RESUMO
Carbon nanotubes individually show excellent mechanical properties, being one of the strongest known materials. However, when assembled into bundles, their strength reduces dramatically. This still limits the understanding of their scalability. Here, we perform reactive molecular dynamics simulations to study the mechanical resilience and fracture patterns of carbon nanotube bundles (CNTBs) under torsional strain. The results revealed that the fracture patterns of CNTBs are diameter-dependent. The larger the tube diameter, the higher the plasticity degree of the bundle sample when subjected to torsional loading. Tube chirality can also play a role in distinguishing between the CNTBs during the torsion process. Armchair-based CNTBs have higher accumulated energies and, consequently, higher critical angles for the bundle fracture when contrasted with CNTBs composed of zigzag or chiral nanotubes. Remarkably, the CNTB torsional fracture can yield nanodiamondoids.
RESUMO
OBJECTIVE: To identify the effects of robotic gait training practices in individuals with cerebral palsy. DATA SOURCES: The search was performed in the following electronic databases: PubMed, Embase, Medline (OvidSP), Cochrane Database of Systematic Reviews, Web of Science, Scopus, Compendex, IEEE Xplore, ScienceDirect, Academic Search Premier, and Physiotherapy Evidence Database. STUDY SELECTION: Studies were included if they fulfilled the following criteria: (1) they investigated the effects of robotic gait training, (2) they involved patients with cerebral palsy, and (3) they enrolled patients classified between levels I and IV using the Gross Motor Function Classification System. DATA EXTRACTION: The information was extracted from the selected articles using the descriptive-analytical method. The Critical Review Form for Quantitative Studies was used to quantitate the presence of critical components in the articles. To perform the meta-analysis, the effects of the intervention were quantified by effect size (Cohen d). DATA SYNTHESIS: Of the 133 identified studies, 10 met the inclusion criteria. The meta-analysis showed positive effects on gait speed (.21 [-.09, .51]), endurance (.21 [-.06, .49]), and gross motor function in dimension D (.18 [-.10, .45]) and dimension E (0.12 [-.15, .40]). CONCLUSIONS: The results obtained suggest that this training benefits people with cerebral palsy, specifically by increasing walking speed and endurance and improving gross motor function. For future studies, we suggest investigating device configuration parameters and conducting a large number of randomized controlled trials with larger sample sizes and individuals with homogeneous impairment.
