Block copolymer self-assembly-directed synthesis of mesoporous gyroidal superconductors

Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly-directed sol-gel-derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (T c) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (J c) of 440 A cm(-2) at 100 Oe and 2.5 K. We expect block copolymer self-assembly-directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies.

Graded porous inorganic materials derived from self-assembled block copolymer templates

Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.

Ordered mesoporous crystalline aluminas from self-assembly of ABC triblock terpolymer–butanol–alumina sols

One-pot synthesis of periodically mesostructured γ-alumina using an ABC triblock terpolymer as structure-directing agent and in situ derived rigid carbon scaffold.

Monolithic gyroidal mesoporous mixed titanium-niobium nitrides

Mesoporous transition metal nitrides are interesting materials for energy conversion and storage applications due to their conductivity and durability. We present ordered mixed titanium-niobium (8:2, 1:1) nitrides with gyroidal network structures synthesized from triblock terpolymer structure-directed mixed oxides. The materials retain both macroscopic integrity and mesoscale ordering despite heat treatment up to 600 °C, without a rigid carbon framework as a support. Furthermore, the gyroidal lattice parameters were varied by changing polymer molar mass. This synthesis strategy may prove useful in generating a variety of monolithic ordered mesoporous mixed oxides and nitrides for electrode and catalyst materials.

Serum enzyme activities in individuals with different levels of physical fitness

Serum creatine phosphokinase (CPK), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activities were assayed in 15 healthy but untrained subjects (US) and seven Olympic rowers (OR). Blood samples were obtained at rest, and five and 60 minutes after an ergometer test, during which cardiorespiratory data were obtained. OR demonstrated higher resting CPK (p < 0.001) and AST (p < 0.05) levels than the US. CPK and AST reached their highest levels five minutes after the end of the ergometer test in both groups, whilst peak ALT was reached five and 60 minutes post-test in the US and OR respectively. Fitness parameters and serum enzyme levels were better correlated in the OR group. It is concluded that: (1) exercise temporarily increases the activities of serum AST, ALT, and CPK, (2) increased physical fitness has no bearing on resting serum ALT enzyme levels, although this was not the case with AST and CPK, and (3) exercise duration rather than fitness levels seems to be related to serum CPK, AST, and ALT activities.