The purpose of this investigation was to determine how swimming velocity (SV), stroke rate (SR), stroke length (SL) and blood lactate concentration change as adaptations to six months of aerobic swim training. Subjects were trained male college swimmers (n = 8). Measurements were obtained following specially designed 400m freestyle swim tests, pre- and post-intervention. The swim test consisted of 4 x 400 m freestyle over two days. On day 1, subjects performed a maximal effort 400 m freestyle swimming trial; maximal mean velocity (Vmax) for each swimmer was calculated from this effort. On the next day, subjects were instructed to perform three 400 m freestyle swims at constant velocities equal to 85%, 90% and 95% of Vmax, respectively. Subjects rested one hour between swims. During each 400 m trial, lap time and time to complete 10 mid-pool strokes (50 m) were measured to determine SV (m.s-1), SR (stroke.min-1) and SL (m.stroke-1). Mixed arterial blood samples were taken at the end of each 400 m trial to evaluate blood lactate concentration. Results indicated that post-maximal swimming velocity (Vpostmax) increased significantly from pre-intervention measures (p < 0.05). Blood lactate concentration decreased significantly relative to SV and absolute lactate concentration following Vpostmax was significantly lower than that at Vpremax (p < 0.05). Six of seven subjects increased Vmax due to increases in SL. Mean SL during the second test was significantly higher (p < 0.05). Also, during the 400 m maximal test, SL increased significantly after sixth lap (p < 0.05). There was no significant difference between SRs.(ABSTRACT TRUNCATED AT 250 WORDS)
Energetic ions are emitted from a metal (copper) surface irradiated with femtosecond laser pulses even at extremely low laser fluences. The nonthermal interaction of the pulses with the metal surface is investigated by energy spectroscopy of ions emitted from the surface. Singly charged ions with energies of 180 eV are produced at low fluences of 80 mJ/cm${}^{2}$, and the ion energy spectrum does not follow a shifted Maxwell-Boltzmann distribution. As the mechanism of ion acceleration, Coulomb explosion of nanoparticles on the target surface is proposed. This mechanism is supported by the fairly good agreement between calculated and experimental ion energy spectra and by the relationships of ion energy and ion emission amount with self-organized nanostructures formed on the irradiated surface.
Crystal structures on a single-crystalline copper film with a periodic self-organized surface induced by femtosecond laser pulses with fluences of $0.08--0.64 \mathrm{J}/{\mathrm{cm}}^{2}$ have been analyzed by transmission electron microscopy. It was found that the crystal structures depend on laser fluence: polycrystalline structures are formed at fluences less than $0.2 \mathrm{J}/{\mathrm{cm}}^{2}$, an amorphous state forms around $0.3 \mathrm{J}/{\mathrm{cm}}^{2}$, and polycrystalline structures form again at fluences greater than $0.35 \mathrm{J}/{\mathrm{cm}}^{2}$. The energy spectrum of ions emitted during the formation of periodic structures on the surface shows that the energy of copper ions is high enough to transform the crystal to an amorphous state. A conceptual mechanism for crystal structure transformation by the penetration of energetic ions generated in the process of self-organization of periodic structures is proposed.
Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of solar energy into hydrogen using photosynthetic microorganisms. Our system consists of the following three stages: We constructed a test plant of this process at Nankoh power plant of Kansai Electric Power Company in Osaka, Japan, and carried out a series of tests using CO2obtained from a chemical absorption pilot-plant. The photobiological hydrogen production process used a combination of a marine alga Chlamydomonas sp. MGA 161 and marine photosynthetic bacterium Rhodopseudomonas sp. W-1S. The dark anaerobic fermentation of algal starch biomass was also investigated. Sustained and stable starch accumulation, starch degradation in the algal cell, and hydrogen production from algal fermentation and photosynthetic bacteria in the light were demonstrated during several experiments.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)