Aging and Degradation in Dilute Polymer Solutions

This paper describes studies of the properties of dilute solutions of polymers which have been found to reduce friction in turbulent flows. The substances tested, in solution in tap water, were guar gum, polyethylene oxide (Union Carbide 'Polyox' WSR 301) and polyacrylamide (Dow 'Separan' AP 30). It had been previously found that solutions of 'Polyox' and 'Separan' exhibit normal-stress difference effects. Correspondingly for'Polyox' solutions, it has been reported that the pressure increment at the mouth of a pitot tube, or open-ended tube facing into the flow, can be reduced below the value [formula] normal for Newtonian liquids, where [Greek rho] is density and V is speed. The present experiments began as a further investigation of this loss of pitot pressure. It was found that the pitot loss reduced with time, and that with 'Polyox' solutions other normal-stress difference effects showed a similar aging, without apparently impairing the ability of the liquid to produce turbulent drag reduction. Continued exposure of the liquid to intense turbulence does, however, lead to a degradation of the drag reduction

The effect of the noncentral impurity-matrix interaction upon the thermal expansion and polyamorphism of solid CO-C60 solutions at low temperatures

Orientational glasses with CO molecules occupying 26% and 90% of the octahedral interstitial sites in the C60 lattice have been investigated by the dilatometric method in a temperature interval of 2.5 - 23 K. At temperatures 4 - 6 K the glasses undergo a first-order phase transition which is evident from the hysteresis of the thermal expansion and the maxima in the temperature dependences of the linear thermal expansion coefficients, and the thermalization times of the samples. The effect of the noncentral CO-C60 interaction upon the thermal expansion and the phase transition in these glasses was clarified by comparing the behavior of the properties of the CO-C60 and N2-C60 solutions.Comment: 11 pages, 7 figure

Influence of metals and metalloids on the composition and fluorescence quenching of the extracellular polymeric substances produced by the polymorphic fungus <i>Aureobasidium pullulans</i>

Aureobasidium pullulansis a ubiquitous and widely distributed fungus in the environment, and exhibits substantial tolerance against toxic metals. However, the interactions between metals and metalloids with the copious extracellular polymeric substances (EPS) produced byA. pullulansand possible relationships to tolerance are not well understood. In this study, it was found that mercury (Hg) and selenium (Se), as selenite, not only significantly inhibited growth ofA. pullulansbut also affected the composition of produced EPS. Lead (Pb) showed little influence on EPS yield or composition. The interactions of EPS fromA. pullulanswith the tested metals and metalloids depended on the specific element and their concentration. Fluorescence intensity measurements of the EPS showed that the presence of metal(loid)s stimulated the production of extracellular tryptophan-like and aromatic protein-like substances. Examination of fluorescence quenching and calculation of binding constants revealed that the fluorescence quenching process for Hg; arsenic (As), as arsenite; and Pb to EPS were mainly governed by static quenching which resulted in the formation of a stable non-fluorescent complexes between the EPS and metal(loid)s. Se showed no significant interaction with the EPS according to fluorescence quenching. These results provide further understanding of the interactions between metals and metalloids and EPS produced by fungi and their contribution to metal(loid) tolerance

Low temperature heat capacity of fullerite C60 doped with nitrogen

The heat capacity Cm of polycrystalline fullerite C60 doped with nitrogen has been measured in the temperature interval 2 - 13 K. The contributions to heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C60 molecules (Einstein contribution) and from the motion of the N2 molecules in the octahedral cavities of the C60 lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first - order phase transformation that had been detected earlier in the dilatometric investigation of the orientational N2-C60 glass. A possible explanation of this fact is proposed.Comment: 4 pages, 2 figures, to be published in Fiz. Nizk. Temp. (Low Temp. Phys.

Actitudes y percepciones de los docentes universitarios en el proceso de adopción de una innovación. La iniciativa OpenCourseWare en la Universidad de Valencia (España)

El proyecto OpenCourseWare, repositorio de recursos educativos en abierto, se inició en la Universidad de Valencia en 2008 y en 2009, sólo incluía 10 asignaturas, ninguna de ellas del área de ciencias de la salud. El objetivo de este trabajo es investigar las actitudes de los docentes de esta área así como sus percepciones con relación a este repositorio para determinar cuáles son las estrategias necesarias para extender su uso. Se parte de la teoría de la difusión de las innovaciones de Rogers (2003) y de un enfoque cualitativo a través del muestreo teórico, entrevistas semiestructuradas y codificación abierta. Los resultados indican la existencia de dos grandes grupos de profesores. Los adoptantes tempranos con una predisposición alta a participar en la iniciativa y con una percepción positiva de sus atributos y los mainstream o corriente principal más reacios a participar y con una percepción negativa respecto a alguno de sus atributos. La identificación de las características de estos dos grandes grupos marca las líneas de acción y de investigación futura en el ámbito del marketing y difusión, formación, sensibilización y motivación para extender el uso del OCW. The OpenCourseWare project, an open learning resource repository, was set up at the University of Valencia between 2008 and 2009. It initially consisted of only 10 subjects, none of which was in the field of health sciences. The objective of this research is to investigate the attitudes and perceptions of teaching staff in the field of health sciences with regard to the project in order to identify strategies to increase its use and expand its coverage. The diffusion of innovations theory as propounded by Rogers is used, along with a qualitative approach using theoretical sampling, semi-structured interviews and open coding. The results indicate the existence of two categories of teaching staff. Firstly, those who adopt an innovation early, have a marked inclination to participate in the initiative and a positive perception of the characteristics of the innovation. Secondly, a larger category of those more reluctant to participate in it and with a negative perception of one or more of its characteristics. Identifying the nature of these two groups provides guidelines for future action and research in the marketing and distribution of such projects, and the training, awareness and motivation required in order to extend the use of OCW

Structure-guided design and optimization of small molecules targeting the protein-protein interaction between the von hippel-lindau (VHL) E3 ubiquitin ligase and the hypoxia inducible factor (HIF) alpha subunit with in vitro nanomolar affinities

E3 ubiquitin ligases are attractive targets in the ubiquitin-proteasome system, however, the development of small-molecule ligands has been rewarded with limited success. The von Hippel-Lindau protein (pVHL) is the substrate recognition subunit of the VHL E3 ligase that targets HIF-1α for degradation. We recently reported inhibitors of the pVHL:HIF-1α interaction, however they exhibited moderate potency. Herein, we report the design and optimization, guided by X-ray crystal structures, of a ligand series with nanomolar binding affinities

Low temperature thermal expansion of pure and inert gas-doped Fullerite C60

The low temperature (2-24 K) thermal expansion of pure (single crystal and polycrystalline) C60 and polycrystalline C60 intercalated with He, Ne, Ar, and Kr has been investigated using high-resolution capacitance dilatometer. The investigation of the time dependence of the sample length variations on heating shows that the thermal expansion is determined by the sum of positive and negative contributions, which have different relaxation times. The negative thermal expansion usually prevails at helium temperatures. The positive expansion is connected with the phonon thermalization of the system. The negative expansion is caused by reorientation of the C60 molecules. It is assumed that the reorientation is of quantum character. The inert gas impurities affect very strongly the reorientation of the C60 molecules especially at liquid helium temperatures. A temperature hysteresis of the thermal expansion coefficient of Kr- and He- C60 solutions has been revealed. The hysteresis is attributed to orientational polyamorphous transformation in these systems.Comment: 18 pages, 12 figure

What lies beneath: exploring links between asylum policy and hate crime in the UK

This paper explores the link between increasing incidents of hate crime and the asylum policy of successive British governments with its central emphasis on deterrence. The constant problematisation of asylum seekers in the media and political discourse ensures that 'anti-immigrant' prejudice becomes mainstr earned as a common-sense response. The victims are not only the asylum seekers hoping for a better life but democratic society itself with its inherent values of pluralism and tolerance debased and destabilised

Multiple cardiac biomarkers to improve prediction of cardiovascular events:Findings from the Generation Scotland Scottish Family Health Study

Background: Many studies have investigated whether single cardiac biomarkers improve cardiovascular risk prediction for primary prevention but whether a combined approach could further improve risk prediction is unclear. We aimed to test a sex-specific combined cardiac biomarker approach for cardiovascular risk prediction. Methods: In the Generation Scotland Scottish Family Health Study, N-terminal pro-B-type natriuretic peptide (NT-proBNP), growth differentiation factor-15 (GDF-15), cardiac troponin I (cTnI), cardiac troponin T (cTnT), and C-reactive protein (CRP) were measured in stored serum using automated immunoassays. Sex-specific Cox models that included SCORE2 risk factors evaluated addition of single and combined biomarkers for prediction of major adverse cardiovascular events (MACE). Combined biomarker models were compared to a baseline model that included SCORE2 factors.Results: The study population comprised 18,383 individuals (58.9% women, median age of 48 years [25th-75th percentile, 35-58 years]). During the median follow up of 11.6 (25th-75th percentile, 10.8-13.0) years, MACE occurred in 942 (5.1%) individuals. The greatest increase in discrimination with addition of individual biomarkers to base model was for women GDF-15 and for men NT-proBNP (change in c-index: +0.010 for women and +0.005 for men). For women, combined biomarker models that included GDF-15 and NT-proBNP (+0.012) or GDF-15 and cTnI (+0.013), but not CRP or cTnT, further improved discrimination. For men, combined biomarker models that included NT-proBNP and GDF-15 (+0.007), NT-proBNP and cTnI (+0.006), or NT-proBNP and CRP (+0.008), but not cTnT, further improved discrimination. Conclusions: A combined biomarker approach, particularly the use of GDF-15, NT-proBNP and cTnI, further refined cardiovascular risk estimates.<br/