4,4‐Dimethyl‐ and Diastereomeric 4‐Hydroxy‐4‐methyl‐ (2S)‐Glutamate Analogues Display Distinct Pharmacological Profiles at Ionotropic Glutamate Receptors and Excitatory Amino Acid Transporters

Subtype‐selective ligands are of great interest to the scientific community, as they provide a tool for investigating the function of one receptor or transporter subtype when functioning in its native environment. Several 4‐substituted (S)‐glutamate (Glu) analogues were synthesized, and altogether this approach has provided important insight into the structure–activity relationships (SAR) for ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs), as well as the excitatory amino acid transporters (EAATs). In this work, three 4,4‐disubstituted Glu analogues 1 – 3 , which are hybrid structures of important 4‐substituted Glu analogues 4 – 8 , were investigated at iGluRs and EAATs. Collectively, their pharmacological profiles add new and valuable information to the SAR for the iGluRs and EAAT1–3.     

Carbonation of calcium-containing mineral and industrial by-products

The use of carbon dioxide (CO₂) and calcium-containing by-products from industrial activities is receiving increasing interest as a route to valuable carbonate materials while reducing CO₂ emissions and saving natural resources. In this work, wet-chemical experimental data was assessed, which involved the carbonation of three types of materials in aqueous solutions, namely, 1) wollastonite, a calcium silicate mineral, 2) steelmaking slag, a by-product of steel production, and 3) paper bottom ash (PBA) from waste paper incineration. Aims were to achieve either a high carbonation degree and/or a pure carbonate product with potential commercial value. Producing a pure precipitated calcium carbonate (PCC) material that may find use in paper industry products puts strong requirements on purity and brightness. The parameters investigated were particle size, CO₂ pressure, temperature, solid/liquid ratio, and the use of additives that affect the solubilities of CO₂ and/or calcium carbonate. Temperatures and pressures were varied up to 180°C and 4 MPa. Data obtained with the wollastinite mineral allowed for a comparison between natural resources and the industrial by-product materials, the latter typically being more reactive. With respect to temperature and pressure trends reported by others were largely confirmed, with temperatures above 150°C introducing thermodynamic limitations depending on CO₂ pressure. The influence of additives showed some promise, although costs may make recycling and reuse of additives a necessity for a large-scale process. When using steelmaking slag, magnetic separation may remove some iron-containing material from the process (although this is far from perfect), while the addition of bicarbonate supported the removal of phosphorous, aside from improving calcium extraction. The experiments with paper bottom ash (PBA) gave new data, showing that its reactivity resembles that of steelmaking slag, while its composition results in relatively pure carbonate product. Also, with PBA no additives were needed to achieve this.     

CFD simulation of the high shear mixing process using kinetic theory of granular flow and frictional stress models

In order to enhance process understanding and to develop predictive process models in high shear granulation, there is an ongoing search for simulation tools and experimental methods to model and measure the velocity and shear fields in the mixer. In this study, the Eulerian-Eulerian approach to model multiphase flows has been used to simulate the mixer flow. Experimental velocity profiles for the solid phase at the wall in the mixer have been obtained using a high speed camera following the experimental procedure as described by Darelius et al. [2007a. Measurement of the velocity field and frictional properties of wet masses in a high shear mixer. Chemical Engineering Science, 62, 2366-2374]. The governing equations for modelling the dense mixer flow have been closed by using closure relations from the kinetic theory of granular flow (KTGF) combined with frictional stress models. The free slip and partial slip boundary conditions for the solid phase velocity at the vessel wall have been utilized. The partial slip model originally developed for dilute flows by Tu and Fletcher [1995. Numerical computation of turbulent gas-solid particle flow in a 90^° bend. A.I.Ch.E. Journal, 41, 2187-2197] has been employed. It was found that the bed height could be well predicted by implementing the partial slip model, whereas the free slip model could not capture the experimentally found bed height satisfactorily. In the simulation, the swirling motion of the rotating torus formed was over-predicted and the tangential wall velocity was under-predicted, probably due to the fact that the frictional stress model needs to be further developed, e.g. to tackle cohesive particles in dense flow. The advantage of using the Eulerian-Eulerian approach compared to discrete element methods is that there is no computational limitation on the number of particles being modelled, and thus manufacturing scale granulators can be modelled as well.     

Exposure to diesel exhaust induces changes in EEG in human volunteers

Background  

Ambient particulate matter and nanoparticles have been shown to translocate to the brain, and potentially influence the central nervous system. No data are available whether this may lead to functional changes in the brain.     

Intumescent foams—A novel flame retardant system for flexible polyurethane foams

A combination of intumescent components was evaluated as a novel flame retardant system in a flexible polyurethane foam, and the incorporation of these components gave rise to a significant enhancement of the flame retardant properties of the foam. The heat release rate was lowered at an early stage as well as throughout the fire, the total heat production was decreased and the time to ignition was prolonged. Mechanical measurements of the foam revealed enhanced properties in terms of stiffness accompanied by a large decrease in elongation at break as compared with a reference foam. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The reaction of NiO/NiAl2O4 particles with alternating methane and oxygen

The reduction and oxidation behaviour of oxygen carrier particles of NiO and NiAl₂O₄ has been investigated in a fluidized bed reactor as well as a thermogravimetric analyzer (TGA). The particles showed high reactivity and gas yield to CO₂ with methane in the temperature interval 750–950°C. In the fluidized bed the yield to CO₂ was between 90 and 99% using bed masses corresponding to 16–57 kg/MW_fuel. Complementary experiments in a TGA at 750 and 950°C showed a clear reaction of the NiAl₂O₄ with CH₄ at the higher temperature. There was methane released from the reactor at high degrees of solid oxidation, which is likely associated with the lack of Ni‐sites on the particles which can reform the methane. There was some carbon formation during the reduction, although the amount was minor when the gas yield to carbon dioxide and degree of oxidation of the solid was high. A simple reactor model using kinetic data from a previous study predicted the gas yield during the reduction in the fluidized bed experiments with reasonable accuracy. The oxygen carrier system investigated in this work shows high promise for use in a real CLC system, provided that the particle manufacturing process can be scaled up with reasonable cost.     

ESR studies of the effect of zeolite structures on motional dynamics of NO2

Electron spin resonance (ESR) spectroscopy was used to study the effect of zeolite structure on the motional dynamics of NO₂ adsorbed on the zeolites. The temperature-dependent ESR spectral line shapes were quantitatively analyzed using the slow-motion ESR theory. It was observed that the motional dynamics of NO₂ is strongly dependent on the structure of the zeolite (Beta-type, ZSM-5, mordenite, L-type and ferrierite zeolites). The following important observations were made. (1) In zeolites with similar channel structures, the diffusion rate of NO₂ is proportional to the channel size, and the order of the diffusion rates is Beta-type>ZSM-5>ferrierite and L-type>mordenite. (2) The diffusion of NO₂ is faster in the zeolites with multi-dimensional channels (Beta-type, ZSM-5 and ferrierite) than that in those with uni-dimensional channels (L-type and mordenite).     

Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron

This study focuses on the modelling and simulation of local mechanical properties of compacted graphite iron cast at different section thicknesses and three different levels of silicon, ranging from about 3.6% up to 4.6%. The relationship between tensile properties and microstructure is investigated using microstructural analysis and statistical evaluation. Models are generated using response surface methodology, which reveal that silicon level and nodularity mainly affect tensile strength and 0.2% offset yield strength, while Young′s modulus is primarily affected by nodularity. Increase in Si content improves both the yield and tensile strength, while reduces elongation to failure. Furthermore, mechanical properties enhance substantially in thinner section due to the high nodularity. The obtained models have been implemented into a casting process simulation, which enables prediction of local mechanical properties of castings with complex geometries. Very good agreement is observed between the measured and predicted microstructures and mechanical properties, particularly for thinner sections.     

A virtual machine concept for real-time simulation of machine tool dynamics

When designing CNC machine tools it is important to consider the dynamics of the control, the electrical components and the mechanical structure of the machine simultaneously. This paper describes the structure and implementation of a concept for real-time simulation of such machine tools using a water jet cutting machine as an application. The concept includes a real control system, simulation models of the dynamics of the machine and a virtual reality model for visualisation. The real-time capability of the concept, including the simulation of electrical and rather detailed mechanical component models is proofed. The validation process indicates good agreement between simulation and measurement, but suggests further studies on servo motor, connection and flexibility modelling. However, already from the initial simulation results presented in this paper it can be concluded that the influence of structural flexibility on manufacturing accuracy is of importance at desired feeding rates and accelerations. The fully automated implementation developed in this work is a promising base for dealing with this trade-off between productivity and accuracy of the manufacturing process through multidisciplinary optimisation.     

Modeling continuous electropermutation with effects of water dissociation included

The repeating unit consisting of a cell pair of one concentrate and one feed compartment of an electropermutation stack is modeled. Both the feed and the concentrate compartments are filled with an ion‐exchange textile material. Enhanced water dissociation taking place at the surface of the membrane is included in the model as a hetrogeneous surface reaction. Results from simulations of nitrate removal for drinking water production are presented and comparisons with previous experimental results are made. The influence of both conductive and inert textile spacers on the process is investigated via simulations. © 2010 American Institute of Chemical Engineers AIChE J, 2010