Computational evaluation of wire position using separate vertical wire technique and candy box technique for the fixation of inferior pole patellar fractures: a finite element analysis

The separate vertical wire (SVW) technique and the improved candy box (CB) technique have been proposed for treating inferior pole patellar fractures. However, there is still a lack of clear explanation regarding the location of the wire passing through the patella. Five models of SVW techniques were established in different positions. Finite element analysis was then conducted to determine the optimal bone tunnel position for the SVW technique. Based on these findings, six groups of finite element models were created for CB techniques. The maximum displacement and stress on both the patella and steel wire were compared among these groups under 100-N, 200-N, 300-N, 400-N, and 500-N force loads. The results indicated that, in the SVW technique, the steel wire group near the fracture end of the longitudinal bone tunnel showed minimal displacement and stress on the patella when subjected to different forces. On the other hand, in the CB technique, both the patella and wire experienced minimal stress when a transverse bone tunnel wire was placed near the upper posterior aspect of patella. In conclusion, the SVW technique may require the bone tunnel wire to be positioned near the fractured end of the lower pole of the patella. On the other hand, in CB technique, the transverse bone tunnel wire passing through the patella may be close to its upper posterior aspect. However, further validation is necessary through comprehensive finite element analysis and additional biomechanical experiments

Environmentally benign metal catalyst for the ring-opening copolymerization of epoxide and CO2: state-of-the-art, opportunities, and challenges

Carbon dioxide (CO2) is the main greenhouse gas, whereas it is also a nontoxic, abundant, cheap carbon and oxygen resource. The copolymerization of CO2 with epoxide presents a sustainable approach to the synthesis of biodegradable polymers, which upcycles the waste into wealth. Metal complex catalyst plays the central role in the reaction, since it provides oxophilic and Lewis acidic active center both for monomer activation and chain end stabilization, and nucleophiles as Lewis base for initiation. However, heavy metal catalyst with certain toxicity such as cobalt undisputedly dominates the copolymerization catalysis which comprises the overall sustainability. To circumvent the potential environmental hazard, developing highly active catalyst composed of green metals is of great importance especially when the polymer was utilized for agriculture purpose. This work reviews the development of sustainable metal catalysts for the production of CO2 copolymer, centered by Al, Mg, Ti, Fe, generally acknowledged as low toxic, environmentally benign, biocompatible, and also abundant in earth's crust. Emphasis is placed in recent five years where several historic examples are also included to construct a full picture of the sustainable catalysis explored to date

Polymerization-Enhanced Photophysical Performances of AIEgens for Chemo/Bio-Sensing and Therapy

AIE polymers have been extensively researched in the fields of OLEDs, sensing, and cancer treatment since its first report in 2003, which have achieved numerous breakthroughs during the years. In comparison with small molecules, it can simultaneously combine the unique advantages of AIE materials and the polymer itself, to further enhance their corresponding photophysical performances. In this review, we enumerate and discuss the common construction strategies of AIE-active polymers and summarize the progress of research on polymerization enhancing luminescence, photosensitization, and room-temperature phosphorescence (RTP) with their related applications in chemo/bio-sensing and therapy. To conclude, we also discuss current challenges and prospects of the field for future development

Acoustic Stimulation Improves Memory and Reverses the Contribution of Chronic Sleep Deprivation to Pathology in 3xTgAD Mice

Objective: Acoustic stimulation during sleep is believed to enhance slow waves, which are critical to memory consolidation. However, clinical trials of acoustic stimulation have yielded mixed results concerning its effectiveness in improving human memory. A few studies have implied that acoustic stimulation ameliorates the pathology of Alzheimer’s disease (AD) in mice with normal sleep. Here, we explored the effect of acoustic stimulation on 3xTgAD mice suffering from chronic sleep deprivation, as these data may shed light on the potential use of acoustic stimulation in AD patients with insomnia. Methods: Twenty-four 8-month-old 3xTgAD mice were randomly and equally divided into three groups: the normal sleep group (S group), the sleep deprivation group (SD group), and the acoustic stimulation group (AS group). During a 14-day sleep intervention, the SD and AS groups received 6 h of sleep deprivation per day, and the AS group also received acoustic stimulation in the dark phase. Then, the mice underwent Morris water maze (MWM) tests and arterial spin labelling (ASL) magnetic resonance imaging (MRI) scans and were sacrificed for pathological evaluation. Results: The three groups showed similar stress levels. The S and AS groups exhibited better spatial memory, better brain perfusion, and milder amyloid β (Aβ) and tau pathology than the SD group, although no significant discrepancies were found between the S and AS groups. Conclusions: Acoustic stimulation may exert a protective effect in 3xTgAD mice by improving spatial memory, enhancing the blood supply of the brain, and reversing the contribution of chronic sleep deprivation to Aβ and tau pathology to mimic the effect of normal sleep patterns

Multi-source localization on complex networks based on community detection

Source localization is a crucial task on complex networks to understand the transmission mechanism and eliminate the malignant influence of diffusion processes. The previous works mainly detect multiple sources from a global perspective within a network. In this paper, we introduce community detection to source localization, aiming to address source localization from a local view. Specifically, a community detection-based multi-source localization method CDSL is proposed. Experiments on both several real-world and synthetic networks demonstrate that CDSL has higher accuracy and needs less runtime than the existing source localization methods. We also explore how different observation selection strategies affect the performance of CDSL and find out that selecting the nodes with a small degree as observers performs best

Polymerization-Induced Emission

This article highlights the recent developments of unorthodox luminescent polymers without large p-conjugated structure and their luminescence mechanism in last 2–3 years. Non-conjugated luminescent polymers (NCLPs) will be a wonderful polymer that will provide new soft luminescent materials. Uniting polymer synthesis and photophysical science, Polymerization-Induced Emission (PIE) is proposed for making NCLPs because the advanced polymerization methods have unlimited opportunities to the development of new soft luminescent polymers owing to the multi-level structures of polymers. The importance of this paper is to inspire more thoughts on the emission mechanism of the non-conjugated polymers and developing new soft luminescent materials.</p

Acoustic stimulation during sleep improves cognition and ameliorates Alzheimer's disease pathology in APP/PS1 mice

Nonpharmacological therapies for Alzheimer's disease (AD) have become a popular research topic, and acoustic stimulation during sleep is one such promising strategy for the clinical treatment of AD. Some animal experiments have illustrated that acoustic stimulation at a specific frequency can ameliorate AD-related pathology or improve cognition in mice, but these studies did not explore the effective time window of auditory stimulation. Here, we explored the effects of acoustic stimulation during wakefulness and acoustic stimulation during sleep on cognition and AD-related pathology in APP/PS1 mice and the underlying mechanisms. In this study, forty APP/PS1 mice were equally divided into the following 4 groups and treated for 28 days: the chronic sleep deprivation (CSD) group (exposed to sleep deprivation from zeitgeber time [ZT] 0 to ZT 12 each day), the normal sleep and stress exposure (NSS) group (exposed to a stressor from ZT 0 to ZT 12 each day), the acoustic stimulation during wakefulness (ASW) group (exposed to sleep deprivation and 40 Hz acoustic stimulation from ZT 0 to ZT 12 each day) and the acoustic stimulation during sleep (ASS) group (exposed to sleep deprivation from ZT 0 to ZT 12 and 40 Hz acoustic stimulation from ZT 12 to ZT 24 each day). After the intervention, cognition was assessed by behavioural experiments. The amyloid-β burden was analysed by Western blotting, immunofluorescence and enzyme-linked immunosorbent assay. Tau pathology was assessed by Western blotting. Mitochondrial function was evaluated by transmission electron microscopy, Western blotting and fluorescence intensity measurement. We found that the NSS and ASS groups had better cognitive functions than the CSD and ASW groups. The Aβ burden and tau phosphorylation were lower in the NSS and ASS groups than in the CSD and ASW groups. Mitochondrial function was better in the NSS and ASS groups than in the CSD and ASW groups. However, the differences in these parameters between the NSS and ASS groups and between the CSD and ASW groups were not significant. Our findings suggest that acoustic stimulation at a specific frequency during sleep, but not during wakefulness, reduces the amyloid-β burden by inhibiting amyloid beta precursor protein-binding protein 2, hinders tau phosphorylation by blocking glycogen synthase kinase 3 beta, and restores mitochondrial function by elevating mitophagy and promoting mitochondrial biogenesis

Progressive Failure and Fracture Mechanism of Sandstone under Hydraulic-Mechanical Coupling

Hydraulic coupling often leads to progressive rock failure accidents. Mechanical tests were performed over a range of combined pore water pressure and confining pressure stress path conditions to study the progressive failure characteristics of sandstone under hydraulic-mechanical coupling and explore the crack initiation and pore water fracture mechanism. The closure stress and damage stress were determined by the axial deformation stiffness and volume deformation stiffness. The experimental results indicate that confining pressure is the main controlling factor in the crack propagation stage, and pore water pressure enhances crack evolution. With increasing effective confining pressure, the effective peak deviatoric stress strongly increases and the characteristic stress increases linearly. The initiation stress and damage stress decrease with increasing pore water pressure. The moduli in stages I, II, and III are similar to the law of the transverse and radial deformation ratio with notable differences in stage IV. The fracture trend angle was determined by the ratio of axial crack strain and radial crack strain. Compared with the experimental results, the internal cracks in the sandstone samples are mainly type-II cracks, and type-I cracks are also locally present. After stress damage, the cracks expand and extend at an angle close to the real fracture

Effects of Unloading Rate on Energy Evolution Mechanism in the Single-Side Unloading Failure of Highly Stressed Marble

Highly stressed rock masses continuously exchange substances and energy with the outer environment during single-side unloading, which is a damage evolution process with energy dissipation. The true triaxial unloading disturbance rock test system was utilized to perform single-side unloading tests of marble specimens at different unloading rates and axial pressures. The unloading failure characteristics of the marble specimens were revealed from the perspective of energy conversion. Results indicated the following: (1) The marble specimen was more likely to be damaged under the single-side unloading condition than under the loading condition, with the unloading failure strength reaching 80% of the loading failure strength. (2) Crack propagation under single-side unloading was intermittent. (3) A high single-side unloading rate corresponded to a high release rate of the energy concentrated inside the rock mass, a small amount of energy dissipated due to second failure, insufficient crack propagation, and occurrence of only tensile failure. (4) A large amount of axial strain energy indicated a great amount of energy aggregated inside the rock mass and the generation of tensile stress due to unloading dilatancy. Consequently, a high critical value for splitting the failure of the rock specimen implied large failure-induced energy dissipation and a high failure degree. The study of failure energy evolution mechanism in the single-side unloading of highly stressed rock masses at different unloading rates will provide great guiding significance in controlling underground engineering disasters and guaranteeing construction safety

Effects of Unloading Rate on Energy Evolution Mechanism in the Single-Side Unloading Failure of Highly Stressed Marble

Highly stressed rock masses continuously exchange substances and energy with the outer environment during single-side unloading, which is a damage evolution process with energy dissipation. The true triaxial unloading disturbance rock test system was utilized to perform single-side unloading tests of marble specimens at different unloading rates and axial pressures. The unloading failure characteristics of the marble specimens were revealed from the perspective of energy conversion. Results indicated the following: (1) The marble specimen was more likely to be damaged under the single-side unloading condition than under the loading condition, with the unloading failure strength reaching 80% of the loading failure strength. (2) Crack propagation under single-side unloading was intermittent. (3) A high single-side unloading rate corresponded to a high release rate of the energy concentrated inside the rock mass, a small amount of energy dissipated due to second failure, insufficient crack propagation, and occurrence of only tensile failure. (4) A large amount of axial strain energy indicated a great amount of energy aggregated inside the rock mass and the generation of tensile stress due to unloading dilatancy. Consequently, a high critical value for splitting the failure of the rock specimen implied large failure-induced energy dissipation and a high failure degree. The study of failure energy evolution mechanism in the single-side unloading of highly stressed rock masses at different unloading rates will provide great guiding significance in controlling underground engineering disasters and guaranteeing construction safety