Modeling adsorption reactions of ammonium perchlorate on rutile and anatase surfaces.

In this work, the effects of two TiO2 polymorphs on the decomposition of ammonium perchlorate (NH4ClO4) were studied experimentally and theoretically. The interactions between AP and various surfaces of TiO2 were modeled using density functional theory (DFT) calculations. Specifically, the adsorption of AP on three rutile surfaces (1 1 0), (1 0 0), and (0 0 1), as well as two anatase surfaces (1 0 1), and (0 0 1) were modeled using cluster models, along with the decomposition of adsorbed AP into small molecules. The optimized complexes of the AP molecule on TiO2 surfaces were very stable, indicating strong covalent and hydrogen bonding interactions, leading to highly energetic adsorption reactions. The calculated energy of adsorption (ΔEads) ranged from -120.23 to -301.98 kJ/mol, with highly exergonic calculated Gibbs free energy (ΔGads) of reaction, and highly exothermic enthalpy of reaction (ΔHads). The decomposition of adsorbed AP was also found to have very negative ΔEdec values between -199.08 and -380.73 kJ/mol. The values of ΔGdec and ΔHdec reveal exergonic and exothermic reactions. The adsorption of AP on TiO2 surfaces anticipates the heat release of decomposition, in agreement with experimental results. The most common anatase surface, (1 0 1), was predicted to be more reactive for AP decomposition than the most stable rutile surface, (1 1 0), which was confirmed by experiments. DFT calculations show the mechanism for activation of the two TiO2 polymorphs is entropy driven.

Reliability-Based Design Optimization for Polymer Electrolyte Membrane Fuel Cells: Tackling Dimensional Uncertainties in Manufacturing and Their Effects on Costs of Cathode Gas Diffusion Layer and Bipolar Plates.

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) have emerged as a pivotal technology in the automotive industry, significantly contributing to the reduction of greenhouse gas emissions. However, the high material costs of the gas diffusion layer (GDL) and bipolar plate (BP) create a barrier for large scale commercial application. This study aims to address this challenge by optimizing the material and design of the cathode, GDL and BP. While deterministic design optimization (DDO) methods have been extensively studied, they often fall short when manufacturing uncertainties are introduced. This issue is addressed by introducing reliability-based design optimization (RBDO) to optimize four key PEMFC design variables, i.e., gas diffusion layer thickness, channel depth, channel width and land width. The objective is to maximize cell voltage considering the material cost of the cathode gas diffusion layer and cathode bipolar plate as reliability constraints. The results of the DDO show an increment in cell voltage of 31 mV, with a reliability of around 50% in material cost for both the cathode GDL and cathode BP. In contrast, the RBDO method provides a reliability of 95% for both components. Additionally, under a high level of uncertainty, the RBDO approach reduces the material cost of the cathode GDL by up to 12.25 $/stack, while the material cost for the cathode BP increases by up to 11.18 $/stack Under lower levels of manufacturing uncertainties, the RBDO method predicts a reduction in the material cost of the cathode GDL by up to 4.09 $/stack, with an increase in the material cost for the cathode BP by up to 6.71 $/stack, while maintaining a reliability of 95% for both components. These results demonstrate the effectiveness of the RBDO approach in achieving a reliable design under varying levels of manufacturing uncertainties.

Enhanced blebbing as a marker for metastatic prostate cancer.

Highly metastatic prostate cancer cells flowing through a microfluidic channel form plasma membrane blebs: they form 27% more than normal cells and have a lower stiffness (about 50%). Hypo-osmotic stress assays (with ∼ 50 % osmolarity) show 22% more blebbing of highly metastatic than moderately metastatic and 30% more than normal cells. Plasma membrane blebbing is known to provide important metastatic capabilities to cancer cells by aiding cell detachment from the primary tumor site and increasing cell deformability to promote cell migration through the extracellular matrix. Increased blebbing was attributed by others to decreased phosphorylated ezrin, radixin, and moesin (ERM) (p-ERM) protein expression-p-ERMs bind the plasma membrane to the actin cortex and reduced p-ERM expression can weaken membrane-cortex attachment. Myosin II also influences blebbing as myosin's natural contraction generates tension in the actin cortex. This increases cellular hydrostatic pressure, causes cortex rupture, cytoplasm flow out of the cortex, and hence blebbing. Highly metastatic cells are surprisingly found to express similar ezrin and myosin II levels but higher moesin levels in comparison with lowly metastatic or normal cells-suggesting that their levels, contrary to the literature [G. Charras and E. Paluch, Nat. Rev. Mol. Cell Biol. 9(9), 730-736 (2008); J.-Y. Tinevez, U. Schulze, G. Salbreux, J. Roensch, J.-F. Joanny, and E. Paluch, Proc. Natl. Acad. Sci. U.S.A. 106(44), 18581-18586 (2009); M. Bergert, S. D. Chandradoss, R. A. Desai, and E. Paluch, Proc. Natl. Acad. Sci. U.S.A. 109(36), 14434-14439 (2012); E. K. Paluch and E. Raz: Curr. Opin. Cell Biol. 25(5), 582-590 (2013)], are not important in metastatic prostate cell blebbing. Our results show that reduced F-actin is primarily responsible for increased blebbing in these metastatic cells. Blebbing can thus serve as a simple prognostic marker for the highly incident and lethal metastatic prostate cancer.