Generation and sampling of nanoscale infectious viral aerosols

<p>Airborne viruses represent a potentially significant health threat. However, only recently have researchers begun to characterize the size and infectivity of viral bioaerosols in the nanoscale size range. There are limitations in the generation of test viral aerosols and the ability to sample with acceptable efficiency. Reported here is use of a laminar-flow water condensation method to efficiently sample nanoscale bioaerosols to sizes well below 100 nm. We used MS2 bacteriophage in water to provide an aerosol with particles sizes from 300 nm down to 45 nm for sampling by both an all-glass impinger (4 mm; AGI-4) and the water condensation bioaerosol sampler. We demonstrated the existence of infectious viral particles below 100 nm and a higher collection efficiency by the water condensation sampler compared to the AGI-4 at nanoscale sizes. For example, the water condensation bioaerosol sampler that collected particles at 45 nm in diameter had 20 times more infective virions per collected particle compared to the AGI-4. However, when we corrected the AGI-4 data for particle size–dependent collection efficiency, the results were similar. We also used quantitative reverse transcription polymerase chain reaction, along with culturing for infectivity to determine the percent infectivity of the aerosol by particle size. Finally, we used a simple calculation to determine that a large fraction of sub-100 nm particles did not contain infectious virus because of the low titer concentration of virus in the Collison fluid.</p> <p>© 2016 RTI International</p

Facile Conversion of Hydroxy Double Salts to Metal–Organic Frameworks Using Metal Oxide Particles and Atomic Layer Deposition Thin-Film Templates

Rapid room-temperature synthesis of metal–organic frameworks (MOFs) is highly desired for industrial implementation and commercialization. Here we find that a (Zn,Cu) hydroxy double salt (HDS) intermediate formed <i>in situ</i> from ZnO particles or thin films enables rapid growth (<1 min) of HKUST-1 (Cu₃(BTC)₂) at room temperature. The space-time-yield reaches >3 × 10⁴ kg·m^–3·d^–1, at least 1 order of magnitude greater than any prior report. The high anion exchange rate of (Zn,Cu) hydroxy nitrate HDS drives the ultrafast MOF formation. Similarly, we obtained Cu-BDC, ZIF-8, and IRMOF-3 structures from HDSs, demonstrating synthetic generality. Using ZnO thin films deposited via atomic layer deposition, MOF patterns are obtained on pre-patterned surfaces, and dense HKUST-1 coatings are grown onto various form factors, including polymer spheres, silicon wafers, and fibers. Breakthrough tests show that the MOF-functionalized fibers have high adsorption capacity for toxic gases. This rapid synthesis route is also promising for new MOF-based composite materials and applications