Exacerbation of allergic inflammation in mice exposed to diesel exhaust particles prior to viral infection

Background  

Viral infections and exposure to oxidant air pollutants are two of the most important inducers of asthma exacerbation. Our previous studies have demonstrated that exposure to diesel exhaust increases the susceptibility to influenza virus infections both in epithelial cells in vitro and in mice in vivo. Therefore, we examined whether in the setting of allergic asthma, exposure to oxidant air pollutants enhances the susceptibility to respiratory virus infections, which in turn leads to increased virus-induced exacerbation of asthma. Ovalbumin-sensitized (OVA) male C57BL/6 mice were instilled with diesel exhaust particles (DEP) or saline and 24 hours later infected with influenza A/PR/8. Animals were sacrificed 24 hours post-infection and analyzed for markers of lung injury, allergic inflammation, and pro-inflammatory cytokine production.     

Understanding the Role of Underlayers and Overlayers in Thin Film Hematite Photoanodes

Recent research on photoanodes for photoelectrochemical water splitting has introduced the concept of under‐ and overlayers for the activation of ultrathin hematite films. Their effects on the photocatalytic behavior were clearly shown; however, the mechanism is thus far not fully understood. Herein, the contribution of each layer is analyzed by means of electrochemical impedance spectroscopy, with the aim of obtaining a general understanding of surface and interface modifications and their influence on the hematite photoanode performance. This study shows that doping of the hematite from the underlayer and surface passivation from annealing treatments and an overlayer are key parameters to consider for the design of more efficient iron oxide electrodes. Understanding the contribution of these layers, a new design for ultrathin hematite films employing a combination of a gallium oxide overlayer with thin niobium oxide and silicon oxide underlayers is shown to achieve a photocurrent onset potential for the photoelectrochemical oxidation of water more negative than 750 mV versus the reversible hydrogen electrode (RHE) at pH 13.6, utilizing Co‐Pi as a water oxidation catalyst. It is demonstrated that multilayer hematite thin film photoanodes are a strategy to reduce the overpotential for this material, thereby facilitating more efficient tandem cells.     

Ruthenium Oxide Hydrogen Evolution Catalysis on Composite Cuprous Oxide Water‐Splitting Photocathodes

Photocathodes based on cuprous oxide (Cu₂O) are promising materials for large scale and widespread solar fuel generation due to the abundance of copper, suitable bandgap, and favorable band alignments for reducing water and carbon dioxide. A protective overlayer is required to stabilize the Cu₂O in aqueous media under illumination, and the interface between this overlayer and the catalyst nanoparticles was previously identified as a key source of instability. Here, the properties of the protective titanium dioxide overlayer of composite cuprous oxide photocathodes are further investigated, as well as an oxide‐based hydrogen evolution catalyst, ruthenium oxide (RuO₂). The RuO₂‐catalyzed photoelectrodes exhibit much improved stability versus platinum nanoparticles, with 94% stability after 8 h of light‐chopping chronoamperometry. Faradaic efficiencies of ～100% are obtained as determined by measurement of the evolved hydrogen gas. The sustained photocurrents of close to 5 mA cm^?2 obtained with this electrode during the chronoamperometry measurement (at 0 V vs. the reversible hydrogen electrode, pH 5, and simulated 1 sun illumination) would correspond to greater than 6% solar‐to‐hydrogen conversion efficiency in a tandem photoelectrochemical cell, where the bias is provided by a photovoltaic device such as a dye‐sensitized solar cell.     

On thermal resistance in concentric residential geothermal heat exchangers

Residential geothermal ground-source heat pumps have been used for nearly 30 years as a low-cost, environmentally friendly alternative to traditional fossil-fuel systems. However, the limitation on a wider range of acceptance of the technology is the cost of the installation of a piping network through which the energy is transferred between the soil and the coolant. This cost is proportional to the piping length. We formulate a new mathematical modeling framework that calculates a characteristic streamwise length based on the geometry of the system, the operating conditions, and the material properties of the system materials and effective properties of the surrounding soil using a vertical concentric geothermal heat exchanger as an example. These concentric systems consist of a core flow (from the residence), which flows from the ground surface to the base of the well, and an annular return region in which the heat exchange between the fluid and the soil is expected to take place. Two modeling scenarios are considered: steady-state temperature profiles in the annular fluid region if the radial thermal resistance between the fluid and soil is fixed; a quasi-steady fluid temperature that captures the radial heat transfer from the fluid to the soil. For the first case, we find that the characteristic length is determined by the smallest eigenvalue of the separable thermal problem, where the velocity profile is laminar and there is no thermal transport between the core and the fluid. When this core-annular heat transfer is possible, the eigenvalue problem no longer satisfies the conditions for Sturm–Liouville theory, and through direct computation we find that energy transferred from the annular flow to the core reduces the temperature change. In the second case, we find that the temperature change is reduced over time, as the soil temperature near the exchanger responds to the energy transport. In both cases, the best thermal transport takes place when the annular gap is small. The impact of these results on system design considerations is discussed.     

FireCube: A multi-view localization framework for 3D fire analysis

Effective response to fire requires accurate and timely information of its evolution. In order to accomplish this valuable fire analysis step, this work fuses low-cost video fire detection results of multiple cameras using a novel multi-view localization framework. As such, valuable fire characteristics are detected at the early stage of the fire. The framework merges the single-view detection results of the multiple cameras by homographic projection onto multiple horizontal and vertical planes, which slice the scene. The crossings of these slices create a 3D grid of virtual sensor points, called the FireCube. Using this grid and subsequent spatial and temporal 3D clean-up filters, information about the location of the fire, its size and its direction of propagation can be instantly extracted from the video data. The novel aspect in the proposed framework is the 3D grid creation, which is a 3D extension of multiple plane homography. Also the use of spatial and temporal 3D filters, which extend existing 2D filter concepts, provides a more reliable fire analysis. Experimental results indicate that the proposed multi-view fire localization framework is able to accurately detect and localize the fire. Two cameras are already sufficient to achieve a dimension accuracy of 90% and a position accuracy of 98%. By further increasing the number of cameras it is even possible to achieve a dimension accuracy of 96% and a position accuracy of 99%. Furthermore, the experiments show that increasing the number of cameras to monitor the scene has a positive effect on the detection rate. The gain of using four cameras instead of one is 3%.     

Carbosilane Dendrimers as Nanoscopic Building Blocks for Hybrid Organic–Inorganic Materials and Catalyst Supports

Advanced nanoarchitectures can be achieved by covalent linking of dendrimeric modules into porous networks using sol–gel chemistry. The focus of this work lies in the conversion of second, third, and fourth generation carbosilane dendrimers to high surface area xerogels and aerogels, and the use of these materials as catalyst supports. By varying the hydrolysis solvent and dendrimeric precursor employed, the properties of the nanoarchitectures can be easily tuned. In particular, triethoxysilyl‐terminated dendrimers have been hydrolyzed in solvents of varying polarity with acid catalysts to produce micro‐ and mesoporous hybrid dendrimer xerogels and aerogels with a controllable degree of Si–OH functionality.