Organogel Formation of Soybean Oil with Waxes

Many waxes including plant waxes and animal waxes were evaluated for the gelation ability toward soybean oil (SBO) and compared with hydrogenated vegetable oils, petroleum waxes and commercial non-edible gelling agents to understand factors affecting the gelation ability of a gelator. Sunflower wax (SW) showed the most promising results and all SW samples from three different suppliers could make a gel with concentrations as low as 0.5 wt%. Candelilla wax and rice bran wax also showed good gelation properties, which, however, varied with different suppliers. Gelation ability of a wax is significantly dependant on its purity and detailed composition. A wax ester with longer alkyl chains has significantly better gelation ability toward SBO than that with shorter alkyl chains indicating that the chain length of a component in a wax such as wax ester is an important factor for gelation ability. The SW–SBO organogel showed increased melting point with increased SW content, showing the melting point range from about 47 to 65 °C with 0.5–10 wt% SW. The effects of cooling rate on crystal size and firmness of a gel were investigated. The dependence of firmness on cooling rate was so significant that the desired texture of an organogel could be achieved by controlling the cooling rate in addition to controlling the amount of gelling agent. This research reveals that a small amount of food grade plant waxes including SW may replace a large amount of the hardstock containing trans-fat or saturated fat.     

Understanding Chemical Expansion in Non‐Stoichiometric Oxides: Ceria and Zirconia Case Studies

Atomic scale computer simulations, validated with experimental data, are used to uncover the factors responsible for defect‐induced chemical expansion observed in non‐stoichiometric oxides, exemplified by CeO₂ and ZrO₂. It is found that chemical expansion is the result of two competing processes: the formation of a vacancy (leading to a lattice contraction primarily due to electrostatic interactions) and the cation radius change (leading to a lattice expansion primarily due to steric effects). The chemical expansion coefficient is modeled as the summation of two terms that are proportional to the cation and oxygen radius change. This model introduces an empirical parameter, the vacancy radius, which can be reliably predicted from computer simulations, as well as from experimental data. This model is used to predict material compositions that minimize chemical expansion in fluorite structured solid oxide fuel cell electrolyte materials under typical operating conditions.     

Hole mobilities of thermally polymerized triaryldiamine derivatives and their application as hole-transport materials in organic light-emitting diodes (OLEDs)

This paper describes the synthesis of three triaryldiamine derivatives presenting two thermally polymerizable trifluorovinyl ether groups that can be polymerized through thermal curing to form perfluorocyclobutyl (PFCB) polymers. These PFCB polymers, studied using time-of-flight techniques for the first time, exhibited remarkable non-dispersive hole-transport properties, with values of μ_h of ca. 10^?4 cm² V^?1 s^?1. When we employed these thermally polymerized polymers as hole-transport layers (HTLs) in electroluminescence devices containing tris(8-hydroxyquinolate) aluminum (Alq₃) as the emission layer, we obtained high current densities (ca. 3400 mA cm^?2), impressive brightnesses (5 × 10⁴ cd m^?2), and high external quantum efficiencies (EQEs = 1.43%). These devices exhibited the same turn-on voltage, but higher EQEs, relative to those incorporating the vacuum-processed model compound N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (α-NPD) (EQE = 1.37%) as the HTL under the same device structure.     

Characterization of Pt/SiO2 Model Catalysts at UHV and Near Atmospheric Pressures

Pt/SiO₂ model catalyst samples, prepared under UHV conditions in a contiguous high pressure reactor cell surface analysis chamber, have been characterized via CO oxidation reaction kinetics under elevated pressure conditions (approaching 1 atm). Reaction kinetics are studied as a function of Pt coverage (θ _Pt = 1–10 mL), along with measurements on a Pt(110) single crystal for direct comparison. CO desorption measurements and STM measurements on Pt/SiO₂ films at T = 300 K have been obtained at various θ _Pt. Kinetic results show agreement between observations on single crystal and catalyst samples, and general agreement and correlation is obtained for site calculations across the various methods. Results demonstrate the utility of well characterized model catalyst samples in obtaining qualitative and quantitative reactivity data at elevated pressures.     

Use of an alteplase algorithm for the management of hemodialysis catheter dysfunction

Hemodialysis (HD) catheter dysfunction compromises HD adequacy and increases the cost of patient care. Repeated administration of alteplase in HD catheters typically produces only short-term benefits. The purpose of this study was to design, implement, and evaluate the efficacy of an experimental alteplase algorithm to manage HD catheter dysfunction. This was a two-part prospective nonrandomized study. Baseline data of alteplase use and catheter exchange were collected during part 1 of the study. Part 2 consisted of the alteplase algorithm implementation and repeat collection of catheter data. Rates of alteplase use and catheter exchange per 1000 catheter-days were the primary and secondary outcomes of the study. One hundred and seventy-two catheters in 131 patients were followed prospectively during the course of the study. The adjusted relative rate (RR) of alteplase use showed no significant difference between both parts of the study, adjusted RR: 1.10, 95% confidence interval (CI) (0.73-1.65). Similarly, catheter exchange rates were not significantly different over the duration of the study (1.12 vs. 1.03 per 1000 catheter-days). However, waiting time for catheter exchange increased from 20.36 ± 14 days in part 1 to 38.42 ± 28 days in part 2 (P < 0.05). The alteplase algorithm did not significantly reduce alteplase use. This may be partially explained by repeated use of alteplase in part 2, due to longer waiting times for catheter exchange procedures.     

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