Biomechanical comparison of different internal fixation devices for transversely unstable Mason type II radial head fractures

Background: The integrity of the radial head is critical to maintaining elbow joint stability. For radial head fractures requiring surgical treatment, headless compression cannulated screw fixation is a less invasive scheme that has fewer complications. The aim of this study was to compare the mechanical stability of different fixation devices, including headless compression cannulated screws and mini-T-plates, for the fixation of transversely unstable radial head fractures.Methods: Forty identical synthetic radius bones were used to construct transverse unstable radial head fracture models. Parallel, cross, and tripod headless compression cannulated screw fixation and mini-T plate fixation were applied. The structural stiffness of each group was compared by static shear loading. Afterward, cyclic loading was performed in each of the three directions of the radial head, and the shear stability of each group was compared by calculating the maximum radial head displacement at the end of the cycle.Findings: The mini-T plate group had the lowest structural stiffness (51.8 ± 7.7 N/mm) and the highest relative displacement of the radial head after cyclic loading (p < 0.05). The tripod headless compression cannulated screw group had the highest structural stiffness among all screw groups (p < 0.05). However, there was no significant difference in the relative displacement of the radial head between the screw groups after cyclic loading in different directions (p > 0.05).Interpretation: In conclusion, the biomechanical stability of the mini-T plate for fixation of transverse unstable radial head fractures is lower than that of headless compression cannulated screws. Tripod fixation provides more stable fixation than parallel and cross fixation with headless compression cannulated screws for the treatment of transversely unstable radial head fractures

Effects of Tai Chi on telomerase activity and gerotranscendence in middle aged and elderly adults in Chinese society

AbstractIntroductionTelomeres are DNA protein structures at the end of chromosomes and are linked to the physical aging process. The improvement of quality of life is closely associated with aerobic exercise, and the dynamic effects of exercise on physiology and psychology are evident with aging. Tai Chi is popularly practiced in China. However, findings on the effects of Tai Chi on telomerase activity (TA) in peripheral blood mononuclear cells, and gerotranscendence (GT), as well as the association of TA and GT with Tai Chi, have been inconsistent.PurposeThis study aims to assess TA in peripheral blood mononuclear cells, GT, and the associations between them. The associations among these variables are determined during six months of Tai Chi intervention among Chinese middle aged and elderly adults.MethodsTA assessment was obtained by TE-ELISA (human telomerase–enzyme linked immunosorbent assay), and GT was measured at the baseline level after six months of Tai Chi intervention.ResultsTA increased significantly in the Tai Chi group from 23.75 ± 3.78 u/mmol (pre-intervention) to 26.31 ± 2.93 u/mmol (after 6 months) (p < 0.05). Compared with the TA in the control group, the TA in the intervention group was statistically significant after six months (p < 0.05). Compared with the GT in the control group, the GT in the intervention group improved significantly after six months (p < 0.05). TA and GT had a positive correlation (r = 0.325, p < 0.01).ConclusionOur data illustrated that Tai Chi had a protective effect on TA and might improve the GT in Chinese middle aged and elderly adults. The TA increased with the increasing GT in Chinese middle aged and elderly adults

Space-time crystals of trapped ions

Spontaneous symmetry breaking can lead to the formation of time crystals, as well as spatial crystals. Here we propose a space-time crystal of trapped ions and a method to realize it experimentally by confining ions in a ring-shaped trapping potential with a static magnetic field. The ions spontaneously form a spatial ring crystal due to Coulomb repulsion. This ion crystal can rotate persistently at the lowest quantum energy state in magnetic fields with fractional fluxes. The persistent rotation of trapped ions produces the temporal order, leading to the formation of a space-time crystal. We show that these space-time crystals are robust for direct experimental observation. We also study the effects of finite temperatures on the persistent rotation. The proposed space-time crystals of trapped ions provide a new dimension for exploring many-body physics and emerging properties of matter.Comment: updated to the version published in PR

Doped graphenes in catalysis

[EN] Due to the availability and easy preparation, graphenes are currently under intense investigation for various applications in chemistry including their use as metal-free catalysts. The presence in low percentage of heteroatoms on the graphene sheet ("doping") has become a general strategy to modify the electron density, electrical conductivity and other properties of graphenes. The influence of doping can be reflected on the use of these materials in catalysis. After a brief introduction presenting the unique properties and features of graphenes and the reasons why they are suitable to be applicable in catalysis, the present review focuses on those reports describing the use of doped graphenes as metal-free catalyst or as support of metal nanoparticles, electro- and photo-catalysis is excluded. Preparation methods of doped graphenes and adequate characterization techniques providing important information, particularly with respect to the active site in catalysis, are briefly presented before the main body of the review describing common features and relevant examples of the use of doped graphenes in catalysis. Also general traits of graphenes of support of metal nanoparticles have been commented. The final section summarizes the main conclusions and provides our view future developments in the field. The purpose of the present review is not to provide an exhaustive account of all the existing literature, but rather to introduce the reader in the opportunities and advantages that doped graphenes offer with regard to the use either as metal free catalyst or support of metal nanoparticles.Albero, J.; García Gómez, H. (2015). Doped graphenes in catalysis. Journal of Molecular Catalysis A: Chemical. 408:296-309. doi:10.1016/j.molcata.2015.06.011S29630940

Synthetic strategies to nanostructured photocatalysts for CO2 reduction to solar fuels and chemicals

Artificial photosynthesis represents one of the great scientific challenges of the 21st century, offering the possibility of clean energy through water photolysis and renewable chemicals through CO2 utilisation as a sustainable feedstock. Catalysis will undoubtedly play a key role in delivering technologies able to meet these goals, mediating solar energy via excited generate charge carriers to selectively activate molecular bonds under ambient conditions. This review describes recent synthetic approaches adopted to engineer nanostructured photocatalytic materials for efficient light harnessing, charge separation and the photoreduction of CO2 to higher hydrocarbons such as methane, methanol and even olefins

Corrigendum to: The TianQin project: current progress on science and technology

In the originally published version, this manuscript included an error related to indicating the corresponding author within the author list. This has now been corrected online to reflect the fact that author Jun Luo is the corresponding author of the article