Predictive Capability of Cardiopulmonary and Exercise Parameters From Day 1 to 6 Months After Acute Pulmonary Embolism.

We hypothesized that the slope of relation ventilation to carbon dioxide output (V'E/V'CO2-slope) could be predictive already during the very first days after submassive pulmonary embolism (PE) to right ventricular systolic pressure (RVsys by echocardiography) after 6 months. We evaluated 21 hemodynamically stable patients at admittance, at days 3, 7, 90, and 180 by cardiopulmonary exercise testing and echocardiography. V'E/V'CO2-slope (48.4 ± 10.8) decreased within the first week (43.0 ± 9.8 at day 7) and normalized until follow-up at 6 months (35.0 ± 11.3; P < 10-4), p(a-ET)CO2 remained abnormal between days 1 and 3 (5.0 ± 3.9 to 6.7 ± 5.3 mmHg). RVsys declined from 41.7 ± 14.3 to 26.3±13.1 mmHg (P < 10-4) at 6 months. V'E/V'CO2-slope (r²= 0.27; P < .02) and RVsys (r² = 0.28; P = .03) at day 7 correlated with RVsys at 6 months. p(a-ET)CO2, p(a-ET)O2, V'D/V'T were not related to RVsys after 6 months. RVsys 6 months after acute PE is positively correlated with the V'E/V'CO2-slope at day 7.

Temperature dependence of the hydrogen bond network in trimethylamine N-oxide and guanidine hydrochloride-water solutions.

We present an X-ray Compton scattering study on aqueous trimethylamine N-oxide (TMAO) and guanidine hydrochloride solutions (GdnHCl) as a function of temperature. Independent from the concentration of the solvent, Compton profiles almost resemble results for liquid water as a function of temperature. However, the number of hydrogen bonds per water molecule extracted from the Compton profiles suggests a decrease of hydrogen bonds with rising temperature for all studied samples, and the differences between water and the solutions are weak. Nevertheless, the data indicate a reduced bond weakening with rising TMAO concentration up to 5 M of 7.2% compared to 8% for pure water. In contrast, the addition of GdnHCl appears to behave differently for concentrations up to 3.1 M with a weaker impact on the temperature response of the hydrogen bond structure.

Microsecond Structural Rheology.

The relationship between the local structure of complex liquids and their response to shear is generally not well understood. This concerns, in particular, the formation of particle strings in the flow direction or hydroclusters, both important for the understanding of shear thinning and thickening phenomena. Here, we present results of a microfocus X-ray scattering experiment on spherical silica colloids in a liquid jet at high shear rates. Along and across the jet, we observe direction-dependent modifications of the structure factor of the suspension, suggesting the formation of differently ordered clusters in compression lines and as particle strings. With increasing distance from the orifice, the structure relaxes to the unsheared case with a typical relaxation 10 times larger as the time scale of Brownian motion. These results provide the first experimental flow characterization of a complex fluid at high shear rates detecting cluster formation and relaxation with micrometer and microsecond resolution.

Intramolecular structure and energetics in supercooled water down to 255 K.

We studied the structure and energetics of supercooled water by means of X-ray Raman and Compton scattering. Under supercooled conditions down to 255 K, the oxygen K-edge measured by X-ray Raman scattering suggests an increase of tetrahedral order similar to the conventional temperature effect observed in non-supercooled water. Compton profile differences indicate contributions beyond the theoretically predicted temperature effect and provide a deeper insight into local structural changes. These contributions suggest a decrease of the electron mean kinetic energy by 3.3 ± 0.7 kJ (mol K)(-1) that cannot be modeled within established water models. Our surprising results emphasize the need for water models that capture in detail the intramolecular structural changes and quantum effects to explain this complex liquid.

Nano-beam X-ray microscopy of dried colloidal films.

We report on a nano-beam small angle X-ray scattering study on densely-packed, dried binary films made out of spherical silica particles with radii of 11.2 and 19.3 nm. For these three-dimensional thin films prepared by drop casting, only a finite number of colloidal particles contributes to the scattering signal due to the small beam size of 400 × 400 nm(2). By scanning the samples, the structure and composition of the silica particle films are determined spatially resolved revealing spatial heterogeneities in the films. Three different types of domains were identified: regions containing mainly large particles, regions containing mainly small particles, and regions where both particle species are mixed. Using the new angular X-ray cross-correlations analysis (XCCA) approach, spatial maps of the local type and degree of orientational order within the silica particle films are obtained. Whereas the mixed regions have dominant two-fold order, weaker four-fold and marginal six-fold order, regions made out of large particles are characterized by an overall reduced orientational order. Regions of small particles are highly ordered showing actually crystalline order. Distinct differences in the local particle order are observed by analyzing sections through the intensity and XCCA maps. The different degree of order can be understood by the different particle size polydispersities. Moreover, we show that preferential orientations of the particle domains can be studied by cross-correlation analysis yielding information on particle film formation. We find patches of preferential order with an average size of 8-10 µm. Thus, by this combined X-ray cross-correlation microscopy (XCCM) approach the structure and orientational order of films made out of nanometer sized colloids can be determined. This method will allow to reveal the local structure and order of self-assembled structures with different degree of order in general.

The effect of polyglycerol sulfate branching on inflammatory processes.

In this study, the extent to which the scaffold architecture of polyglycerol sulfates affects inflammatory processes and hemocompatibility is investigated. Competitive L-selectin binding assays, cellular uptake studies, and blood compatibility readouts are done to evaluate distinct biological properties. Fully glycerol based hyperbranched polyglycerol architectures are obtained by either homopolymerization of glycidol (60% branching) or a new copolymerization strategy of glycidol with ethoxyethyl glycidyl ether. Two polyglycerols with 24 and 42% degree of branching (DB) are synthesized by using different monomer feed ratios. A perfectly branched polyglycerol dendrimer is synthesized according to an iterative two-step protocol based on allylation of the alcohol and subsequent catalytic dihydroxylation. All the polyglycerol sulfates are synthesized with a comparable molecular weight and degree of sulfation. The DB make the different polymer conjugates perform different ways. The optimal DB is 60% in all biological assays.