Ashbyhedrick0893

The elucidation of complex electrochemical reaction mechanisms requires advanced models with many intermediate reaction steps, which are governed by a large number of parameters like reaction rate constants and charge transfer coefficients. Overcomplicated models introduce high uncertainty in the choice of the parameters and cannot be used to obtain meaningful insights on the reaction pathway. We describe a new framework of optimal reaction mechanism selection based on the mean-field microkinetic modeling approach (MF-MKM) and adaptive sampling of model parameters. The optimal model is selected to provide both the accurate fitting of experimental data within the experimental error and low uncertainty of model parameters choice. Generally, this approach can be applied for any complex heterogeneous electrochemical reaction. We use the "2e-" electrocatalytic oxygen reduction reaction (ORR) on carbon nanotubes (CNTs) as a representative example of a sufficiently complex reaction. Rotating disk electrode (RDE) experimental data for both ORR in O2-saturated 0.1 M KOH solution and hydrogen peroxide oxidation/reduction reaction (HPRR/HPOR) in Ar-purged 0.1 M KOH solution with different HO2- concentrations were used to show the dependence of the model parameters uniqueness on the completeness of the experimental dataset. It is demonstrated that the optimal reaction mechanism for ORR on CNT and available experimental data consists of O2 adsorption step on the electrode surface and effective step of two-electron reduction to HO2- combined with its desorption from the electrode. The low uncertainty of estimated model parameters is provided only within the 2-step model being applied to the full available experimental dataset. The assessment of elementary step mechanisms on electro-catalytic materials including carbon-based electrodes requires more diverse experimental data and/or higher precision of experimental measurements to facilitate more precise microkinetic modeling of more complex reaction mechanisms.The organization of multiple subcellular compartments is controlled by liquid-liquid phase separation. Phase separation of this type occurs with the emergence of interfacial tension. Aqueous two-phase systems formed by two non-ionic polymers can be used to separate and analyze biological macromolecules, cells and viruses. Phase separation in these systems may serve as the simple model of phase separation in cells also occurring in aqueous media. To better understand liquid-liquid phase separation mechanisms, interfacial tension was measured in aqueous two-phase systems formed by dextran and polyethylene glycol and by polyethylene glycol and sodium sulfate in the presence of different additives. Interfacial tension values depend on differences between the solvent properties of the coexisting phases, estimated experimentally by parameters representing dipole-dipole, ion-dipole, ion-ion, and hydrogen bonding interactions. Based on both current and literature data, we propose a mechanism for phase separation in aqueous two-phase systems. This mechanism is based on the fundamental role of intermolecular forces. Although it remains to be confirmed, it is possible that these may underlie all liquid-liquid phase separation processes in biology.The unique molecular balloon system of [Pd6L8](NO3)12 (an inner cavity of 19 × 21 × 25 Å3⇄ 13 × 13 × 13 Å3) was carried out via the anion exchange of nitrate with alkyl sulfates.We demonstrate the ability of two tripeptides to promote proliferation and modulate the mechanical properties of human mesenchymal stem cells (hMSCs). Notably, Young's modulus of peptide-treated hMSCs was found to be ∼2 fold higher compared to the control group. These peptides promoted wound healing in hMSCs, without stimulating osteogenic and adipogenic differentiation, thus showing high potential in vascular tissue engineering applications.The uncapped tripeptide DPhe-Phe-Leu acts as self-assembly template to yield supramolecular hydrogel biomaterials. As an example, self-assembling DPhe-Phe-Leu-Asp-Val contains the LDV bioadhesive motif for β1 integrin activation. Hydrogels made of the two peptides successfully mimic fibronectin of the extracellular matrix and lead to high cell viability, adhesion, and spreading.Nucleus-targeting NPs based on RuO2 (RuO2NPs) were developed by controlling the size and the surface charge of nanoparticles (NPs). This study not only demonstrates a facile approach for the fabrication of ultrasmall CS-RuO2NPs with good biocompatibility and excellent photothermal properties but also their unique potential for the nucleus-targeted low-temperature PTT.Both synthetic polymers (membranes, coatings, packaging) and natural polymers (DNA, proteins) are subject to radical-initiated degradation. In order to mitigate the deterioration of the polymer properties, antioxidant strategies need to be devised. We studied the reactions of poly(α-methylstyrene sulfonate), a model compound for fuel cell membrane materials, with different degrees of polymerization with OH˙ radicals as well as subsequent reactions. We observed the resulting OH˙-adducts to react with oxygen and eliminate H2O, the relative likelihood of which is determined by pH and molecular weight. The resulting radical cations can be reduced back to the parent molecule by cerium(iii). This 'repair' reaction is also dependent on molecular weight likely because of intramolecular stabilization. The results from this study provide a starting point for the development of new hydrocarbon-based ionomer materials for fuel cells that are more resistant to radical induced degradation through the detoxification of intermediates via damage transfer and repair pathways. Furthermore, a more fundamental understanding of the mechanisms behind conventional antioxidants in medicine, such as ceria nanoparticles, is achieved.We constructed a carbon-based polymer dot (CPD) sensor to detect breast cancer based on the differences of peripheral blood cells, providing a new minimally invasive method for cancer diagnosis. This simple and extensible system exhibits clinically relevant accuracy in terms of cancer identification, making it an attractive strategy for diagnosis and prognosis.This is the first direct observation that surface proton hopping occurs on SrZrO3 perovskite even under a H2 (i.e. dry) atmosphere. Understanding proton conduction mechanisms on ceramic surfaces under a H2 atmosphere is necessary to investigate the role of proton hopping on the surface of heterogeneous catalysts in an electric field. In this work, surface protonics was investigated using electrochemical impedance spectroscopy (EIS). To extract the surface proton conduction, two pellets of different relative densities were prepared a porous sample (R.D. = 60%) and a dense sample (R.D. Etomoxir ic50 = 90%). Comparison of conductivities with and without H2 revealed that only the porous sample showed a decrease in the apparent activation energy of conductivity by supplying H2. H/D isotope exchange tests revealed that the surface proton is the dominant conductive species over the porous sample with H2 supply. Such identification of a dominant conductive carrier facilitates consideration of the role of surface protonics in chemical reactions.We present a new strategy for the fabrication of nanoporous polymer films assembled using strong polyelectrolyte pairs in ionic liquid aqueous solutions. These nanoporous films show good anti-reflection properties.It is strongly desired to develop highly active photocatalysts for CO2 reduction by accelerating charge separation and realizing spatially separated active sites. In this work, Ti2O3/TiO2 heterophase junctions with enhanced charge separation and spatially separated active sites were facilely prepared via in situ thermal oxidation of commercial Ti2O3 in air at an appropriate annealing temperature. The as-prepared Ti2O3/TiO2 heterophase junctions, especially the temperature-optimized T550 sample, displayed high photocatalytic activity for CO2 reduction to yield CH4 (∼0.65 μmol g-1 h-1), CO (∼2.64 μmol g-1 h-1) and O2 (∼5.66 μmol g-1 h-1), which was 4 times higher than that of bulk Ti2O3 and nearly 2 times higher than that of rutile TiO2. Based on the surface photovoltage spectra, related produced OH radical measurement and electrochemical reduction, the high photoactivity could be attributed to the metallic Ti2O3, which trapped the photogenerated electrons from TiO2 through the formed Ti2O3/TiO2 heterophase junctions to enhance charge separation. Remarkably, it was confirmed from theoretical calculations based on density functional theory, Kelvin probe and CO2-TPD measurements that the Ti2O3/TiO2 heterophase junction possesses spatially separated active sites for CO2 reduction and water oxidation. Metallic Ti2O3 as a reduction site activated and catalyzed CO2 to produce solar fuels such as CO and CH4, while TiO2 as an oxidation site oxidized H2O to produce O2 and protons. The designed concept of heterophase junctions and simultaneously activating CO2 and H2O at different spatial sites may offer a new strategy to suppress the reverse reactions during photocatalysis for efficient solar energy conversion.An efficient novel visible-light photoredox-catalyzed dual carbon-carbon bond cleavage of methylenecyclopropanes and cycloketone oximes for the synthesis of 2-cyanoalkylsulfonated 3,4-dihydronaphthalenes through the insertion of sulfur dioxide is established. This dual cleavage of carbon-carbon bonds involves a radical pathway and goes through a sequence of iminyl radical formation, carbon-carbon bond cleavage, sulfur dioxide insertion, sulfonyl radical addition, another carbon-carbon bond cleavage, and intramolecular cyclization.A novel micro-mesoporous nanofilm-constructed macroscopic macroporous titanosilicate (MNCMM-TiSi) has been successfully prepared by a templating approach. The resultant materials exhibit greatly improved TOFs in bulky alkene epoxidation compared to the conventional TS-1 zeolite and Ti-MCM-41.Detection of metabolic activity in living cells facilitates the understanding of the cell mechanism. Here, we report a fluorescent probe that can detect fatty acid beta oxidation (FAO) in living cells. This probe is metabolically degraded by the sequential enzyme reactions of FAO and can visualize the FAO activity with turn-on fluorescence.N-Doped carbon nanotubes with embedded cobalt nanoparticles (Co-NCNTs) were prepared by thermally annealing a mixture of ZIF-67 and dicyandiamide precursors. Because of the dual chemical affinity of Co and N to S species, Li-S batteries with a Co-NCNT modified separator revealed enhanced redox kinetics of lithium polysulfide conversion and achieved a high areal capacity of 3.73 mA h cm-2 after 100 cycles at 0.1C at a sulfur loading of 4.3 mg cm-2.We report synthesis and enzymatic assays on human histone lysine methyltransferase catalysed methylation of histones that possess lysine and its geometrically constrained analogues containing rigid (E)-alkene (KE), (Z)-alkene (KZ) and alkyne (Kyne) moieties. Methyltransferases G9a and GLP do have a capacity to catalyse methylation in the order K ≫ KE > KZ ∼ Kyne, whereas monomethyltransferase SETD8 catalyses only methylation of K and KE.