Modeling Particle Penetrations Through Wall Assemblies Using Computational Fluid Dynamics

<div><p>Outdoor particles can penetrate through wall assemblies and influence the indoor air quality (IAQ). In this study, a computational fluid dynamics (CFD) model was developed for predicting the particle penetration through wood-framed residential wall assemblies. The model included a simplified approach to account for the particle loss due to the fiberglass insulation material layer in the wall assemblies. Particles ranging from 0.001 to 10 μm in diameter were studied. Particle movement was modeled following an Eulerian approach, while particle deposition in the fiberglass insulation was accounted for by an additional sink term in the governing equation, derived from the classical filtration theory. The model was applied to a typical residential wall assembly, assuming crack heights of 1 mm in the vertical direction and 3 mm in the horizontal direction and a fiberglass insulation width of 0.14 m. The results showed that 0.05–1 <i>μ</i>m particles were the most penetrable particles. The fiberglass insulation media reduced the particle penetration by more than 85% when the air permeability of the fiberglass insulation was larger than 0.001 s.</p><p>Copyright 2015 American Association for Aerosol Research</p></div

Highly Efficient and Stable Bimetallic AuPd over La-Doped Ca–Mg–Al Layered Double Hydroxide for Base-Free Aerobic Oxidation of 5‑Hydroxymethylfurfural in Water

As a promising renewable alternative to the production of petroleum-derived chemicals and energy, biomass transformation is attracting increasing attention in terms of green chemical processes and sustainable development. Specifically, selective aerobic oxidation of cellulose-derived 5-hydroxymethylfurfural (HMF) into high value-added 2,5-furandicarboxylic acid (FDCA) is regarded as one of the most attractive biomass transformations due to a wide range of its application prospects. Herein, we report the synthesis of a highly efficient and stable bimetallic AuPd nanocatalyst over the La-doped Ca–Mg–Al layered double hydroxide (La-CaMgAl-LDH) support for base-free aerobic oxidation of HMF to FDCA in water, which makes the biomass-based chemical process green and cost effective. Under optimized reaction conditions, the yield of FDCA can reach above 99%. Such encouraging performance of the catalyst is believed to be correlated with both the higher surface basicity of La-CaMgAl-LDH support and the synergy between Au–Pd atoms in the bimetallic AuPd nanoparticles, which can greatly favor the activation of reactants and reaction intermediates in the course of tandem oxidation reactions. The present work provides an effective strategy for developing highly efficient bimetallic catalysts with the enhanced stability by adjusting surface structures and compositions of supports for a wide range of base-free aerobic oxidation of other biomass-derived compounds in water

Highly Efficient Solar Cells Based on the Copolymer of Benzodithiophene and Thienopyrroledione with Solvent Annealing

Highly efficient PBDTTPD-based photovoltaic devices with the configuration of ITO/poly­(3,4-ethylenedioxythiophene)-poly­(styrenesulfonate) (PEDOT:PSS)/PBDTTPD: methanofullerene (6,6)-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) (weight ratio being from 1:1 to 1:4)/LiF (5 Å)/Al (100 nm), were realized with ortho-dichlorobenzene (DCB) solvent annealing treatment. It was revealed that the best photovoltaic device was obtained when the blend ratio of PBDTTPD:PC₆₁BM was modulated to be 1:2 and processed with DCB solvent annealing for 12 h. The short-circuit current density (<i>J</i>_sc) and power conversion efficiency (PCE) values were measured to be 10.52 mA/cm² and 4.99% respectively, which were both higher than the counterparts treated with chlorobenzene (CB) solvent annealing or the thermal annealing. Atomic force microscopy measurements of the active layer after solvent annealing treatment were also carried out. The phase separation length scale of the PBDTTPD:PC₆₁BM­(1:2) layer was comparable to the exciton diffusion length when the active layer was treated under DCB solvent annealing, which facilitated effective exciton dissociation and carrier diffusion in the active layer. Therefore, highly efficient PBDTTPD-based photovoltaic devices could be achieved with DCB solvent annealing, which indicated that solvent annealing with proper solvent might be an easily processed, low-cost, and room-temperature alternative to thermal annealing for polymer solar cells