Crystal size effect is of vital importance in materials science by exerting significant influence on various properties of materials and furthermore their functions. Crystal size effect of covalent organic frameworks (COFs) has never been reported because their controllable synthesis is difficult, despite their promising properties have been exhibited in many aspects. Here, we report the diverse crystal size effects of two representative COFs based on the successful realization of crystal-size-controlled synthesis. For LZU-111 with rigid spiral channels, size effect reflects in pore surface area by influencing the pore integrity, while for flexible COF-300 with straight channels, crystal size controls structural flexibility by altering the number of repeating units, which eventually changes sorption selectivity. With the understanding and insight of the structure-property correlation not only at microscale but also at mesoscale for COFs, this research will push the COF field step forward to a significant advancement in practical applications.

We demonstrate herein a facile approach for constructing -C[double bond, length as m-dash]N- linked COFs from acetals. Three new COFs (imine-linked LZU-20, hydrazone-linked LZU-21, and azine-linked LZU-22) were synthesized by the direct condensation of dimethyl acetals and amines. All the synthesized COFs are highly crystalline and exhibit good thermal stability.

Core collections are representative subsamples of germplasm collections. Use of core collections may improve the efficiency of germplasm evaluations by reducing the number of accessions evaluated while increasing the probability of finding genes of interest. The peanut (Arachis hypogaea L.) core collection has been examined for resistance to the peanut root‐knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1]. Resistant indicator accessions from screening the core collection identified 39 clusters in the entire germplasm collection that should be examined more thoroughly. The objective of this study was to evaluate how effective a two‐stage core screening approach would be in identifying resistance to M. arenaria in the entire U.S. germplasm collection of peanut. Accessions from 30 clusters having resistant indicator accessions and from four clusters having very susceptible indicator accessions were tested for resistance in two greenhouse trials. This second stage screening identified 259 accessions that had a mean egg‐mass rating of 2.5 or less. Twenty‐eight of these accessions had a mean egg‐mass rating of 1.0 or less. There were relatively large numbers of resistant accessions from China and Japan compared with the percentages of the germplasm collection that originated from these countries. The efficiency of identifying accessions resistant to M. arenaria was greater in clusters having resistant indicator accessions than in clusters having susceptible indicator accessions. These results demonstrate that the use of a two‐stage screening approach with a core collection can improve the efficiency of identifying valuable genes in germplasm collections.

Compared with standard cultivars, seed of mid-oleic soybean genotypes sometimes have shown increased colonization by Cercospora kikuchii in the field as judged by increased levels of purple-stained seed. To examine relationships between oleic and linoleic acid levels in soybean seed and postharvest seed colonization by two fungal seed pathogens, we inoculated seed with differing oleic:linoleic acid (O/L) ratios. Seed with defined O/L ratios were produced by allowing seed development of two isogenic soybean lines to occur in three different air temperature environments. Seed produced in these environments were harvested, individually analyzed for fatty acid composition, and inoculated with mycelium preparations of the fungal seed pathogens C. kikuchii or Diaporthe phaseolorum var. sojae. Fungal biomass of infected seed was quantified by measuring in vitro ergosterol content. For both soybean lines, colonization by C. kikuchii was positively correlated with the O/L ratio (r = 0.55, P < 0.03) and oleic acid content (r = 0.61, P < 0.02), and negatively correlated with linoleic (r = –0.60, P < 0.02) and linolenic (r = –0.58, P < 0.03) acid content. No association was found between the extent of seed colonization by D. phaseolorum and the seed O/L ratio. Our data suggest that the O/L ratio may be related to soybean seed colonization by C. kikuchii, but there is no evidence of a relationship with D. phaseolorum var. sojae colonization.

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The effect of the high-oleate trait of peanut on aflatoxin production was tested by comparing normal oleic lines with high-oleic backcross-derived lines. Seeds were blanched, quartered, and inoculated with Aspergillus flavus conidia, placed on moistened filter paper in petri dishes, and incubated for 8 days. In one experiment, dishes were stacked in plastic bags in a Latin square design with bags and positions in stacks as blocking variables. High-oleic lines averaged nearly twice as much aflatoxin as normal lines. Background genotype had no significant effect on aflatoxin content, and interaction between background genotype and oleate level was not detected. In a second experiment, dishes were arranged on plastic trays enclosed in plastic bags and stacked with PVC spacers between trays. Fungal growth and aflatoxin production were greater than in the first experiment. Background genotype, oleate level, and their interaction were significant. The mean of high-oleic lines was almost twice that of normal lines, but the magnitude of the difference varied with background genotype. Special care should be taken with high-oleic lines to prevent growth of Aspergillus spp. and concomitant development of aflatoxin contamination.

Telechelic polymers that contain a central polymer chain and two metal complex terminals would represent a novel class of functional metallopolymers. In this work, a series of telechelic polystyrenes end-difunctionalized...

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