Discrete element reduced‐order modeling of dynamic particulate systems

One of the key technical challenges associated with modeling particulate processes is the ongoing need to develop efficient and accurate predictive models. Often the models that best represent solids handling processes, like discrete element method (DEM) models, are computationally expensive to evaluate. In this work, a reduced‐order modeling (ROM) methodology is proposed that can represent distributed parameter information, like particle velocity profiles, obtained from high‐fidelity (DEM) simulations in a more computationally efficient fashion. The proposed methodology uses principal component analysis (PCA) to reduce the dimensionality of the distributed parameter information, and response surface modeling to map the distributed parameter data to process operating parameters. This PCA‐based ROM approach has been used to model velocity trajectories in a continuous convective mixer, to demonstrate its applicability for pharmaceutical process modeling. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3184–3194, 2014     

Modulation of Amyloid‐β Aggregation by Histidine‐Coordinating Cobalt(III) Schiff Base Complexes

Oligomers of the Aβ42 peptide are significant neurotoxins linked to Alzheimer's disease (AD). Histidine (His) residues present at the N terminus of Aβ42 are believed to influence toxicity by either serving as metal–ion binding sites (which promote oligomerization and oxidative damage) or facilitating synaptic binding. Transition metal complexes that bind to these residues and modulate Aβ toxicity have emerged as therapeutic candidates. Cobalt(III) Schiff base complexes (Co–sb) were evaluated for their ability to interact with Aβ peptides. HPLC‐MS, NMR, fluorescence, and DFT studies demonstrated that Co–sb complexes could interact with the His residues in a truncated Aβ16 peptide representing the Aβ42 N terminus. Coordination of Co–sb complexes altered the structure of Aβ42 peptides and promoted the formation of large soluble oligomers. Interestingly, this structural perturbation of Aβ correlated to reduced synaptic binding to hippocampal neurons. These results demonstrate the promise of Co–sb complexes in anti‐AD therapeutic approaches.     

Pultrusion update

The 7th World Pultrusion Conference organised by the European Pultrusion Technology Association (EPTA) took place in Amsterdam on 25-26 March. Amanda Jacob reports on some of the highlights.     

Effects of ultrasonication on the characteristics of emulsions and microparticles containing Indian clove essential oil

The effects of the emulsification method [either mechanical agitation or ultrasonication (US)] and proportion of gum arabic (GA)/maltodextrin (MD) on the characteristics of feed emulsions and microparticles containing Indian clove essential oil produced by spray drying were investigated. Emulsions produced using US were more stable with smaller droplets, lower polydispersity indexes, and higher viscosities. Increasing the proportion of GA resulted in an increased particle size. Powders produced by US exhibited a higher moisture content and hygroscopicity. The US improved oil retention, except for microparticles comprised GA. Powders with a higher proportion of MD exhibited smooth surfaces.     

Cold Exposure Drives Weight Gain and Adiposity following Chronic Suppression of Brown Adipose Tissue

Therapeutic activation of thermogenic brown adipose tissue (BAT) may be feasible to prevent, or treat, cardiometabolic disease. However, rodents are commonly housed below thermoneutrality (~20 °C) which can modulate their metabolism and physiology including the hyperactivation of brown (BAT) and beige white adipose tissue. We housed animals at thermoneutrality from weaning to chronically supress BAT, mimic human physiology and explore the efficacy of chronic, mild cold exposure (20 °C) and β3-adrenoreceptor agonism (YM-178) under these conditions. Using metabolic phenotyping and exploratory proteomics we show that transfer from 28 °C to 20 °C drives weight gain and a 125% increase in subcutaneous fat mass, an effect not seen with YM-178 administration, thus suggesting a direct effect of a cool ambient temperature in promoting weight gain and further adiposity in obese rats. Following chronic suppression of BAT, uncoupling protein 1 mRNA was undetectable in the subcutaneous inguinal white adipose tissue (IWAT) in all groups. Using exploratory adipose tissue proteomics, we reveal novel gene ontology terms associated with cold-induced weight gain in BAT and IWAT whilst Reactome pathway analysis highlights the regulation of mitotic (i.e., G2/M transition) and metabolism of amino acids and derivatives pathways. Conversely, YM-178 had minimal metabolic-related effects but modified pathways involved in proteolysis (i.e., eukaryotic translation initiation) and RNA surveillance across both tissues. Taken together these findings are indicative of a novel mechanism whereby animals increase body weight and fat mass following chronic suppression of adaptive thermogenesis from weaning. In addition, treatment with a B3-adrenoreceptor agonist did not improve metabolic health in obese animals raised at thermoneutrality.     

Cortico-striatal contributions to category learning: Dissociating the verbal and implicit systems.

To better characterize the neuropsychological mechanisms of implicit and verbalizable category learning, the author studied weather prediction task (WPT) and information integration task (IIT) performance in patients with Parkinson's disease (PD) and healthy older and younger adults. Both older adults and patients with PD were impaired on the WPT, but only patients were impaired on the IIT, suggesting the 2 tasks rely on dissociable systems. Whereas the IIT appeared to rely on implicit processes, results suggest WPT classification depends on explicit processes. Awareness of underlying structure, hypothesis testing ability, and working memory capacity were all related to accuracy on the WPT but not the IIT. The variability commonly noted in WPT performance may reflect individual differences in hypothesis testing ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of the Mass Yield in the Biodiesel Production from Chicken Viscera Oil

This work proposes the conversion of chicken viscera oil into biodiesel through the transesterification reaction using basic catalysis. For this, the properties of the raw material and the interferences of the variables on the mass yield of the chemical procedure were evaluated, such as reaction temperature (50–90 °C), catalyst concentration (0.5–2.5% m/m), oil: alcohol molar ratio (1:3 to 1:15) and reaction time (15–75 min).Through the execution of an experimental design procedure and subsequent application of the response surface methodology it was possible to maximize the yield of the transesterification reaction to 87.41% w/w, using the following experimental conditions: reaction temperature 70 °C, catalyst concentration 1% m/m, molar ratio 1:9, and reaction time 30 min. This result provides a reduction of 200% in the percentage of the catalyst used, 67% in the volume of alcohol, and 700% in the reaction time when compared to works using similar raw material published in the literature. Besides, the quality of the biodiesel produced was verified and is following the standards required by ASTM D6751 and EN 14214.     

Amino-functionalized carbon nanotubes for effectively improving the mechanical properties of pre-impregnated epoxy resin/carbon fiber

Pre-impregnated carbon fiber/epoxy resin (CF/epoxy prepreg) gained its popularity for significant stress applications, especially in the aerospace industry, owing to its excellent resistance and low specific mass. However, these CF/epoxy prepregs have a tendency to crack propagation. A solution for the prepregs fragility is the addition of carbon nanotubes (CNTs), especially those functionalized with amino groups, reinforcing the material due to its exceptional mechanical properties. In this work, the influence of the carbon chain length of two different amino-functionalized CNTs from diverse backgrounds (commercial and laboratory growth CNTs) is studied. The nanofillers were added in CF/epoxy prepregs by dry spraying without solvent aid. CNTs' samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA), while the composites were analyzed by TGA, dynamic-mechanical analysis, and field emission scanning electron microscopy. The various surface treatment occurred at different levels according to the CNTs background, and all samples exhibited a distinct behavior. These differences were also observed in the composites' thermomechanical performance: CNTs functionalized with larger carbon chain amine presented the best results, with an increase of almost 100% in the storage moduli (E'), confirming the efficiency of amino-functionalized CNTs in the reinforcement of CF/epoxy prepregs.