Adsorption of organics in the aqueous phase is an area which is experimentally difficult to measure, while computational techniques require extensive configurational sampling of the solvent and ...adsorbate. This is exceedingly computationally demanding, which excludes its routine use. If implicit solvent could be applied instead, this would dramatically reduce the computational cost as configurational sampling of solvent is not needed. Here, using statistical thermodynamic arguments and DFT calculations with implicit solvent models, we show that semiquantitative values for the free energy and entropy change of adsorption in the aqueous phase (ΔG ads solv and ΔS ads solv) for small organics can be calculated, for a range of coverages. We parametrize the soft sphere based solute dielectric cavity to an approximated free energy of solvation for a single Pt atom at the (111) facet, forming upper and lower bounds based on the entropy of water at the aqueous metal interface (ΔG solv(Pt) = −4.35 to −7.18 kJ mol–1). This captures the decrease in ΔG ads solv compared to the free energy of adsorption in the vacuum phase (ΔG ads vac), while solvent models with electron density based cavities fail to do so. For a range of oxygenated aromatics, the adsorption energetics using horizontal gas phase geometries significantly overestimate ΔG ads solv compared to experiment by ∼100 kJ mol–1, but they agree with ab initio MD simulations using similar geometries. This suggests oxygenated aromatic compounds adsorb perpendicular to the metallic surface, while the ΔG ads solv for vertical geometries of furfural and cyclohexanol agree to within 20 kJ mol–1 of experimental studies. The proposed techniques provide an inexpensive toolset for validation and prediction of adsorption energetics on solvated metallic surfaces, which could be further validated by the future availability of more experimental measurements for the aqueous entropy/free energy of adsorption.
The use of computers in manufacturing has enabled the development of several new sheet metal forming processes, which are based upon older technologies. This paper describes modifications that have ...been made to traditional forming methods such as conventional spinning and shear forming, forming processes in which deformation is localized. Recent advances have enabled this localized deformation to be accurately controlled and studied. Current developments have been focused on forming asymmetric parts using CNC technology, without the need for costly dies. Asymmetric Incremental Sheet Forming has the potential to revolutionize sheet metal forming, making it accessible to all levels of manufacturing. This paper describes the genesis and current state-of-the-art of Asymmetric Incremental Sheet Forming.
A friction model for microforming Jeon, J.; Bramley, A. N.
International journal of advanced manufacturing technology,
05/2007, Letnik:
33, Številka:
1-2
Journal Article
Recenzirano
For the simulation of metal forming processes, input data relating to the tool–workpiece interface is necessary. For microforming applications, this input data becomes very much more critical and ...traditional methods are not realistic. This paper describes an approach that seeks to describe friction by modelling the geometric surface roughness of the tool. This finite-element-based model has been validated experimentally in terms of loads and metal forming using the ring test and actual surface measurements. It enables more accurate and also more flexible modelling of friction.
The etiology of community-acquired pneumonia requiring hospitalization in adults is evolving, in light of vaccine deployment and new diagnostic tests. This article defines pathogens potentially ...causing pneumonia. In a majority of cases, no pathogen was identified.
Pneumonia is a leading infectious cause of hospitalization and death among adults in the United States,
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,
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with medical costs exceeding $10 billion in 2011.
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Routine administration of the pneumococcal conjugate vaccine in children has resulted in an overall reduction in the rate of invasive disease and pneumonia among adults, owing to herd immunity.
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–
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The last U.S. population–based incidence estimates of hospitalization due to community-acquired pneumonia were made in the 1990s,
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before the availability of the pneumococcal conjugate vaccine and more sensitive molecular and antigen-based laboratory diagnostic tests. Thus, contemporary population-based etiologic studies involving U.S. adults with pneumonia are . . .
Infection of the mammary gland, in addition to causing animal distress, is a major economic burden of the dairy industry. Staphylococcus aureus is the major contagious mastitis pathogen, accounting ...for approximately 15-30% of infections, and has proved difficult to control using standard management practices. As a first step toward enhancing mastitis resistance of dairy animals, we report the generation of transgenic mice that secrete a potent anti-staphylococcal protein into milk. The protein, lysostaphin, is a peptidoglycan hydrolase normally produced by Staphylococcus simulans. When the native form is secreted by transfected eukaryotic cells it becomes glycosylated and inactive. However, removal of two glycosylation motifs through engineering asparagine to glutamine codon substitutions enables secretion of Gln(125,232)-lysostaphin, a bioactive variant. Three lines of transgenic mice, in which the 5'-flanking region of the ovine beta-lactoglobulin gene directed the secretion of Gln(125,232)-lysostaphin into milk, exhibit substantial resistance to an intramammary challenge of 104 colony-forming units (c.f.u.) of S. aureus, with the highest expressing line being completely resistant. Milk protein content and profiles of transgenic and nontransgenic mice are similar. These results clearly demonstrate the potential of genetic engineering to combat the most prevalent disease of dairy cattle.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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