Biomechanical Comparison of Lag Screw and Non-spiral Blade Fixation of a Novel Femoral Trochanteric Nail in an Osteoporotic Bone Model

PurposeThere is no consensus regarding the advantages of the lag screw type over the blade type for treating femoral trochanteric fractures. We aimed to investigate whether non-spiral blade (Conventional-Blade, Fid-Blade) nails provide better biomechanical fixation than lag screws in a severe osteoporotic bone model.MethodsDifferent severities of osteoporotic cancellous bone were modelled using polyurethane foam blocks of three densities (0.24, 0.16, and 0.08 g/cm3). Three torsional tests were performed using each component for each bone density and the maximum torque was recorded, and the energy required to achieve 30° rotation was calculated. Using a push-in test, the maximum force was recorded, and the energy required to achieve 4-mm displacement was calculated. ResultsFor 0.08-g/cm3 density, the peak torques to achieve 30° rotation, energy required to achieve 30° rotation, peak force to achieve 4-mm displacement, and energy required to achieve 4-mm displacement were significantly greater for Conventional-Blade and Fid-Blade than for Lag Screw. ConclusionsConventional-Blade and Fid-Blade nails exhibited significantly higher values than Lag Screw under any test condition. The blade-type nail component may have a better fixation capability than the lag screw type in a severe osteoporotic bone model.

Revealing the High-Modulus Mechanism of Polyimide Films Prepared with 3,4′-ODA

To prepare PIs (polyimides) with desirable thermal and mechanical properties is highly demanded due to their widespread applications in flexible optoelectronic devices and printed circuit boards. Here, the PI films of BPDA/4,4′-ODA, BPDA/3,4′-ODA, PMDA/4,4′-ODA, PMDA/3,4′-ODA systems were prepared, and it was found that the PIs with 3,4′-ODA always exhibit a high modulus compared with the PIs with 4,4′-ODA. To disclose the mechanism of high-modulus PI films with 3,4′-ODA, amorphous PI models and uniaxial drawing PI models were established and calculated based on MD simulation. The PI structural deformations at different length scales, i.e., molecular chain cluster scale and repeat unit scale, under the same stress were detailed and analyzed, including the variation of chain conformation, bond length, bond angle, internal rotation energy, and torsion angle. The results indicate that PIs with 3,4-ODA have higher internal rotation energy and smaller deformation with the same stress, consistent with the high modulus.

Influence of Chain Sharpness, Tension Adjustment and Type of Electric Chainsaw on Energy Consumption and Cross-Cutting Time

Recently, electrical cordless chainsaws were introduced, which provide less harmful working conditions for the operators, and should therefore be deployed as much as possible in all non-professional and professional applications. The low power of the electric engines may result in lower efficiency and higher energy consumption in the case of over-tensioned chains, due to increased friction between the saw and the chain. Therefore, a partial factorial experiment with one factor on three levels (saw type) and two factors on two levels was designed, whereby a wooden beam was cross-cut at two levels of chain sharpness and tension. The time of cross-cutting and energy consumption were controlled. The chain tension does not have a significant effect onto time of cross cutting, or electricity consumption. Both have cross-cutting and energy consumption have been found to differ significantly when comparing the saws used in the experiment. The average efficiency of cross cutting using electrical chainsaws reported is 2.35 times lower than when using petrol powered saws. The lower efficiency is caused by the lower engine power of electrical saws, and lower speed of chain rotation. Energy consumption and time of cross cutting are significantly higher when using a blunt chain, with large differences in time of cross cutting and electricity consumption, making the chain sharpness the most important of all controlled factors. In the study, we did not find evidence that over tensioning of the chain increases the time of cross cutting or energy consumption, however the integration of such systems is recommended because of the worker’s safety.

Applied magnetic cartography is a tool for understanding the self-organization of the planet Earth system and its energy supply

<p>Please insert your abstract HTML here.</p><p>The energy supply of geodynamic processes is one of the most important factors in the evolution of the planet earth system.The continuity and relatively stable regime of the planetary dipole magnetic field of the Earth is due, first of all, to the constant level of rotation energy continuously generated by the Earth during its rotation around its axis. In the mantle, asthenosphere, and the earth's crust, the determining energy factor is the density inhomogeneity of matter.</p><p>The Earth’s magnetic field, which is 99% generated by its internal sources, responds to phase transitions, which are the basis of the processes of self-organization of the planet Earth system.</p><p>The report presents ideas about energy sources, mechanisms and patterns of formation, transformation and replenishment of its reserves will significantly increase the reliability of the interpretation of cartographic information about structural and geophysical anomalies and related mineralogenesis processes.</p>

Environmental Life-Cycle Assessment of Arable Crop Production Technologies Compared to Different Harvesting Work Systems in Short Rotation Energy Plantations

Environmental life cycle assessment (LCA) was developed as a tool for sustainable, decision-supporting environmental management. Applying agricultural sector-LCA in order to achieve both internal (comparative) and external (efficiency enhancing) benefits is a priority. Since the life-cycle assessment of products and processes attracts great interest, applying the method in agriculture is relevant. Our study undertakes a comparative environmental life-cycle assessment (LCA) of local arable crop production technologies used for the main cultivated plants: maize, sunflower, lucerne, cereals, and canola (environmental data in the territorial approach calculated on a 1 ha unit and in the quantitative approach calculated on 1 t of produce). We prepared an environmental inventory of the arable crop production technologies, constructed the life-cycle models, and executed the impact assessment. We also compiled an environmental ranking of technologies. In the impact interpretation, we compared the results with the values of short rotation energy plantations in each impact category. We analysed carbon footprints closely. The obtained results help better assess environmental impacts, climate risks, and climate change as they pertain to arable crop production technologies, which advances the selection of appropriate technologies adjusted to environmental sensitivities.