Search

The homogeneous incorporation of a small concentration of carbon nanotubes (CNTs) in epoxy matrices can enhance the mechanical properties of the composites. However, due to the high van der Waals interaction energy between CNTs, it is difficult to achieve a homogeneous dispersion of them in the epoxy matrix. Both processing conditions of the nanotubes, as well as the addition of surfactants have the potential to improve the dispersion. In this paper, the effects of sonication energy, CNT geometry and dispersant type on the dispersion degree of CNTs and consequent reinforcement of the epoxy matrix are investigated. Multi-walled CNTs with variable diameter and length were dispersed in ethanol using different sonication energies, with the aid of different dispersants. The results show that an increase in sonication energy initially leads to more CNT dispersion, although after a certain value of sonication energy, the level of dispersion remains constant. Moreover, excessive sonication energy was found to shorten the length of CNTs and thus decrease their aspect ratio. Due to the lower interaction energy of CNTs with larger (40–60 nm) diameter, compared to those with smaller diameter (10–20 nm), the larger diameter nanotubes showed a great ability to be dispersed, while CNT length showed no significant effect on the degree of dispersion. For greater CNT dispersion additives were incorporated. Copolymers which were able to disperse the CNTs primarily by steric repulsion were found to be more influential than those which dispersed the CNTs mainly by electrostatic repulsion, such as oleic acid. Furthermore, it was also found that copolymers yielding greater surface charge on the CNT were able to disperse CNTs more than those copolymers leading to a lower surface charge. It was found that, the incorporation of 0.1 wt.% pristine CNT using optimized influential parameters resulted in high levels of homogeneous dispersion in the epoxy matrix, with a modest improvement in mechanical properties of epoxy. This study provides further insight into the dispersion of CNTs in composite matrix and the degree to which a controlled dispersion can allow the CNTs to reach their potential as reinforcing nanofillers. [ABSTRACT FROM AUTHOR]

Structural hierarchy is the key to manufacturing multiscale particle-based composite materials. A novel manufacturing method was developed to generate scalable hierarchical structures in concrete. The new method used 3D-printed microscaffolds to interact with the multiscale particle packing in concrete, resulting in a structured lightweight composite material. The size of internal members can vary by more than two orders of magnitude, to adapt to different applications. Based on compression tests and microstructural investigation by optical microscope and quantitative nanomechanical mapping, we found that the new material is 63.93% more efficient in energy absorption capacity compared with traditional lightweight concrete. Our experimental trials also showed that introducing structural hierarchy can reduce the consumption of cementitious material in the system by up to 14% and significantly reduce the use of scaffolds. The method could be applied to a board spectrum of multiscale particle-based materials, such as dental cement and bone implant materials, to improve material performance and efficiency in medical and construction applications., (Copyright 2023, Mary Ann Liebert, Inc., publishers.)

Injuries and diseases that occur in the nervous system are common and have few effective treatments. Previous studies have shown that quercetin has a therapeutic effect on nervous system injuries, but its potential effects on and mechanisms of action related to behavioral recovery and axonal regrowth have not been investigated. Here, we showed that quercetin administration promotes behavioral recovery following sciatic nerve-crush injury in mice. Long-term evaluation showed that mice administered 20 mg·kg -1 ·day -1 quercetin for 35 days had a greater sensorimotor recovery compared with all other treatment groups. The mechanisms behind these effects were further investigated, and quercetin was found to regulate the expression of genes involved in regeneration and trophic support. Moreover, quercetin increased cyclic adenosine monophosphate expression and downstream pathway activation, which directly leads to neuronal growth activation in peripheral axon regeneration. In addition, quercetin enhanced axon remyelination, motor nerve conduction velocity and plantar muscle function, indicating that the degree of distal portion hypotrophy during the peripheral axon regeneration process was reduced. These results suggest that quercetin accelerates functional recovery by up-regulating neuronal intrinsic growth capacity and postponing distal atrophy. Overall, quercetin triggered multiple effects to promote behavioral recovery following sciatic nerve-crush injury in mice., (Copyright © 2017. Published by Elsevier Inc.)

Ta(NMe(2))(4)[N(SiMe(3))(2)] (1) undergoes the elimination of Me(3)Si-NMe(2) (2), converting the -N(SiMe(3))(2) ligand to the ═NSiMe(3) ligand, to give the imide "Ta(NMe(2))(3)(═NSiMe(3))" (3) observed as its dimer 4. CyN═C═NCy captures 3 to yield guanidinates Ta(NMe(2))(3-n)(═NSiMe(3))[CyNC(NMe(2))NCy](n) [n = 1 (5), 2 (6)]. The kinetic study of α-SiMe(3) abstraction in 1 gives ΔH(‡) = 21.3(1.0) kcal/mol and ΔS(‡) = -17(2) eu.

Aim: To assess the therapeutic value of endoscopic nasobiliary drainage (ENBD) and oral praziquantel for severe Clonorchiasis sinensis infection., Methods: Of the 84 Clonorchiasis sinensis-infected patients enrolled, 58 were treated with ENBD (as observing group, ENBD group), 26 received operations (control group, operation group). Both of the two groups were comparable in terms of patient's age, body mass index. Before and one week after treatment, the average diameters of common bile ducts were measured by ultrasound, and serum bilirubin, ALP, gamma-GT and ALT were detected by biochemical methods. After ENBD or operation, the patients took praziquantel for two days., Results: Compared with the patients in operation group, ENBD patients in ENBD group had higher recovery rates of abdominal pain and fever as well as jaundice, quicker remission, smaller trauma, fewer complications and lower cost., Conclusion: ENBD combined with oral praziquantel is an effective and safe method for the treatment of severe Clonorchiasis sinensis.