Search results for "Cycling"
showing 10 items of 516 documents
Effects of stump removal on soil decomposer communities in undisturbed patches of the forest floor
2011
Soil preparation after clear-cutting leads to fragmentation of forest floor and, consequently, changes the habitat of decomposers. Stump removal for bioenergy is further increasing the disturbance in the soil. We studied responses of decomposers to stump removal in boreal spruce forests during the first 4 years after clear felling in relation to mounding. Samples for each decomposer organism group were taken from undisturbed forest floor patches that are the main habitat for decomposers after forest regeneration and whose amount and size obviously differ between the treatments. Microbial biomasses and community structure, and the abundance of enchytraeids, were not found to be affected by t…
Importance of static adjustment of knee angle to determine saddle height in cycling
2016
Knee flexion angle is used to determine saddle height during pedaling. However, it is unclear if knee flexion angle at upright standing posture affects measures and interpretation of knee flexion angle during cycling. The objective of this study was to assess the importance of adjusting knee angle during pedaling according to the knee angle at upright posture. Seventeen cyclists performed three 10 min cycling trials at different saddle heights to induce knee flexion angles (40º, 30º or 20º when crank was at the 6 o'clock position). Knee flexion angle was determined at the sagittal plane during cycling using a 2D motion analysis system. Alteration of saddle height was performed by subtractin…
Effect of training on aerobic capacity of female athletes differing in muscle fibre composition
1983
Abstract The effects of endurance training were studied in two groups of female cross‐country skiers who differed in muscle fibre composition. The ST‐group (n = 10) had 56–76% slow twitch (ST) muscle fibres and the FT‐group (n= 10) 40–55% ST fibres in the m. vastus lateralis. During a four‐month period, the subjects trained on the average 81 km per week. The intensive training (heart rate 0–15 beats per min below maximum) averaged 8.5 km per week. The differences in training between the two groups were not significant. The ST‐group significantly increased their cycling maximum oxygen uptake (C max, 4.6%, P <0.01) and the anaerobic threshold (AT, 2.8%, P <0.01) during the training period whe…
Jyväskylän yliopiston ylioppilaskunnan hiili- ja luontojalanjälki
2023
Tässä hankkeessa laskettiin Jyväskylän yliopiston ylioppilaskunnan (JYY) merkittävimpien toimintojen vuoden 2021 hiili- ja luontojalanjälki eli ilmasto- ja luontohaitat. Menetelmä perustuu pääosin muun muassa EXIOBASE ja LC-IMPACT-tietokantoihin, joiden avulla pystytään talouskirjanpitoon perustuen selvittämään eri tuotteiden ja palveluiden aiheuttamat ilmasto- ja luontohaitat sekä niiden maantieteelliset sijainnit. JYY:n vuoden 2021 hiilijalanjälki oli 2017 t CO2e, maaekosysteemeihin kohdistuva luontojalanjälki oli 8,30E-09 PDF (globaali osuus lajeista, jotka ovat riskissä kuolla sukupuuttoon), makean veden ekosysteemeihin kohdistuva luontojalanjälki oli 1,42E-09 PDF ja meriekosysteemeihin…
Multi-layered, covalently supported ionic liquid phase (mlc-SILP) as highly cross-linked support for recyclable palladium catalysts for the suzuki re…
2011
The reaction between an excess of 1,4-bis(3-vinylimidazolium-1-yl) bromide and a mercaptopropyl-modified amorphous silica gel or ordered mesoporous silica SBA-15 in the presence of azobisisobutyronitrile (AIBN) afforded new materials, which have a high loading of imidazolium moieties. These materials, which contain a highly cross-linked polymeric network, have been denoted as multi-layered, covalently supported ionic liquid phase (mlc-SILP) and have been used as support for palladium catalysts containing a high loading of the metal (10 wt%). Such materials were characterized by several techniques (13C magic angle spinning nuclear magnetic resonance, the Brunauer–Emmett–Teller technique, sma…
Recycling of dry and wet polyamide 6
2002
Recycling of polycondensation polymers can give rise to secondary materials with good mechanical properties only if a careful drying is carried out before the melt reprocessing operations. The presence of humidity provokes the hydrolytic chain scission of the macromolecules and the consequent decrease of molecular weight and properties. In this work, the drying step was substituted by the addition of an antioxidant that is able to protect the macromolecules because it is the autioxidant is more prone to hydrolysis, thus removing the water from the melt. The mechanical properties of polyamide 6 reprocessed more times in wet conditions and in the presence of this stabilizer are even better th…
Characterization and Reprocessing of Greenhouse Films.
2001
Films for greenhouses are an attractive source of post-consumer plastic materials because they are mainly made of polyethylene and can be easily collected in large amounts in small zones. The types of polymers for this application are, however, increasing and the films contain not only additives and stabilisers, but also fertiliser and pesticide residues. Finally, the extent of photooxidative degradation undergone during the use can strongly influence the recycling operations and the final properties of the secondary material. In this work, a complete characterisation of post-consumer films for greenhouses has been carried out and the properties of the recycled material have been correlated…
Characterization of monopolymer blend of virgin and recycled polyamide 6
2002
It is a common industrial practice to blend virgin polymer with the same recycled polymer coming from plastic scraps that, in general, has not undergone relevant degradation. In this work, the characteristics of blends of virgin and recycled polyamide have been considered by changing the amount of recycled polymer and the presence of humidity and a stabilizer. Neither dry nor wet stabilized recycled polyamide samples show significant variations of the molecular weight, but the melt Newtonian viscosity of the blends are slightly different from that predicted by an additive rule, despite the same chemical nature of the two components. This holds true even more for the humid unstabilized sampl…
Polymer mechanical recycling: downcycling or upcycling?
2004
Recycled plastics are considered as materials with physical, mechanical and aesthetic properties worse than the virgin ones. In fact, this is true because degradation during lifetime and during the recycling operations changes the structure and the morphology of the polymers and then the final properties of the secondary material. Several “strategies” are under investigation, and in some cases also applied, in order to avoid further degradation during recycling and, if possible, to repair the macromolecules broken during lifetime and then to restore or to improve the initial properties. In this paper the more important techniques, already used in industry or under investigation, according …
Random-strain-field effects on the low-temperature state of KCN
1991
Random strain fields have been introduced into samples of KCN by pressing pellets from powder and by thermal cycling. X-ray diffractograms show that the low-temperature structure depends strongly on the sample history. In some cycles the noncubic low-temperature phases have been suppressed in mesoscopic surface regions of the samples and the quadrupolar-glass state formed instead.