Differential effects of obesity on visceral vs. subcutaneous adipose arteries: role of shear activated Kir2.1 and alterations to the glycocalyx

Obesity imposes well-established deficits to endothelial function. We recently showed that obesity-induced endothelial dysfunction was mediated by disruption of the glycocalyx and a loss of Kir channel flow-sensitivity. However, obesity-induced endothelial dysfunction is not observed in all vascular beds: visceral adipose arteries (VAA), but not subcutaneous adipose arteries (SAA), exhibit endothelial dysfunction. Aim: To determine if differences in SAA vs. VAA endothelial function observed in obesity are attributed to differential impairment of Kir channels and alterations to the glycocalyx. Methods: Mice were fed a normal rodent diet, or a high fat Western diet to induce obesity. Flow-induced vasodilation (FIV) was measured ex vivo. Functional downregulation of endothelial Kir2.1 was accomplished by transducing adipose arteries from mice and obese humans with adenovirus containing a dominant-negative Kir2.1 construct. Kir function was tested in freshly isolated endothelial cells seeded in a flow chamber for electrophysiological recordings under fluid shear. Atomic force microscopy was used to assess biophysical properties of the glycocalyx. Results: Endothelial dysfunction was observed in VAA of obese mice and humans. Downregulating Kir2.1 blunted FIV in SAA, but had no effect on VAA, from obese mice and humans. Obesity abolished Kir shear-sensitivity in VAA endothelial cells and significantly altered the VAA glycocalyx. In contrast, Kir shear-sensitivity was observed in SAA endothelial cells from obese mice and effects on SAA glycocalyx were less pronounced. Conclusions: We reveal distinct differences in Kir function and alterations to the glycocalyx that we propose contribute to the dichotomy in SAA vs. VAA endothelial function with obesity.

Scaling Tableting Processes from Compaction Simulator to Rotary Presses—Mind the Sub-Processes

Compaction simulators are frequently used in the formulation and process development of tablets, bringing about the advantages of flexibility, low material consumption, and high instrumentation to generate the most possible process understanding. However, their capability of resembling general aspects of rotary press compaction and their precision in simulating or mimicking sub-processes such as feeding and filling need to be systematically studied. The effect of material deformation behavior, blend composition, and feeding on tensile strength and simulation precision as compared with rotary presses of different scales is evaluated in this study. Generally, good simulation performance was found for the studied compaction simulator. Compaction profile-sensitivity was demonstrated for highly visco-plastic materials while shear-sensitivity in feeding was demonstrated for lubricated blends of ductile particles. Strategies for the compensation of both in compaction simulator experiments are presented by careful investigation of the compaction stress over time profiles and introduction of a compaction simulator-adapted shear number approach to account for differences in layout and operation mode between compaction simulator and rotary press, respectively. These approaches support the general aim of this study to provide a more straightforward determination of scaling process parameters between rotary press and compaction simulator and facilitate a quicker and more reliable process transfer.

PRELIMINARY STUDIES ON THE INFLUENCE OF NEGATIVE PRESSURE ON ACTIVATED SLUDGE FLOCS

A sludge from municipal wastewater plant operated for biological contaminant removal was exposed to three different negative pressures (-200, -500 and -800 hPa) for three different duration times (30 second, 1 and 2 minutes). Sludge volume index, shear sensitivity of the sludge and activated sludge floc characteristic was the object of the study before and after negative pressure treatment. After the treatment the sludge settled better independently on the pressure value and duration time. The shear sensitivity changed the most when the pressure exposure of -800 hPa was 1 minute and longer. The flocs structure was more open after negative pressur and larger part of activated sludge was comprised by large flocs.

Effects of Initial Micro-Structures on Deformation Behaviors of Commercial Pure Titanium

In this paper, effects of initial micro-structures on deformation behaviors of commercial pure titanium were elaborated by investigating the evolution of dislocation boundary and its adiabatic shear sensitivity. At the low to medium stain rates, the main plastic deformation mechanism of as-annealed commercial pure titanium is dislocation slipping. Meanwhile, geometrically necessary boundaries (GNBs) with different directions are generated and crossed with each other. However, new dislocation boundaries are formed in as-cold rolled plates, which are parallel to the initial ones induced by cold rolling. When the strain rate is up to 1000 s-1, the initial dislocation boundary playes an adverse role in the adiabatic shear sensitivity of commercial pure titanium. The adiabatic shear band is the high-speed deformation characteristic micro-structure in commercial pure titanium. In addition, dynamic recrystallized grains are generated in the center of an adiabatic shear band, which is consistent with the sub-grain rotation mechanism.

Preparation of optimal feedstock for low-pressure injection molding of Al/SiC nanocomposite

This study aims to prepare optimal feedstock for fabrication of Al/SiC nanocomposites by the low-pressure injection molding technique. For this purpose, micron-sized aluminum and nanosized SiC powders were mixed with different amounts of the binder consisting of 89 wt% paraffin wax, 9 wt% bees wax, and 2 wt% stearic acid. Rheometry analyses as well as the Weir model were utilized to determine the optimal feedstock with the desired rheological properties and high homogeneity. Considering powder to binder ratios, shear sensitivity, flow activation energy, and homogeneity within the rheometry analyses, the feedstock of 78 wt% powder loading is selected as the optimal sample for injection molding. Investigation of optimal feedstock by the scanning electron microscopy technique also verified the high homogeneity of this feedstock. In addition, it was observed that all of the feedstocks had thixotrop behavior.