X-ray scattering studies on multiphasic polymer systems

The scope of the present chapter had to be limited to some recent studies on the application of synchrotron WAXS and SAXS in three particular multicomponent and multiphase polymer systems. The first system comprises materials that became known as microfibrillar reinforced composites (MFC) produced from oriented blends of thermoplastic semicrystalline polymers by conventional processing techniques. These materials belong to fiber-reinforced composites that have many important engineering applications but are notoriously difficult to study. As a second material system, the structure development during processing of an immiscible polymer blend of polypropylene (PP) and polystyrene (PS) was investigated by X-ray scattering techniques. Structure formation in polymers blends has been widely investigated in the last years, mainly in terms of the development of the size, shape, and orientation of the dispersed component under flow deformation. Further, the structure evolution and damage during stretching in the solid state of polymers blends is much less researched topic. Complementing, this second study, the structure evolution of the PP/PS blend was investigated by time resolved x-ray scattering in a synchrotron source. Finally, the third case reveals investigations on the structure of polymer nanocomposites developed during processing and also during stretching. Polymer nanocomposites are a recent class of materials, and very few studies have been published on the structure development in them.This work was supported by DESY and the European Commission under HASYLAB Projects 18DESYD-II-05-101 EC, DESY-D-II-07-011 EC and the FP6 contract RII3-CT-2004-506008 (IA-SFS). This work was also supported by FCT –Portuguese Foundation for Science and Technology through projectPOCTI/CTM/46940/2002 (MICROTEST) and POCI/CTM/57358/2004 (NANOFIBCO)

Laser induced synthesis of nickel alloy (alumel) nanoparticles in liquids

Pulsed laser ablation in liquids (PLAL) has been growing as a powerful technique for the synthesis of multielement nanoparticles (NPs) such as metal alloys with complex composition. In consequence, there is a great necessity in expanding the current knowledge about alloy NPs formation during this method, aiming to control the chemical composition of produced NPs. In this work, a nanosecond Nd:YAG laser was used to synthesize NPs of a novel nickel (Ni) alloy, and a brief description regarding the influence of liquid media in size and stability of produced nanoparticles is presented. The results showed great stability in the colloids produced in isopropanol medium without using a surfactant, whereas this environment allowed the production of smaller nanoparticles.This work has been supported by FCT (Fundação para a Ciência e Tecnologia – Portugal) in the scope of the projects UID/EEA/04436/2013 and NORTE-01- 0145-FEDER-000018-HAMaBICo. It is also co-funded by National Funds through FCT - Portuguese Foundation for Science and Technology, Reference UID/CTM/50025/2013 and FEDER funds through the COMPETE 2020 Programme under the project number POCI-01-0145-FEDER-007688. Thank the CNPq (205791/2014-0) and CAPES for financial support

Physical properties of ESA Rosetta target asteroid (21) Lutetia: Shape and flyby geometry

Aims. We determine the physical properties (spin state and shape) of asteroid (21) Lutetia, target of the ESA Rosetta mission, to help in preparing for observations during the flyby on 2010 July 10 by predicting the orientation of Lutetia as seen from Rosetta. Methods. We use our novel KOALA inversion algorithm to determine the physical properties of asteroids from a combination of optical lightcurves, disk-resolved images, and stellar occultations, although the latter are not available for (21) Lutetia. Results. We find the spin axis of (21) Lutetia to lie within 5 degrees of ({\lambda} = 52 deg., {\beta} = -6 deg.) in Ecliptic J2000 reference frame (equatorial {\alpha} = 52 deg., {\delta} = +12 deg.), and determine an improved sidereal period of 8.168 270 \pm 0.000 001 h. This pole solution implies the southern hemisphere of Lutetia will be in "seasonal" shadow at the time of the flyby. The apparent cross-section of Lutetia is triangular as seen "pole-on" and more rectangular as seen "equator-on". The best-fit model suggests the presence of several concavities. The largest of these is close to the north pole and may be associated with large impacts.Comment: 17 pages, 5 figures, 3 tables, submitted to Astronomy and Astrophysic

CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories

We present the results of observational campaigns of asteroids performed at Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro Station of Catania Astrophysical Observatory, as part of the large research programme on Solar System minor bodies undertaken since 1979 at the Physics and Astronomy Department of Catania University. Photometric observations of six Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and 984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199 Nefertiti and 2004 UE) are reported. The first determination of the synodic rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the derived synodic period of 80.23+/-0.08 h and 2.981+/-0.001 h, respectively, represents a significant improvement on the previously published values. For 182 Elsa the first determination of the H-G magnitude relation is also presented.Comment: 19 pages, 11 figures, accepted for publication in Planetary and Space Scienc

Influence of transcrystalline layer on finite element mesoscale modeling of polyamide 6 based single polymer laminate composites

This study presents a novel approach for finite element modeling of the elastic behavior of a plain-woven reinforced single polymer laminate composites (WSPC) based on polyamide 6 (PA6). These composites are produced via compression molding of PA6 woven textile structures that are powder-coated by anionic PA6 microparticles. Morphological and structural analysis complemented by electron microscopy, image processing and X-ray diffraction suggest the presence of transcrystalline layer (TCL) at the matrix-reinforcement interface. Having in mid this experimental fact, a novel procedure is developed for finite level discretization of TCL in the representative volume element (RVE) during tensile straining. The procedure correlates the material properties with the overall load applied, thus adequately modelling the tensile behavior of the WSPC based on the constituent materials. The stress field along the elements of the RVE model is studied while the tensile loads were applied in two principal directions. A good agreement between the real mechanical behavior and that calculated based on the model was demonstrated.IPC and 2C2T gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. The authors affiliated to 2C2T acknowledge also partial funding from FCT - Fundação para a Ciência e a Tecnologia within the projects POCI- 01-0145-FEDER-007136 and UID/CTM/00264. S.D. Tohidi thanks to FCT for the PhD Grant SFRH/BD/94759/2013. N. Dourado acknowledges FCT for the financial support through the projects UID/EEA/04436/2013 and POCI-01-0145-FEDER-006941. M. Rezazadeh acknowledges the support provided by FEDER and FCT funds through project POCI-01-0145-FEDER-029485. N.Q. Quyền thanks for the financial support of FCT through the project PESTUID/CTM/00264. A. Zille also acknowledges the FCT Investigator Research contract IF/00071/2015. S. Hesseler and T. Gries gratefully acknowledge the financial support of German Science Foundation (DFG) through the project RE1057/41. Z. Z. Denchev and N. V. Dencheva acknowledge the support by National Funds through FCT, project UID/CTM/50025/2019. N. Dencheva is also grateful for the financial support of FCT in the frames of the strategic project UID/CTM/50025/2013 and the personal program-contract CTTI-51/18-IP

Prevention of Catheter-Related Blood Stream Infection: Back to Basics?

Background: Central venous catheter (CVC)-related infections are a substantial problem in the intensive care unit (ICU). Our infection control team initiated the routine use of antiseptic-coated (chlorhexidine-silver sulfadiazine; Chx-SS) CVCs in our adult ICUs to reduce catheter-associated (CA) and catheter-related (CR) blood stream infection (BSI) as we implemented other educational and best practice standardization strategies. Prior randomized studies documented that the use of Chx-SS catheters reduces microbial colonization of the catheter compared with an uncoated standard (Std) CVC but does not reduce CR-BSI. We therefore implemented the routine use of uncoated Std CVCs in our surgical ICU (SICU) and examined the impact of this change. Hypothesis: The use of uncoated Std CVCs does not increase CR-BSI rate in an SICU. Methods: Prospective evaluation of universal use of uncoated Std CVCs, implemented November 2007 in the SICU. The incidences of CA-BSI and CR-BSI were compared during November 2006-October 2007 (universal use of Chx-SS CVCs) and November 2007-October 2008 (universal use of Std CVCs) by t-test. The definitions of the U.S. Centers for Disease Control and Prevention were used for CA-BSI and CR-BSI. Patient data were collected via a dedicated Acute Physiology and Chronic Health Evaluation (APACHE) III coordinator for the SICU. Results: Annual use of CVCs increased significantly in the last six years, from 3,543 (2001) to 5,799 (2006) total days. The APACHE III scores on day 1 increased from a mean of 54.4 in 2004 to 55.6 in 2008 (p = 0.0010; 95% confidence interval [CI] 1.29-5.13). The mean age of the patients was unchanged over this period, ranging from 58.2 to 59.6 years. The Chx-SS catheters were implemented in the SICU in 2002. Data regarding the specific incidence of CR-BSI were collected beginning at the end of 2005, with mandatory catheter tip cultures when CVCs were removed. Little difference was identified in the incidence of BSI between the interval with universal Chx-SS use and that with Std CVC use. (Total BSI 0.7 vs. 0.8 per 1,000 catheter days; CA-BSI 0.5 vs. 0.8 per 1,000 catheter days; CR-BSI 0.2 vs. 0 per 1,000 catheter days.) No difference was seen in the causative pathogens of CA-BSI or CR-BSI. Conclusion: Eliminating the universal use of Chx-SS-coated CVCs in an SICU with a low background incidence of CR-BSIs did not result in an increase in the rate of CR-BSIs. This study documents the greater importance of adherence to standardization of the processes of care related to CVC placement than of coated CVC use in the reduction of CR-BSI.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90456/1/sur-2E2009-2E082.pd

Lipoprotein‐Associated Phospholipase A2 Activity Is a Marker of Risk But Not a Useful Target for Treatment in Patients With Stable Coronary Heart Disease

Background: We evaluated lipoprotein‐associated phospholipase A2 (Lp‐PLA2) activity in patients with stable coronary heart disease before and during treatment with darapladib, a selective Lp‐PLA2 inhibitor, in relation to outcomes and the effects of darapladib in the STABILITY trial. Methods and Results: Plasma Lp‐PLA2 activity was determined at baseline (n=14 500); at 1 month (n=13 709); serially (n=100) at 3, 6, and 18 months; and at the end of treatment. Adjusted Cox regression models evaluated associations between Lp‐PLA2 activity levels and outcomes. At baseline, the median Lp‐PLA2 level was 172.4 μmol/min per liter (interquartile range 143.1–204.2 μmol/min per liter). Comparing the highest and lowest Lp‐PLA2 quartile groups, the hazard ratios were 1.50 (95% CI 1.23–1.82) for the primary composite end point (cardiovascular death, myocardial infarction, or stroke), 1.95 (95% CI 1.29–2.93) for hospitalization for heart failure, 1.42 (1.07–1.89) for cardiovascular death, and 1.37 (1.03–1.81) for myocardial infarction after adjustment for baseline characteristics, standard laboratory variables, and other prognostic biomarkers. Treatment with darapladib led to a ≈65% persistent reduction in median Lp‐PLA2 activity. There were no associations between on‐treatment Lp‐PLA2 activity or changes of Lp‐PLA2 activity and outcomes, and there were no significant interactions between baseline and on‐treatment Lp‐PLA2 activity or changes in Lp‐PLA2 activity levels and the effects of darapladib on outcomes. Conclusions: Although high Lp‐PLA2 activity was associated with increased risk of cardiovascular events, pharmacological lowering of Lp‐PLA2 activity by ≈65% did not significantly reduce cardiovascular events in patients with stable coronary heart disease, regardless of the baseline level or the magnitude of change of Lp‐PLA2 activity

Glacial Refugia in Pathogens: European Genetic Structure of Anther Smut Pathogens on Silene latifolia and Silene dioica

Climate warming is predicted to increase the frequency of invasions by pathogens and to cause the large-scale redistribution of native host species, with dramatic consequences on the health of domesticated and wild populations of plants and animals. The study of historic range shifts in response to climate change, such as during interglacial cycles, can help in the prediction of the routes and dynamics of infectious diseases during the impending ecosystem changes. Here we studied the population structure in Europe of two Microbotryum species causing anther smut disease on the plants Silene latifolia and Silene dioica. Clustering analyses revealed the existence of genetically distinct groups for the pathogen on S. latifolia, providing a clear-cut example of European phylogeography reflecting recolonization from southern refugia after glaciation. The pathogen genetic structure was congruent with the genetic structure of its host species S. latifolia, suggesting dependence of the migration pathway of the anther smut fungus on its host. The fungus, however, appeared to have persisted in more numerous and smaller refugia than its host and to have experienced fewer events of large-scale dispersal. The anther smut pathogen on S. dioica also showed a strong phylogeographic structure that might be related to more northern glacial refugia. Differences in host ecology probably played a role in these differences in the pathogen population structure. Very high selfing rates were inferred in both fungal species, explaining the low levels of admixture between the genetic clusters. The systems studied here indicate that migration patterns caused by climate change can be expected to include pathogen invasions that follow the redistribution of their host species at continental scales, but also that the recolonization by pathogens is not simply a mirror of their hosts, even for obligate biotrophs, and that the ecology of hosts and pathogen mating systems likely affects recolonization patterns