Switchable orthorhombic F photonic crystals formed by holographic polymerization-induced phase separation of liquid crystal.

Electrically switchable photonic crystals are simply and rapidly formed by holographic polymerization-induced phase separation of liquid crystal from a monomer-liquid crystal mixture. We report the fabrication and electro-optical properties of liquid-crystal-filled polymer photonic crystals of orthorhombic F symmetry. Inverse opal and fcc structures can also be obtained. The crystals exhibit electrically switchable Bragg diffraction at ~8-10 V/microm with crystal structure in good agreement with theoretical expectations. These photonic crystals compare favorably with liquid-crystal-imbibed colloidal crystal arrays.

The relationship between aerobic fitness and recovery from high intensity intermittent exercise.

A strong relationship between aerobic fitness and the aerobic response to repeated bouts of high intensity exercise has been established, suggesting that aerobic fitness is important in determining the magnitude of the oxidative response. The elevation of exercise oxygen consumption (VO2) is at least partially responsible for the larger fast component of excess post-exercise oxygen consumption (EPOC) seen in endurance-trained athletes following intense intermittent exercise. Replenishment of phosphocreatine (PCr) has been linked to both fast EPOC and power recovery in repeated efforts. Although 31P magnetic resonance spectroscopy studies appear to support a relationship between endurance training and PCr recovery following both submaximal work and repeated bouts of moderate intensity exercise, PCr resynthesis following single bouts of high intensity effort does not always correlate well with maximal oxygen consumption (VO2max). It appears that intense exercise involving larger muscle mass displays a stronger relationship between VO2max and PCr resynthesis than does intense exercise utilising small muscle mass. A strong relationship between power recovery and endurance fitness, as measured by the percentage VO2max corresponding to a blood lactate concentration of 4 mmol/L, has been demonstrated. The results from most studies examining power recovery and VO2max seem to suggest that endurance training and/or a higher VO2max results in superior power recovery across repeated bouts of high intensity intermittent exercise. Some studies have supported an association between aerobic fitness and lactate removal following high intensity exercise, whereas others have failed to confirm an association. Unfortunately, all studies have relied on measurements of blood lactate to reflect muscle lactate clearance, and different mathematical methods have been used for assessing blood lactate clearance, which may compromise conclusions on lactate removal. In summary, the literature suggests that aerobic fitness enhances recovery from high intensity intermittent exercise through increased aerobic response, improved lactate removal and enhanced PCr regeneration.

The relationships between aerobic fitness, power maintenance and oxygen consumption during intense intermittent exercise.

This study examined the relationships between VO2max, power maintenance and oxygen consumption during intense intermittent work. Female recreational soccer players were assigned to either a low aerobic power group (LOW, n = 6, mean (SD) VO2max = 34.4 (2.4) mL.kg(-1)min(-1) or to a moderate aerobic power group (MOD, n = 7, VO2max = 47.6 (3.8) mL.kg(-1).min(-1)). VO2 was measured while subjects performed 10 6-s all-out sprints (30-s passive recovery) on a Monark cycle ergometer. LOW and MOD subjects generated similar peak 6-s power (p = .58) but MOD had a smaller decrement in power (% DO) over the 10 sprints (LOW vs MOD: 18.0 (7.6) vs 8.8 (3.7) % DO, p = .02). The MOD group also consumed significantly more oxygen than LOW in 9 of the 10 sprint-recovery cycles (p < .05). Significant relationships were seen between VO2max and the aerobic response to the sprint-recovery series (r = .78, p =.002) as well as between VO2max and % DO (r = -.65, p = .02), while a non-significant relationship was seen between the oxygen consumed during the sprint-recovery cycles and % DO (r = -.41, p = .16). Thus, VO2max appears to be related to both an increased aerobic contribution to sprint-recovery bouts and the enhanced ability of the MOD group to resist fatigue during intense intermittent exercise.

Ultrafast holographic nanopatterning of biocatalytically formed silica.

Diatoms are of interest to the materials research community because of their ability to create highly complex and intricate silica structures under physiological conditions: what these single-cell organisms accomplish so elegantly in nature requires extreme laboratory conditions to duplicate-this is true for even the simplest of structures. Following the identification of polycationic peptides from the diatom Cylindrotheca fusiformis, simple silica nanospheres can now be synthesized in vitro from silanes at nearly neutral pH and at ambient temperatures and pressures. Here we describe a method for creating a hybrid organic/inorganic ordered nanostructure of silica spheres through the incorporation of a polycationic peptide (derived from the C. fusiformis silaffin-1 protein) into a polymer hologram created by two-photon-induced photopolymerization. When these peptide nanopatterned holographic structures are exposed to a silicic acid, an ordered array of silica nanospheres is deposited onto the clear polymer substrate. These structures exhibit a nearly fifty-fold increase in diffraction efficiency over a comparable polymer hologram without silica. This approach, combining the ease of processability of an organic polymer with the improved mechanical and optical properties of an inorganic material, could be of practical use for the fabrication of photonic devices.