[reaction: see text] A series of carbazole/fluorene (CBZm-Fn) hybrids were effectively synthesized through Friedel-Crafts-type substitution of the carbazole rings. These compounds were thermally and morphologically stable host materials for OLED applications. Efficient blue phosphorescent OLEDs were obtained when employing CBZ1-F2 as the host and FIrpic as the guest.

Genetic analysis of colon tumor induction by symmetrical 1,2-dimethylhydrazine (DMH) was undertaken in F1, F2, and reciprocal backcross hybrids derived from a cross between two inbred mouse strains, the 100% susceptible ICR/Ha and completely resistant C57BL/Ha. Mice, 12 to 14 weeks old, received 22 successive weekly s.c. injections of 0.35% aqueous solution of DMH buffered to pH 6.5. A dose of ...

Hybrids between the C4-like species, Flaveria brownii, A. M. Powell and the C3-C4 intermediate species Flaveria linearis Lag., Flaveria floridana Johnston, and Flaveria opposithfoIIa (DC.) Rydb. exhibited bivalent chromosome pairing during meiosis and stainability of pollen was high, ranging from 51 to 95%. An F2 population produced from an F. brownil x F. linearls F1 hybrid, exhibited bivalent...

The combination of cytoplasmic male sterility (CMS) in one parent and a restorer gene (Rf) to restore fertility in another are indispensable for the development of hybrid varieties. To genotype rice lines at the restoring fertility (Rf) loci, 38 lines were crossed with a sterile tester (rfrf) line. Pollen fertility test was performed to identify sterile and fertile F1 hybrids. Seven lines were ...

Drought is a major constraint for sunflower (Helianthus annuus) production worldwide. Drought tolerance traits have been identified in the related wild species Helianthus argophyllus. This study was initiated to develop sunflower drought-tolerant genotypes by crossing cultivated sunflower with this species and analyze drought tolerance traits in the H. annuus and H. argophyllus populations, H. ...

Understanding the likelihood and extent of introgression of novel alleles in hybrid zones requires comparison of lifetime fitness of parents and hybrid progeny. However, fitness differences among cross types can vary depending on biotic conditions, thereby influencing introgression patterns. Based on past work, we predicted that increased competition would enhance introgression between cultivat...

the sugar beet plant has a conical-shaped root and at harvest the tap-root breaks which remains in the soil. as a result, a significant amount of root yield and consequently sugar content is lost. furthermore, the field soil remains in the root fissures and is carried with the root to sugar factory. in rhizomania and nematode-infested areas, the soil movement causes the disease wide spread. in ...

"Ecological" speciation occurs when reproductive isolation evolves as a consequence of divergent selection between populations exploiting different resources or environments. We tested this hypothesis of speciation in a young stickleback species pair by measuring the direct contribution of ecological selection pressures to hybrid fitness. The two species (limnetic and benthic) are strongly diff...

The prevalence of F2 hybrid breakdown in interpopulation crosses of the marine copepod Tigriopus californicus can be explained by disruption of coadapted gene complexes. This study further dissects the nature of hybrid gene interactions, revealing that parental populations may also harbor maladapted gene complexes. Diagnostic molecular markers (14) were assayed in reciprocal F2 hybrids to test ...