BiFACIAL (<i>Bi</i>omimetic <i>F</i>reestanding <i>A</i>nisotropic <i>C</i>atechol‑<i>I</i>nterfaces with <i>A</i>symmetrically <i>L</i>ayered) Films as Versatile Extracellular Matrix Substitutes

Biological naïve extracellular matrices (ECMs) exhibit anisotropic functions in their physical, chemical, and morphological properties. Representative examples include anisotropic skin layers or blood vessels simultaneously facing multiphasic environments. Here, anisotropically multifunctional structures called BiFACIAL (<i>bi</i>omimetic <i>f</i>reestanding <i>a</i>nisotropic <i>c</i>atechol-<i>i</i>nterfaces with <i>a</i>symmetrically <i>l</i>ayered) films were developed simply by contacting two polysaccharide solutions of heparin-catechol (Hep-C) and chitosan-catechol (Chi-C). Such anisotropic characters were due to controlling catechol cross-linking by alkaline pH, resulting in a trimodular structure: a rigid yet porous Hep-C exterior, nonporous interfacial zone, and soft/highly porous Chi-C interior. The anisotropic features of each layer, including the porosity, rigidity, rheology, composition, and ionic strength, caused the BiFACIAL films to show spontaneously biased stimuli responses and differential behaviors against biological substances (e.g., blood plasma). The films could be created in situ in live animals and imitated the structural/functional aspects of the representative anisotropic tissues (e.g., skin and blood vessels), providing valuable ECM-like platforms for the creation of favorable environments or for tissue regeneration or disease treatment by effectively manipulating cellular behaviors

Analysis of Recombination Losses in a Pentacene/C₆₀ Organic Bilayer Solar Cell

Transient photovoltage and charge extraction analyses are used to quantify the rate of nongeminate recombination loss within a pentacene/C₆₀ bilayer solar cell across the power-generating quadrant of the device. Employing these data, a simple model of cell function, based on field-independent generation and a charge-dependent nongeminate loss current without the use of any adjustable fitting parameters, is shown to be in good agreement with the experimental current/voltage behavior of the device both in the dark and under illumination

Characterization and Control of Nanoparticle Emission during 3D Printing

This study aimed to evaluate particle emission characteristics and to evaluate several control methods used to reduce particle emissions during three-dimensional (3D) printing. Experiments for particle characterization were conducted to measure particle number concentrations, emission rates, morphology, and chemical compositions under manufacturer-recommended and consistent-temperature conditions with seven different thermoplastic materials in an exposure chamber. Eight different combinations of the different control methods were tested, including an enclosure, an extruder suction fan, an enclosure ventilation fan, and several types of filter media. We classified the thermoplastic materials as high emitter (>10¹¹ #/min), medium emitters (10⁹ #/min −10¹¹ #/min), and low emitters (<10⁹ #/min) based on nanoparticle emissions. The nanoparticle emission rate was at least 1 order of magnitude higher for all seven filaments at the higher consistent extruder temperature than at the lower manufacturer-recommended temperature. Among the eight control methods tested, the enclosure with a high-efficiency particulate air (HEPA) filter had the highest removal effectiveness (99.95%) of nanoparticles. Our recommendations for reducing particle emissions include applying a low temperature, using low-emitting materials, and instituting control measures like using an enclosure around the printer in conjunction with an appropriate filter (e.g., HEPA filter) during 3D printing