Covalent organic frameworks (COFs), in which molecular building blocks form robust microporous networks, are usually synthesized as insoluble and unprocessable powders. We have grown two-dimensional (2D) COF films on single-layer graphene (SLG) under operationally simple solvothermal conditions. The layered films stack normal to the SLG surface and show improved crystallinity compared with COF powders. We used SLG surfaces supported on copper, silicon carbide, and transparent fused silica (SiO₂) substrates, enabling optical spectroscopy of COFs in transmission mode. Three chemically distinct COF films grown on SLG exhibit similar vertical alignment and long-range order, and two of these are of interest for organic electronic devices for which thin-film formation is a prerequisite for characterizing their optoelectronic properties.

Less than 10% of the estimated average requirement (EAR) for iron and zinc is provided by consumption of storage roots of the staple crop cassava (Manihot esculenta Crantz) in West African human populations. We used genetic engineering to improve mineral micronutrient concentrations in cassava. Overexpression of the Arabidopsis thaliana vacuolar iron transporter VIT1 in cassava accumulated three- to seven-times-higher levels of iron in transgenic storage roots than nontransgenic controls in confined field trials in Puerto Rico. Plants engineered to coexpress a mutated A. thaliana iron transporter (IRT1) and A. thaliana ferritin (FER1) accumulated iron levels 7–18 times higher and zinc levels 3–10 times higher than those in nontransgenic controls in the field. Growth parameters and storage-root yields were unaffected by transgenic fortification in our field data. Measures of retention and bioaccessibility of iron and zinc in processed transgenic cassava indicated that IRT1 + FER1 plants could provide 40–50% of the EAR for iron and 60–70% of the EAR for zinc in 1- to 6-year-old children and nonlactating, nonpregnant West African women.

Using real-time x-ray scattering to measure the surface morphology of Au(111) during sputter erosion with 500 eV ${\mathrm{Ar}}^{+}$ ions, we observe three distinct regimes: three-dimensional rough erosion at 20– $60°\mathrm{C}$, quasi-layer-by-layer removal at 120– $220°\mathrm{C}$, and step retraction above $270°\mathrm{C}$. Sputtering at 20– $60°\mathrm{C}$ leads to pattern formation with a characteristic spacing between features. The average separation $l$ between features increases with time $t$, consistent with a power law $l\sim t^{0.27\pm 0.02}$. The observations are consistent with the predictions of a continuum model for deposition which includes an Ehrlich-Schwoebel barrier to the interlayer diffusion of surface defects.