Specifically, fluid flow-derived shear stresses deactivate leukocytes via actions on the conformational activities of proteins on the cell surface. Because membrane properties affect activities of membranebound proteins, we hypothesized that changes in the physical properties of cell membranes influence PMNL sensitivity to fluid shear stress. For this purpose, we modified PMNL membranes and showed that the cellular mechanosensitivity to shear was impaired whether we increased, reduced, or disrupted the organization of cholesterol within the lipid bilayer. Notably, PMNLs with enriched membrane cholesterol exhibited attenuated pseudopod retraction responses to shear that were recovered by select concentrations of benzyl alcohol (a membrane fluidizer). In fact, PMNL responses to shear positively correlated (R 2 ϭ 0.96; P Ͻ 0.0001) with cholesterol-related membrane fluidity. Moreover, in low-density lipoprotein receptor-deficient (LDLr Ϫ/Ϫ ) mice fed a high-fat diet (a hypercholesterolemia model), PMNL shear-responses correlated (R 2 ϭ 0.5; P Ͻ 0.01) with blood concentrations of unesterified (i.e., free) cholesterol. In this regard, the shear-responses of PMNLs gradually diminished and eventually reversed as free cholesterol levels in blood increased during 8 wk of the high-fat diet. Collectively, our results provided evidence that cholesterol is an important component of the PMNL mechanotransducing capacity and elevated membrane cholesterol impairs PMNL shearresponses at least partially through its impact on membrane fluidity. This cholesterol-linked perturbation may contribute to dysregulated PMNL activity (e.g., chronic inflammation) related to hypercholesterolemia and causal for cardiovascular pathologies (e.g., atherosclerosis).flow; cell deactivation; pseudopod retraction; mechanotransduction; hypercholesterolemia WHETHER ADHERED TO A SURFACE or freely suspended in plasma, polymorphonuclear leukocytes (PMNLs; particularly neutrophils) sense and respond to fluid shear stress (force per unit area acting tangential to the cell surface; dyn/cm 2 ) imposed by blood flow. Specifically, fluid shear stress maintains PMNLs in a deactivated state by reducing or preventing formation of pseudopod(s), a morphological hallmark of an activated PMNL, while at the same time, promoting cleavage of cell surface-associated ␤ 2 (CD18) integrins involved in cell adhesion and migration (30,48). The cell-inactivating action of shear stress is depressed upon treatment of cells with threshold concentrations of biochemical agonists, such as formyl peptide (N-formyl-Met-LeuPhe or FMLP; Ͼ 0.01 M) and platelet-activating factor (Ͼ0.1 M) (15), pointing to circulatory fluid flow as a negative mechano-regulator of PMNL activity in the absence of inflammatory agents, i.e., cell stimulation overrides this negative fluid shear stress control. Moreover, impaired leukocyte responses to shear stress, due to agonist stimulation or a pathologically inflamed state, have been linked to increased PMNL entrapment in the microcirculation of normotensive r...

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For nanofibrous aerogels, a three-dimensional porous structure with interwoven nanofibers as a pore wall has become an urgent demand, and it remains to be a challenge to ensure the mechanical stability and thermal insulation. Other than the reported nanofiber as raw materials to generate three-dimensional cellular nanofibrous aerogels, an alternative low-cost and facile procedure has been proposed here via tactfully utilizing polymer sponge as a template attached with reactive particles, followed by a carbothermal reduction process to realize nanowire growth and their replacement of the original framework. The resulting spongy aerogels with numerous interlaced SiC/Si 3 N 4 nanowires as a skeleton exhibit an ultrahigh porosity of 99.79%. Meanwhile, compressive elasticity after a compression at strain of 35% for 400 cycles, a low thermal conductivity of 23.19 mW/(m K), an excellent absorption capacity of 33.9−95.3 times for varied organic solvents removal, along with flexibility in shape design favored by the initial organic sponge make this nanofibrous aerogel an ideal material for heat shielding, absorption, or catalyst support.

Steel fiber reinforced lightweight-aggregate concrete (SFRLAC) has many advantages applied in structural engineering. In this paper, the autogenous shrinkage and drying shrinkage of SFRLAC for up to 270 days were measured, considering the effects of types of coarse and fine aggregates with the changes of water-to-binder ratio and volume fraction of steel fiber, respectively. The properties of mix workability, apparent density, and compressive strength of SFRLAC were also reported and discussed in relation to above factors. Test results show that the development of autogenous and drying shrinkage of SFRLAC was fast within 28 days and tended to be steady after 90 days. The development of autogenous shrinkage of SFRLAC reduced with the increasing water-to-binder ratio and by using the expanded shale with higher soundness and good water absorption, especially at early age within 28 days; the later drying shrinkage was reduced and the development of drying shrinkage was slowed down with the increasing volume fraction of steel fiber obviously; manufactured sand led to less autogenous shrinkage but greater drying shrinkage than fine lightweight aggregate in SFRLAC. The regularities of autogenous shrinkage and drying shrinkage of SFRLAC expressed as the series of hyperbola are analyzed.

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