Olive Oil-Based Lipid Emulsions Do Not Influence Platelet Receptor Expression in Comparison to Medium and Long Chain Triglycerides In vitro

Lipid emulsions influence platelet aggregation and receptor expression. However, the effect on platelet function is not fully explained. Therefore, the aim of this study was to examine the influence of the lipids Lipofundin^®, Lipidem^® and ClinOleic^® on surface expressions of P‐selectin, GPIb and GPIIb/IIIa on platelets in vitro. Whole blood was incubated in two different concentrations (0.06 and 0.6 mg/ml) of LCT/MCT, n‐3/LCT/MCT and LCT‐MUFA for 30 min, followed by activation with TRAP‐6 or ADP for flow‐cytometric assay. Rates of P‐selectin, GPIb and GPIIb/IIIa expression were analyzed. There was a significant increase in GPIIb/IIIa‐ and P‐selectin‐expression after incubation with LCT/MCT and n‐3/LCT/MCT at the concentration of 0.6 mg/ml, without and after stimulation with TRAP‐6 and ADP. GPIb was significantly decreased. Accordingly, LCT‐MUFA had no effect on receptor expression of platelets in vitro. We demonstrated that LCT‐MUFA did not activate receptor expression of platelets whereas LCT/MCT significantly increased platelet aggregation in vitro. This finding should be noted for parenteral nutrition of intensive care patients and, in the future, might provide further insight into the pathogenic pathways of acute thromboembolic events. However, prospectively designed clinical studies are needed to support our results.     

A convected particle domain interpolation technique to extend applicability of the material point method for problems involving massive deformations

A new algorithm is developed to improve the accuracy and efficiency of the material point method for problems involving extremely large tensile deformations and rotations. In the proposed procedure, particle domains are convected with the material motion more accurately than in the generalized interpolation material point method. This feature is crucial to eliminate instability in extension, which is a common shortcoming of most particle methods. Also, a novel alternative set of grid basis functions is proposed for efficiently calculating nodal force and consistent mass integrals on the grid. Specifically, by taking advantage of initially parallelogram‐shaped particle domains, and treating the deformation gradient as constant over the particle domain, the convected particle domain is a reshaped parallelogram in the deformed configuration. Accordingly, an alternative grid basis function over the particle domain is constructed by a standard 4‐node finite element interpolation on the parallelogram. Effectiveness of the proposed modifications is demonstrated using several large deformation solid mechanics problems. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of the structure of steady-state solutions for a porous catalyst pellet Part II. Determination of the catastrophic sets

The present paper is a continuation of the problems analysed in Part I (A. Burghardt and M. Berezowski, Chem. Eng. Process., 26 (1989) 45–57) where a method was presented for dividing the global parameter space into regions with different bifurcation diagrams (pellet temperature versus Thiele modulus) by means of a line called the hysteresis variety. The aim of this work is to determine an exact boundary between subregions of the model parameters with different steady-state solutions, contained within the regions defined by the hysteresis variety. Such a boundary is usually termed the catastrophic set.

The model employed, of simultaneous heat and mass transport accompanied by chemical reaction, takes into account concentration gradients inside a catalyst pellet and assumes that the pellet temperature is uniform but different from that of the surrounding fluid.

Two methods have been proposed for the determination of subregions of multiple steady states: an exact method called parametric and an approximate procedure using the limiting relations for the effectiveness factor.

In the parametric method the generalized Thiele modulus is chosen as a parametric variable whose variation from zero to infinity enables the catastrophic set of the parameters θ_o and γ to be determined for β^* = constant. The method has been tested for three basic shapes of catalyst pellet (slab, cylinder and sphere) and reaction orders of 1/4 n 3; an example is shown in the Figures where spherical attention has been given to analysing the structure and location of the subregion with five steady-state solutions of the model equations.

The approximate method, valid strictly for θ → 0 or θ → ∞, can still be applied for values of θ differing considerably from zero and infinity if the magnitude of the error incurred relative to the exact method is taken into account. Assuming the error = 1%, the ranges of θ have been determined where the approximate procedure can be employed. The main advantage of this method is the possibility of obtaining an explicit analytical relation defining the catastrophic set. An example to calculate the catastrophic set using both methods is presented for the catalyst slab, reaction order n = 0.5 and β^* = 0.1.     

Molecular orientation distributions during injection molding of liquid crystalline polymers: Ex situ investigation of partially filled moldings

The development of molecular orientation in thermotropic liquid crystalline polymers (TLCPs) during injection molding has been investigated using two‐dimensional wide‐angle X‐ray scattering coordinated with numerical computations employing the Larson–Doi polydomain model. Orientation distributions were measured in “short shot” moldings to characterize structural evolution prior to completion of mold filling, in both thin and thick rectangular plaques. Distinct orientation patterns are observed near the filling front. In particular, strong extension at the melt front results in nearly transverse molecular alignment. Far away from the flow front shear competes with extension to produce complex spatial distributions of orientation. The relative influence of shear is stronger in the thin plaque, producing orientation along the filling direction. Exploiting an analogy between the Larson–Doi model and a fiber orientation model, we test the ability of process simulation tools to predict TLCP orientation distributions during molding. Substantial discrepancies between model predictions and experimental measurements are found near the flow front in partially filled short shots, attributed to the limits of the Hele–Shaw approximation used in the computations. Much of the flow front effect is however “washed out” by subsequent shear flow as mold filling progresses, leading to improved agreement between experiment and corresponding numerical predictions. POLYM. ENG. SCI.,, 2011. © 2011 Society of Plastics Engineers     

Effect of classroom air quality on students' concentration: results of a cluster-randomized cross-over experimental study

Abstract To assess the effect of indoor air quality as indicated by the median carbon dioxide (CO(2) ) level in the classroom on the concentration performance (CP) of students, a cross-over cluster-randomized experimental study was conducted in 20 classrooms with mechanical ventilation systems. Test conditions 'worse' (median CO(2) level on average 2115?ppm) and 'better' (median CO(2) level on average 1045?ppm) were established by the regulation of the mechanical ventilation system on two days in one week each in every classroom. Concentration performance was quantified in students of grade three and four by the use of the d2-test and its primary parameter 'CP' and secondary parameters 'total number of characters processed' (TN) and 'total number of errors' (TE). 2366 d2-tests from 417 students could be used in analysis. In hierarchical linear regression accounting for repeated measurements, no significant effect of the experimental condition on CP or TN could be observed. However, TE was increased significantly by 1.65 (95% confidence interval 0.42-2.87) in 'worse' compared to 'better' condition. Thus, low air quality in classrooms as indicated by increased CO(2) levels does not reduce overall short-term CP in students, but appears to increase the error rate. PRACTICAL IMPLICATIONS: This study could not confirm that low air quality in classrooms as indicated by increased CO(2) levels reduces short-term concentration performance (CP) in students; however, it appears to affect processing accuracy negatively. To ensure a high level of accuracy, good air quality characterized, for example, by low CO(2) concentration should be maintained in classrooms.     

Stimulus control of antipredator behavior in newborn and juvenile garter snakes (Thamnophis).

Used neonate and juvenile garter snakes (Thamnophis sirtalis, T. melanogaster, and T. butleri) to investigate the role of visual stimuli in mediating antipredator behaviors and to examine the validity of techniques used to assess defensive responses. Experiment 1 demonstrated that a human hand and a model predator were more effective than other stimuli in eliciting defensive responses in neonates with no prior experience with threatening stimuli. Experiment 2 showed that yearlings responded similarly to a realistic predator model and a human hand. Experiment 3 showed that the level of antipredator behaviors was affected by stimulus size. Experiment 4 indicated that the same snakes gave similar quantitative results when tested by different experimenters with the human hand. The final study demonstrated that stimulus movement influenced defensive responses in some species but not others and found litter and experiential effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental determination of longitudinal dispersion in two-phase flow through packing

Experimental correlations for the parameters of the plug-flow model with imposed longitudinal dispersion, i.e. the longitudinal dispersion coefficient and the real mass-transfer coefficient, have been derived. Assuming that the dispersion takes place only on the gas side, concentration profiles of the component being transferred have been measured. From the experimental data correlations were derived allowing to compute the gas-phase Peclet number and the real mass transfer coefficient. The correlations are then used in the further analysis of the influence of longitudinal dispersion on mass transfer in packed columns.