Developing electrochemical measurements in order to assess anti-corrosive coatings more effectively

The aim of this project was to check reproducibility of results obtained using NOCS (no connection to the substrate) arrangement of the electrochemical noise method (ENM). NOCS involves taking measurements from three nominally identical areas on the coated surface. Thus, no electrical connection to substrate is required. In practice the areas are not identical and various arrangements for connection of the three cells were tried to see if the individual areas could be separated out and whether the individual resistances could be computed. Also different ways of calculating the R_n (noise resistance) and R_sn (spectral noise resistance) parameters were attempted to see which one gave the best comparison with the more standard EIS measurements. The maximum entropy method was recognized to be the most useful for comparison with EIS, as well as for graphic evaluation of results. Regarding distinguishing three areas using different connection arrangements, it was possible to identify the situation when one of the three values was different to the other two. However further experiments are needed before it will be possible to confidently assign an R_n value to each individual area.     

Design of a Cost‐Reduced Flexible Plant for Supercritical Fluid‐Assisted Applications

A novel batch plant for supercritical CO₂ applications is proposed which is not equipped with expensive components, such as high‐pressure pumps, making it particularly suitable for bench‐scale use. For the first time, the use of a hanging scale is suggested to weigh the amount of CO₂ required for the experiment and the use of the thermodynamics to reach the working conditions. The rig is able to cover different applications, e.g., aerogel drying, impregnation, and extraction, showing high flexibility. An approximate cost analysis has been performed considering as a reference a 150‐mL vessel. It has been calculated that both the setup and running costs are considerably lower than the common batch and semicontinuous rigs.     

Inverse gas chromatography for the determination of the dispersive surface free energy and acid–base interactions of a sheet molding compound. I. Matrix material and glass

Sheet molding compound is a material composed of a polyester thermosetting matrix with a thermoplastic, an inorganic filler, a metal oxide, reinforcement fibers, and material performance enhancers embedded in the crosslinked matrix. To achieve the optimum mechanical properties required for the composite material, the surface free energy of the polyester composite needs to be understood. In this study, the composite matrix and glass reinforcement fibers are compared with respect to their surface free energy and acid–base characteristics on the basis of inverse gas chromatography measurements. The inverse gas chromatography results for the matrix and glass are compared to previous results found for sized and unsized cellulosic fibers. The inverse gas chromatography data are used to assess chemical modifications performed on the biobased fibers to predict improvements in the fiber/matrix interaction, and this provides inferences on the overall composite cohesion. Our results show first that any fiber reinforcement system for the polyester composite material has to be acidic to promote good adhesion as the matrix system is very basic and second that the individual dispersive surface energies of the components of the matrix interact in a weighted average to determine the overall surface energy of the composite. Also, a commercial glass reinforcement sized for polyester has been found to have a lower interaction parameter than literature values for cellulosic fibers. This finding suggests that cellulosic fibers might have an advantage in competing with a conventional glass‐fiber reinforcement system in fiber/matrix bonding for sheet molding compound composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structural Cues for Understanding eEF1A2 Moonlighting

Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the “canonical” one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades.     

The Role of Rigid Residues in Modulating TEM-1 β-Lactamase Function and Thermostability

The relationship between protein motions (i.e., dynamics) and enzymatic function has begun to be explored in β-lactamases as a way to advance our understanding of these proteins. In a recent study, we analyzed the dynamic profiles of TEM-1 (a ubiquitous class A β-lactamase) and several ancestrally reconstructed homologues. A chief finding of this work was that rigid residues that were allosterically coupled to the active site appeared to have profound effects on enzyme function, even when separated from the active site by many angstroms. In the present work, our aim was to further explore the implications of protein dynamics on β-lactamase function by altering the dynamic profile of TEM-1 using computational protein design methods. The Rosetta software suite was used to mutate amino acids surrounding either rigid residues that are highly coupled to the active site or to flexible residues with no apparent communication with the active site. Experimental characterization of ten designed proteins indicated that alteration of residues surrounding rigid, highly coupled residues, substantially affected both enzymatic activity and stability; in contrast, native-like activities and stabilities were maintained when flexible, uncoupled residues, were targeted. Our results provide additional insight into the structure-function relationship present in the TEM family of β-lactamases. Furthermore, the integration of computational protein design methods with analyses of protein dynamics represents a general approach that could be used to extend our understanding of the relationship between dynamics and function in other enzyme classes.     

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.     

Characterization of Novel Pathogenic Variants Causing Pyridox(am)ine 5′-Phosphate Oxidase-Dependent Epilepsy

Several variants of the enzyme pyridox(am)ine 5′-phosphate oxidase (PNPO), responsible for a rare form of vitamin B₆-dependent neonatal epileptic encephalopathy known as PNPO deficiency (PNPOD), have been reported. However, only a few of them have been characterised with respect to their structural and functional properties, despite the fact that the knowledge of how variants affect the enzyme may clarify the disease mechanism and improve treatment. Here, we report the characterisation of the catalytic, allosteric and structural properties of recombinantly expressed D33V, R161C, P213S, and E50K variants, among which D33V (present in approximately 10% of affected patients) is one of the more common variants responsible for PNPOD. The D33V and E50K variants have only mildly altered catalytic properties. In particular, the E50K variant, given that it has been found on the same chromosome with other known pathogenic variants, may be considered non-pathogenic. The P213S variant has lower thermal stability and reduced capability to bind the FMN cofactor. The variant involving Arg161 (R161C) largely decreases the affinity for the pyridoxine 5′-phosphate substrate and completely abolishes the allosteric feedback inhibition exerted by the pyridoxal 5′-phosphate product.     

Glucose kinetics, plasma metabolites, and endocrine responses during experimental ketosis in steers

Phlorizin and 1,3-butanediol were used to determine effects of glucosuria and ketonemia on concentrations of metabolites in blood plasma and on kinetics of glucose metabolism. Four steers received four treatments (control; control plus dietary 1,3-butanediol; control plus phlorizin injections; and control plus phlorizin and 1,3-butanediol) in a Latin square design. Treatments lasted 14 days. All steers received a 30% grain, 70% forage ration in equal meals every 2 h. Metabolite concentrations in blood plasma and urine and glucose kinetics were measured on each of the last 3 days of each treatment period. Phlorizin caused glucosuria; decreased plasma glucose, glucose total entry rate, and glucose recycling; and increased plasma free fatty acids and glucose irreversible loss. Glucose pool size was increased by 1,3-butanediol. Phlorizin plus 1,3-butanediol caused glucosuria and ketonuria; decreased plasma glucose; and increased blood ketone bodies, plasma free fatty acids, glucose irreversible loss, and glucose pool size. Growth hormone, insulin, and glucagon were not affected by treatment. Physiological perturbations in these steers were characteristic of some of those in ketotic cows.     

The quantitative analysis of fat and protein in meat by transmission infrared analysis

Transmission infrared analysis, which has been successfully applied to milk analysis, was assessed for the quantitative analysis of fat and protein in meat products. Meats of varying fat and protein content were converted into milk-like emulsions, which were, in turn, analyzed by standard chemical methods and by a Multispec M infrared analyzer. The performance of the instrument for meat analysis using a standard milk calibration was also assessed and compared with the instrument set with a meat calibration. Both approaches provided a good estimate of the fat and protein content for a range of meat products, the meat calibration being more accurate than the milk calibration. The infrared method allowed for rapid and accurate analysis of meat and has future potential in the meat industry for quality control purposes.