ABSTRACT
Non-trivial topological structures, such as vortex-antivortex (V-AV) pairs, have garnered significant attention in the field of condensed matter physics. However, the detailed topological phase transition dynamics of V-AV pairs, encompassing behaviors like self-annihilation, motion, and dissociation, have remained elusive in real space. Here, polar V-AV pairs are employed as a model system, and their transition pathways are tracked with atomic-scale resolution, facilitated by in situ (scanning) transmission electron microscopy and phase field simulations. This investigation reveals that polar vortices and antivortices can stably coexist as bound pairs at room temperature, and their polarization decreases with heating. No dissociation behavior is observed between the V-AV phase at room temperature and the paraelectric phase at high temperature. However, the application of electric fields can promote the approach of vortex and antivortex cores, ultimately leading to their annihilation near the interface. Revealing the transition process mediated by polar V-AV pairs at the atomic scale, particularly the role of polar antivortex, provides new insights into understanding the topological phases of matter and their topological phase transitions. Moreover, the detailed exploration of the dynamics of polar V-AV pairs under thermal and electrical fields lays a solid foundation for their potential applications in electronic devices.
ABSTRACT
OBJECTIVE: This systematic review aimed to analyse the effect of early weight bearing versus late weight bearing on rehabilitation outcomes after ankle fractures, which primarily include ankle function scores, time to return to work/daily life and complication rates. METHODS: The China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform, China Science and Technology Journal, Web of Science, PubMed, Embase and Cochrane Library databases were searched. The focus was on identifying randomised controlled trials centred on early weight-bearing interventions for post-operative ankle fracture rehabilitation. All databases were searched for eligible studies published within the period from database inception to 20 June 2023. The eligible studies were screened according to the inclusion criteria. Study quality was evaluated using the methodology recommended by the Cochrane Handbook for the Systematic Evaluation of Interventions. Two authors independently performed the literature search and data extraction. Eligible studies were subjected to meta-analyses using Review Manager 5.3. Based on the time points at which post-operative ankle function was reported in the studies included in this paper, we decided to perform a meta-analysis of ankle function scores at 6 weeks post-operatively, 12 weeks post-operatively, 24-26 weeks post-operatively and 1 year post-operatively. RESULTS: A total of 11 papers, comprising 862 patients, were included. Meta-analysis indicated that patients receiving early weight-bearing interventions, which referred to weight-bearing for 6 weeks post-operatively, experienced enhancements in ankle function scores (Olerud-Molander score, AOFAS score or Baird-Jackson score) at various post-operative milestones: 6 weeks (SMD = 0.69, 95% CI: 0.49-0.88 and p < 0.01), 12 weeks (SMD = 0.57, 95% CI: 0.22-0.92 and p < 0.01) and the 24-26 weeks range (SMD = 0.52, 95% CI: 0.20-0.85 and p < 0.01). The results of subgroup analyses revealed that the effects of early weight-bearing interventions were influenced by ankle range-of-motion exercises. Additionally, early weight bearing allows patients to return to daily life and work earlier, which was evaluated by time when they resumed their preinjury activities (MD = -2.74, 95% CI: -3.46 to -2.02 and p < 0.01), with no distinct elevation in the incidence of complications (RR = 1.49, 95% CI: 0.85-2.61 and p > 0.05). CONCLUSION: The results showed that early weight bearing is effective in improving ankle function among post-operative ankle fracture patients and allows patients to return to daily life earlier. Significantly, the safety profile of early weight bearing remains favourable, with no higher risk of complications than late weight bearing.
Subject(s)
Ankle Fractures , Humans , Ankle Fractures/surgery , Treatment Outcome , China , Weight-Bearing , Randomized Controlled Trials as TopicABSTRACT
The laser cleaning effect can be affected by many parameters, including laser power, scanning speed, laser repetition rate, and pulse duration, and the cleaning effect with these parameters is investigated. It is found that the cleaning effect is negligible for an infrared high-repetition nanosecond-pulsed laser with repetition rate from 100 to 400 kHz and pulse duration from 58 to 240 ns and is significantly related to the laser power and scanning speed. Moreover, the cleaning thresholds related to laser power and scanning speed for a soil rust layer on ceramic artifacts are measured under the step distance of 281.3 µm. The heat conduction equation and thermal stress equation are used to simulate the cleaning effect with the influence of these parameters, which is in good agreement with the experimental data.
ABSTRACT
A novel bidirectional ring amplifier with twin pulses for high-power lasers is proposed, and the performances on output energy capability and extraction efficiency are comprehended with detailed simulation. The results show that an extraction efficiency of 62.3% and the output energy of 13.4 kJ per pulse at the B integral limit can be obtained at low average fluence of 10.3 J/cm2 and the low injection energy of 3.9 mJ in the bidirectional ring amplifier. Compared with the multi-pass amplifier, the bidirectional ring amplifier is more compact and the extraction efficiency is much higher at low injection energy and low laser fluence operation, which is beneficial to simplify the preamplifier system and reduce the effects of nonlinear phase shift.
ABSTRACT
The cathode interlayer is of crucial importance for efficient electron injection in inverted polymer light-emitting diodes (PLEDs) to realize high electroluminescence efficiency. Here, a novel photoconductive cathode interlayer based on organic dye-doped ZnO (ZnO:PBI-H) is applied as the cathode buffer layer in PLEDs, and dramatically enhanced device performance is obtained. The photodoping of ZnO may greatly promote the electron injection ability under the device working conditions, which increases the electron-hole recombination efficiency when using P-PPV as the light-emitting material. Thanks to the decreased energy barrier between the cathode interlayer and the light-emitting layer, the turn-on voltage of the PLEDs is obviously reduced when using the photoconductive cathode interlayer. Our results indicate that photodoping of the cathode interlayer is a promising strategy to increase the interlayer performance in light-emitting diodes.
ABSTRACT
Aiming for a three-lens slit spatial filtering system with excellent performances in inhibition of pinhole closure, improvement of beam quality, compactness of the system, and lowering the requirement of vacuum, the filtering characteristics and image relay of the slit spatial filter are demonstrated. The results show that the beam quality is greatly improved, and the system has a good property in image relay, which has potential applications in high-power lasers.
ABSTRACT
Inverted-type polymer light-emitting diodes with Au nanoparticles modified ITO cathode has exhibited improved brightness from 5900 to 15,000 cd m(-2) (1.5-fold enhancement) and enhanced luminous efficiency from 4.4 to 10.5 cd A(-1) (1.4-fold enhancement), when greenish emissive polymer-P-PPV was applied as active layer. Both the experimental and theoretical results show that it is mainly attributed to effective overlapping between local surface plasmon resonance induced by Au nanopartices and excitons quenching region at ZnO/P-PPV interface, which makes originally electrode-quenched excitons emissive and increases excitons efficiency.
