely the order of kinetics (b), activation energy (E) and the frequency factor (s) associated with the dosimetric thermoluminescent glow peaks (P1 and P4) of natural calcite after different dose levels with beta irradiation.     

Systematic mesh development for 3D CFD simulation of fixed beds: Single sphere study

To develop and validate meshes for computational fluid dynamics (CFD) simulations of transport in fixed beds, a single particle is often used as a test case. We present results for drag coefficient (C_D) and heat transfer Nusselt number (Nu) for flow past a sphere, focusing on high flow rates typical of industrial steam reformers (400 < Re < 20,000). Over this range, good predictions of C_D were obtained using large eddy simulation (LES) to capture vortex shedding and wake dynamics, with a mesh refined downstream from the sphere. The small time-steps and high cell count required make this too expensive for fixed beds. Nu can be accurately calculated using a Reynolds-averaged Navier-Stokes (RANS) method with shear-stress transport (SST) k-ω closure provided the mesh at the particle surface is fine enough and covers most of the boundary layer. Single sphere simulations of heat transfer are more useful for fixed bed mesh development than drag coefficient calculations.     

Highly selective ion-imprinted particles for solid-phase extraction of Pb ions

The Pb²⁺-imprinted (PHEMAC-Pb²⁺) particles were prepared by bulk polymerization as a solid-phase extraction (SPE) adsorbent. N-methacryloyl-(l)-cysteine (MAC) was used as functional monomer to have a well-shaped molecular geometry between MAC monomer and Pb²⁺ ions that provide molecular recognition based on well fitted cavities for Pb²⁺ ions after removal of template ions. The PHEMAC-Pb²⁺ particles were characterized and the applicability of these particles was investigated for the solid-phase extraction of Pb²⁺ ions from aqueous solutions and environmental samples. The PHEMAC-Pb²⁺ particles with a size range of 50–200 µm have a rough surface and macropores in bulk structure. The adsorption capacity of the PHEMAC-Pb²⁺ particles is relatively low (2.01 mg/g). However, the high selectivity towards competitive ions (Cd²⁺, Ni²⁺ and Cu²⁺) promises the PHEMAC-Pb²⁺ particles an alternative SPE adsorbent in literature. The relative selectivity coefficients of PHEMAC-Pb²⁺ particles for Pb²⁺/Ni²⁺, Pb²⁺/Cd²⁺ and Pb²⁺/Cu²⁺ were almost 71, 117 and 192 times greater than that of non-imprinted (PHEMAC) particles, respectively. Moreover, the reusability of the PHEMAC-Pb²⁺ particles was tested for several times and no significant loss in adsorption capacity was observed. The accuracy of the proposed procedure was also verified by the determination of Pb²⁺ ions in the certified reference material, LGC 6137 Estuarine sediment.     

Entwicklung einer Methode zur nichtinvasiven Messung des Absolutdrucks in teiltransparenten Gebinden mit karbonisierten Getränken

A non-invasive optical measurement technique for food analysis is presented, which allows for a reliable determination of the absolute pressure in beverage bottles with carbonated contents. The method uses a tunable laser diode with an emission wavelength around 2004 nm to record three to four absorption lines of CO₂ and evaluates the pressure broadening of the lines proportional to the absolute pressure. With the developed measuring method, a standard deviation of repeated absolute pressure measurements of up to 5.5 bar of less than 50 mbar could finally be achieved in field measurements on sealed soft drink bottles made of PET.