One‐Pot Synthesis of Dealloyed AuNi Nanodendrite as a Bifunctional Electrocatalyst for Oxygen Reduction and Borohydride Oxidation Reaction

A novel one‐pot approach for synthesizing the dealloyed nanomaterials at room temperature is introduced for the first time. In such a synthetic strategy, applying modulated potentials effectively simplifies the traditional dealloying route, which usually requires additional corrosion process to dissolve nonprecious metals. The dealloyed AuNi nanodendrites (AuNi NDs) with tunable composition and uniformly elemental distribution are well developed by the one‐pot strategy. Impressively, the as‐synthesized AuNi NDs exhibit a higher electrochemically active area and definite improvements in electrocatalytic activity for oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) compared to the commercial Pt/C. In particular, the AuNi NDs are 81 mV more positive in half‐wave potential and about 3.1 times higher in specific activity (at 0.85 V) for the ORR than Pt/C, together with excellent stability and methanol tolerance. The superior BOR activity is highly promising compared to the previously reported catalysts. The unique nanodendritic structure with Au‐rich surface and bimetallic electronic effect is the main factor to greatly enhance the bifunctional catalytic performance for the AuNi NDs. Furthermore, such a newly developed facile method is of great significance because it is one of the first examples to effectively engineer dealloyed bimetallic nanostructures via the practical and low‐cost route for electrocatalytic applications.     

Selecting and assessing challenge problems

Abstract

Organisations conducting research programs often focus the work of their scientists and technologists on challenge problems (CPs). These challenges are designed to ensure that progress is measurable and relevant to the goals of the program sponsor. Generating and selecting pertinent CPs is difficult, as is assessing their value. We describe a method of generating and selecting CPs and its application in a highly collaborative, multi-organisation research program. Thirty-eight biologists, chemists, mathematicians and computer scientists across academic, commercial and government organisations generated and ranked their top choices from among 12 richly described candidate challenge problems. A ranked-choice voting formula was applied. Five CPs were highly scored; the remaining seven were distributed across a lower range of scores. The program sponsor subsequently directed researchers to address six CPs, including the elected five. Analysis of the rationales that participants offered for their CP rankings revealed four domain-independent dimensions of value: capability, speed, impact and synergy. These dimensions of value can help managers of interdisciplinary research programs systematically select a portfolio of CPs that will efficiently apply utilise resources towards program goals and facilitate measurement of scientific progress.     

Examining the Signaling Effect of E-tailers’ Return Policies

E-tailers normally have more accurate information regarding their products and services than consumers due to the nature of online transactions. To reduce consumers’ concerns of hidden information, e-tailers can use lenient return policies to attempt to signal high product and service quality. This research proposes a model to investigate the signaling effect of two components of return policy, return window—short return window vs. long return window and return depth—full refund vs. partial refund, on product quality and service quality. Data was collected using an online survey and analyzed using structural equation modeling. The results show that both a long return window and a full refund signal high service quality, which then positively affects purchase intention. When it comes to product quality, return window does not have a signaling effect, while the signaling effect of return depth is moderated by service quality.     

The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin

Cholesterol seems to play a central role in the augmentation of saporin-based immunotoxin (IT) cytotoxicity by triterpenoid saponins. Endolysosomal escape has been proposed as one mechanism for the saponin-mediated enhancement of targeted toxins. We investigated the effects of lipid depletion followed by repletion on Saponinum album (SA)-induced endolysosomal escape of Alexa Fluor labelled saporin and the saporin-based immunotoxin OKT10-SAP, directed against CD38, in Daudi lymphoma cells. Lipid deprived cells showed reduced SA-induced endolysosomal escape at two concentrations of SA, as determined by a flow cytometric method. The repletion of membrane cholesterol by low density lipoprotein (LDL) restored SA-induced endolysosomal escape at a concentration of 5 µg/mL SA but not at 1 µg/mL SA. When LDL was used to restore the cholesterol levels in lipid deprived cells, the SA augmentation of OKT10-SAP cytotoxicity was partially restored at 1 µg/mL SA and fully restored at 5 µg/mL SA. These results suggest that different mechanisms of action might be involved for the two different concentrations of SA and that endosomal escape may not be the main mechanism for the augmentation of saporin IT cytotoxicity by SA at the sub-lytic concentration of 1 µg/mL SA.     

Macro- and microscale variables regulate stent haemodynamics,fibrin deposition and thrombomodulin expression

Drug eluting stents are associated with late stent thrombosis (LST), delayed healing and prolonged exposure of stent struts to blood flow. Using macroscale disturbed and undisturbed fluid flow waveforms, we numerically and experimentally determined the effects of microscale model strut geometries upon the generation of prothrombotic conditions that are mediated by flow perturbations. Rectangular cross-sectional stent strut geometries of varying heights and corresponding streamlined versions were studied in the presence of disturbed and undisturbed bulk fluid flow. Numerical simulations and particle flow visualization experiments demonstrated that the interaction of bulk fluid flow and stent struts regulated the generation, size and dynamics of the peristrut flow recirculation zones. In the absence of endothelial cells, deposition of thrombin-generated fibrin occurred primarily in the recirculation zones. When endothelium was present, peristrut expression of anticoagulant thrombomodulin (TM) was dependent on strut height and geometry. Thinner and streamlined strut geometries reduced peristrut flow recirculation zones decreasing prothrombotic fibrin deposition and increasing endothelial anticoagulant TM expression. The studies define physical and functional consequences of macro- and microscale variables that relate to thrombogenicity associated with the most current stent designs, and particularly to LST.     

An absolute interval scale of order for point patterns

Human observers readily make judgements about the degree of order in planar arrangements of points (point patterns). Here, based on pairwise ranking of 20 point patterns by degree of order, we have been able to show that judgements of order are highly consistent across individuals and the dimension of order has an interval scale structure spanning roughly 10 just-notable-differences (jnd) between disorder and order. We describe a geometric algorithm that estimates order to an accuracy of half a jnd by quantifying the variability of the size and shape of spaces between points. The algorithm is 70% more accurate than the best available measures. By anchoring the output of the algorithm so that Poisson point processes score on average 0, perfect lattices score 10 and unit steps correspond closely to jnds, we construct an absolute interval scale of order. We demonstrate its utility in biology by using this scale to quantify order during the development of the pattern of bristles on the dorsal thorax of the fruit fly.     

Differential effects of air conditioning type on residential endotoxin levels in a semi‐arid climate

Residential endotoxin exposure is associated with protective and pathogenic health outcomes. Evaporative coolers, an energy‐efficient type of air conditioner used in dry climates, are a potential source of indoor endotoxins; however, this association is largely unstudied. We collected settled dust biannually from four locations in homes with evaporative coolers (n=18) and central air conditioners (n=22) in Utah County, Utah (USA), during winter (Jan‐Apr) and summer (Aug‐Sept), 2014. Dust samples (n=281) were analyzed by the Limulus amebocyte lysate test. Housing factors were measured by survey, and indoor temperature and relative humidity measures were collected during both seasons. Endotoxin concentrations (EU/mg) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons. Endotoxin surface loads (EU/m²) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons and in upholstered furniture during winter. For the nine significant season‐by‐location comparisons, EU/mg and EU/m² were approximately three to six times greater in homes using evaporative coolers. A plausible explanation for these findings is that evaporative coolers serve as a reservoir and distribution system for Gram‐negative bacteria or their cell wall components in homes.     

Analysis of variance in capillary rheometry

The effect of deformation history (hysteresis) on transient capillary rheometric data was studied compared to conventional assumptions regarding steady state data. The factors studied were: the position instrumentation, the pressure instrumentation, entrance and exit effects, polymer melt compressibility, pressure dependence of the viscosity, and polymer melt viscous heating. Statistical analysis of variance was performed to statistically determine the sources of variance to specific degrees of confidence. The polymer melt compressibility, pressure dependence, and viscous heating were found to be statistically significant contributors of the observed variation at the 95% confidence level; the capillary length and instrumentation were not found to be significant. The results indicate that the transient behavior can vary the modeling of the apparent viscosity in a significant manner such that the model fidelity and model coefficients may vary substantially. Hence, polymer melt compressibility, pressure dependence, and viscous heating should be considered during rheological model fitting to increase model fidelity and predictive accuracy in end‐use. POLYM. ENG. SCI., 56:895–904, 2016. © 2016 Society of Plastics Engineers     

Physical filtration efficiency analysis of a polyaniline hybrid composite filter with graphite oxide for particulate matter 2.5

Particulate matter (PM) 2.5 pollution is a prevalent environmental and public health issue that has raised serious global concerns. Because standard heating, ventilation, and air conditioning filters are incapable of filtering out PM 2.5 particles efficiently, different methods of PM 2.5 filtration, such as physical filtration and electrostatic filtration, are under investigation to develop a filter with a high filtration efficiency and a low pressure drop. According to various studies, pressure drop has a significant influence on the filtration efficiency. An equation for the theoretical trend was generated based on the composite data gathered from similar filtration studies and was used to evaluate the relationship between pressure drop and filtration efficiency. Here, the theoretical equation indicated that the filtration efficiency increased as the pressure drop on a filter increased until 0.01 psi where the efficiency remained near constant at approximately 99.9%. In this study, we introduce a graphite oxide (GO) and polyaniline (PANi) composite hybrid filter in order to create a low-pressure (1.2 psi) drop filter. By adding GO flakes to the PANi matrix, we not only produced a highly permeable filter while allowing continuous gas flow, but also achieved a remarkable and highly effective PM 2.5 filter with a filtration efficiency of 99.7 ± 0.08%.