Hemodynamic analysis of thoracic endovascular aortic repair with left subclavian artery reconstructed by chimney stent.

OBJECTIVES: The purpose of this study was to investigate the hemodynamic consequences of thoracic endovascular aortic repair which reconstructed left subclavian artery by chimney stent (ch-TEVAR). METHODS: Two patients who underwent thoracic endovascular aortic repair (TEVAR) and left subclavian artery (LSA) reconstruction using chimney stents were selected. Preoperative and postoperative CTA images were collected to reconstruct hemodynamic models for comparing and analyzing blood pressure, blood flow velocity, and wall shear stress in the aortic arch and its major branches. Concurrently, morphological alterations and position of chimney stent were also assessed. RESULTS: After the reconstruction of LSA in ch-TEVAR, no endoleak was seen, but the stent in LSA was compressed. The blood flow velocity of the LSA increased and disordered, the pressure was reduced, and the WSS was increased. Even more, there were a large amount of turbulence found in the LSA of one case, and its LSA was blocked. CONCLUSION: Chimney stent reduces the occurrence of endoleak due to its excellent deformation ability, but the compressed stent has a greater impact on the hemodynamics of LSA and eventually leads to LSA occlusion; in order to keep the LSA unobstructed, it is necessary to pay attention to the position of the chimney stent and keep it straight and do not fold or twist. Chimney stent has little influence on the aortic arch and the rest of the aortic arch branches.

Vertebral artery course variation leading to an insufficient proximal anchoring area for thoracic endovascular aortic repair.

BACKGROUNDS: We aimed to demonstrate the feasibility of thoracic endovascular aortic repair for type B aortic dissection in patients with an insufficient proximal anchoring area due to the vertebral artery originating from the aortic arch. METHODS: In this study, we report two patients with type B aortic dissection who were complicated with left vertebral artery course variation. Specifically, the left vertebral artery originated from the aortic arch. In these patients, the anchoring area (<15 mm) was not sufficient between the left vertebral artery and the ruptured aortic dissection. RESULT: We reconstructed the left vertebral artery during horacic endovascular aortic repair. Both patients recovered well and were discharged without any adverse events. CONCLUTION: Our experience shows that horacic endovascular aortic repair is feasible in patients with type B aortic dissection who have an insufficient proximal anchoring area due to the left vertebral artery originating from the aortic arch.

Progress in the prevention and control of water-borne arsenicosis in China.

In this report, we provided an overview of the prevalence, control, and prevention of water-borne arsenicosis in China during 2001-2016. Random sampling was continuously performed during 2001-2010 to find villages having high levels of arsenic (>50 µg/L) in drinking water. The high-arsenic-exposure villages with more geographically dispersed water supplies were subsequently analyzed for characteristics of arsenic distribution, and villages with relatively large populations were investigated for arsenicosis. The results showed that among 32,673,677 inhabitants in 36,820 villages, 1,894,587 inhabitants in 2,476 villages were at risk of high arsenic exposure. Among the 33,318 drinking water sources surveyed in 625 high-arsenic-exposure villages, 9,807 drinking water sources that contained high levels of arsenic (>50 µg/L) were identified. The overall prevalence rate of arsenicosis was 1.93%. Further, some representative villages were chosen to monitor arsenicosis annually, showing that the prevalence rate of arsenicosis was lower in villages with arsenic-safe water supplies than in villages without arsenic-safe water supplies. To the best of our knowledge, this report provides the most comprehensive assessment of the distribution of high arsenic exposure and arsenicosis in China until now.

In situ-generated NiCo@NiS nanoparticle anchored s-doped carbon nanotubes as dual electrocatalysts for oxygen reduction reaction and hydrogen evolution reaction.

Developing low cost and highly robust electrocatalysts for oxygen evolution reaction, hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) is of great importance for the efficient conversion of sustainable energy sources. Herein, we report a facile pyrolysis strategy for the controllable synthesis of NiCo@NiS/S-CNTs with NiCo@NiS nanoparticles anchored on sulfur-doped carbon nanotubes (CNTs). The obtained NiCo@NiS/S-CNT electrocatalyst exhibits excellent dual-functional catalytic activities under an alkaline condition, an ORR performance with an onset potential of -30 mV, and a half-wave potential of -150 mV (versus Ag/AgCl) while the overpotential for the HER is -1.16 V (versus Ag/AgCl) at a current density of 10 mA cm-2. It was found that the incorporation of sulfur can regulate the electronic structure of CNTs to accelerate the electron transfer performance and generate new catalytic sites, thus contributing to greatly enhancing both the activity and stability of the catalytic process. This work provides a promising way for the rational design of efficient and robust catalysts for sustainable energy conversion.

A systematic review of the agreement between chronological age and skeletal age based on the Greulich and Pyle atlas.

OBJECTIVES: This systematic review examines the agreement between assessed skeletal age by the Greulich and Pyle atlas (GP skeletal age) and chronological age. METHODS: We searched electronic databases until January 2017 for studies reporting GP skeletal age and confirmed chronological age in healthy individuals aged 10-25 years. Results are presented as forest plots and meta-analyses (random-effects models). RESULTS: In separate meta-analyses for each age group and sex (14-18 years for girls, 14-19 years for boys), the pooled mean differences between GP skeletal age and chronological age varied from -0.52 years to 0.47 years. In individual studies, age group and sex-specific mean differences between GP skeletal age and chronological age rarely exceeded 1 year, but between-study heterogeneities were large in most age groups. Few studies examined mean chronological age and distribution for each GP skeletal age. One study of good methodological quality indicates that 95% prediction intervals for chronological age from given GP skeletal ages are typically around 4 years. CONCLUSIONS: There is still good correlation between GP skeletal age and mean chronological age in modern populations. However, the individual variation of development within a population and heterogeneities between studies are substantial. KEY POINTS: • The GP atlas still corresponds well with mean chronological age in modern populations. • The substantial variation within a population must be considered. • The heterogeneity between studies is relatively large and of unknown origin.

Age assessment by Demirjian's development stages of the third molar: a systematic review.

OBJECTIVES: Radiographic evaluation of the wisdom teeth (third molar) formation is a widely used age assessment method for adolescents and young adults. This systematic review examines evidence on the agreement between Demirjian's development stages of the third molar and chronological age. METHODS: We searched four databases up until May 2016 for studies reporting Demirjian's stages of third molar and confirmed chronological age of healthy individuals aged 10-25 years. Heterogeneity test of the included studies was performed. RESULTS: We included 21 studies from all continents except Australia, all published after 2005. The mean chronological age for Demirjian's stages varied considerably between studies. The results from most studies were affected by age mimicry bias. Only a few of the studies based their results on an unbiased age structure, which we argue as important to provide an adequate description of the method's ability to estimate age. CONCLUSION: Observed study variation in the timing of Demirjian's development stages for third molars has often been interpreted as differences between populations and ethnicities. However, we consider age mimicry to be a dominant bias in these studies. Hence, the scientific evidence is insufficient to conclude whether such differences exist. KEY POINTS: • There is significant heterogeneity between studies evaluating age assessment by Demirjian's third molar development. • Most of the studies were subject to the selection bias age mimicry which can be a source of heterogeneity. • Presence of age mimicry bias makes it impossible to compare and combine results. These biased studies should not be applied as reference studies for age assessment.

CerS6 regulates cisplatin resistance in oral squamous cell carcinoma by altering mitochondrial fission and autophagy.

Chemoresistance remains a challenge in the effective treatment of solid tumors, including oral squamous cell carcinoma (OSCC). Mitochondrial dynamics and autophagy have recently been implicated in the chemoresistance of cancer cells. The neutralization of ceramide is also associated with multidrug resistance, and ceramide synthase 6 (CerS6) is known to induce apoptosis. However, whether CerS6 regulates chemoresistance in OSCC is not clearly understood. Therefore, we investigated the role of CerS6 in the susceptibility of OSCC cells to cisplatin. In this study, we observed that cisplatin-resistant OSCC cells process lower levels of fission-state mitochondria and cell apoptosis than cisplatin-sensitive cells, and autophagy was activated in cisplatin-resistant OSCC cells. We found lower CerS6 expression in cisplatin-resistant OSCC cells. Overexpression of CerS6 with lentivirus-encoded CerS6 complementary DNA in cisplatin-resistant OSCC cells increased cisplatin sensitivity. Overexpression of CerS6 enhanced mitochondrial fission and apoptosis and attenuated cisplatin-induced autophagy in cisplatin-resistant OSCC cells. Further investigation indicated that CerS6 might function through altering calpain expression to enhance cisplatin sensitivity. Cisplatin-resistant OSCC cells xenografted onto a nude mouse model confirmed that CerS6 enhanced cisplatin chemotherapy sensitivity to reduce tumor volume. These data indicate that CerS6 could mediate an effective response to cisplatin in chemoresistant OSCC.

Effects of the Informed Health Choices primary school intervention on the ability of children in Uganda to assess the reliability of claims about treatment effects: a cluster-randomised controlled trial.

BACKGROUND: Claims about what improves or harms our health are ubiquitous. People need to be able to assess the reliability of these claims. We aimed to evaluate an intervention designed to teach primary school children to assess claims about the effects of treatments (ie, any action intended to maintain or improve health). METHODS: In this cluster-randomised controlled trial, we included primary schools in the central region of Uganda that taught year-5 children (aged 10-12 years). We excluded international schools, special needs schools for children with auditory and visual impairments, schools that had participated in user-testing and piloting of the resources, infant and nursery schools, adult education schools, and schools that were difficult for us to access in terms of travel time. We randomly allocated a representative sample of eligible schools to either an intervention or control group. Intervention schools received the Informed Health Choices primary school resources (textbooks, exercise books, and a teachers' guide). Teachers attended a 2 day introductory workshop and gave nine 80 min lessons during one school term. The lessons addressed 12 concepts essential to assessing claims about treatment effects and making informed health choices. We did not intervene in the control schools. The primary outcome, measured at the end of the school term, was the mean score on a test with two multiple-choice questions for each of the 12 concepts and the proportion of children with passing scores on the same test. This trial is registered with the Pan African Clinical Trial Registry, number PACTR201606001679337. FINDINGS: Between April 11, 2016, and June 8, 2016, 2960 schools were assessed for eligibility; 2029 were eligible, and a random sample of 170 were invited to recruitment meetings. After recruitment meetings, 120 eligible schools consented and were randomly assigned to either the intervention group (n=60, 76 teachers and 6383 children) or control group (n=60, 67 teachers and 4430 children). The mean score in the multiple-choice test for the intervention schools was 62·4% (SD 18·8) compared with 43·1% (15·2) for the control schools (adjusted mean difference 20·0%, 95% CI 17·3-22·7; p<0·00001). In the intervention schools, 3967 (69%) of 5753 children achieved a predetermined passing score (≥13 of 24 correct answers) compared with 1186 (27%) of 4430 children in the control schools (adjusted difference 50%, 95% CI 44-55). The intervention was effective for children with different levels of reading skills, but was more effective for children with better reading skills. INTERPRETATION: The use of the Informed Health Choices primary school learning resources, after an introductory workshop for the teachers, led to a large improvement in the ability of children to assess claims about the effects of treatments. The results show that it is possible to teach primary school children to think critically in schools with large student to teacher ratios and few resources. Future studies should address how to scale up use of the resources, long-term effects, including effects on actual health choices, transferability to other countries, and how to build on this programme with additional primary and secondary school learning resources. FUNDING: Research Council of Norway.

A comparative evaluation of PDQ-Evidence.

BACKGROUND: A strategy for minimising the time and obstacles to accessing systematic reviews of health system evidence is to collect them in a freely available database and make them easy to find through a simple 'Google-style' search interface. PDQ-Evidence was developed in this way. The objective of this study was to compare PDQ-Evidence to six other databases, namely Cochrane Library, EVIPNet VHL, Google Scholar, Health Systems Evidence, PubMed and Trip. METHODS: We recruited healthcare policy-makers, managers and health researchers in low-, middle- and high-income countries. Participants selected one of six pre-determined questions. They searched for a systematic review that addressed the chosen question and one question of their own in PDQ-Evidence and in two of the other six databases which they would normally have searched. We randomly allocated participants to search PDQ-Evidence first or to search the two other databases first. The primary outcomes were whether a systematic review was found and the time taken to find it. Secondary outcomes were perceived ease of use and perceived time spent searching. We asked open-ended questions about PDQ-Evidence, including likes, dislikes, challenges and suggestions for improvements. RESULTS: A total of 89 people from 21 countries completed the study; 83 were included in the primary analyses and 6 were excluded because of data errors that could not be corrected. Most participants chose PubMed and Cochrane Library as the other two databases. Participants were more likely to find a systematic review using PDQ-Evidence than using Cochrane Library or PubMed for the pre-defined questions. For their own questions, this difference was not found. Overall, it took slightly less time to find a systematic review using PDQ-Evidence. Participants perceived that it took less time, and most participants perceived PDQ-Evidence to be slightly easier to use than the two other databases. However, there were conflicting views about the design of PDQ-Evidence. CONCLUSIONS: PDQ-Evidence is at least as efficient as other databases for finding health system evidence. However, using PDQ-Evidence is not intuitive for some people. TRIAL REGISTRATION: The trial was prospectively registered in the ISRCTN registry 17 April 2015. Registration number: ISRCTN12742235 .

The Contribution of Meckel's Cartilage-Derived Type II Collagen-Positive Cells to the Jawbone Development and Repair.

Jawbones and long bones, despite their shared skeletal lineage, frequently exhibit distinct origins and developmental pathways. Identifying specific progenitor subsets for mandibular osteogenesis remains challenging. Type II collagen is conventionally associated with cartilaginous structures, yet our investigation has identified the presence of type II collagen positive (Col2+) cells within the jawbone development and regeneration. The role of Col2+ cells in jawbone morphogenesis and repair has remained enigmatic. In this study, we analyze single-cell RNA sequencing data from mice jawbone at embryonic day 10.5. Through fate-mapping experiments, we have elucidated that Col2+ cells and their progeny are instrumental in mandibular osteogenesis across both fetal and postnatal stages. Furthermore, lineage tracing with a tamoxifen-inducible CreER system has established the pivotal role of Col2+ cells, marked by Col2-CreER and originating from the primordial Meckel's cartilage, in jawbone formation. Moreover, our research explored models simulating jawbone defects and tooth extraction, which underscored the osteogenic differentiation capabilities of postnatal Col2+ cells during repair. This finding not only highlights the regenerative potential of Col2+ cells but also suggests their versatility in contributing to skeletal healing and regeneration. In conclusion, our findings position Col2+ cells as essential in orchestrating osteogenesis throughout the continuum of mandibular development and repair.

Comparison of Fish, Krill and Flaxseed as Omega-3 Sources to Increase the Omega-3 Index in Dogs.

(1) Background: it is only the longer chain omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (20:5n-3, EPA), and docosahexaenoic acid (22:6n-3, DHA) and not the shorter chain α-linolenic acid (ALA, 18:3n-3) that have been linked to health benefits. (2) Methods: 45 dogs divided into three groups were first given premium dry food for 38 days (baseline). The O3I was then used as a diagnostic tool to provide a measure of the sum of EPA + DHA in red blood cell membranes given as a percentage of all fatty acids. The dogs were subsequently fed with either krill meal (krill), fishmeal/oil (fish) or flaxseed cake (flax) included in raw food providing daily 416 mg EPA + DHA (971 mg ALA), 513 mg EPA + DHA (1027 mg ALA) and 1465 mg ALA (122 mg EPA + DHA), respectively. (3) Results: the average baseline O3I level of all dogs was low (1.36%), warranting n-3 supplementation. After four weeks, O3I levels were significantly increased in the krill (from 1.36 ± 0.44 to 2.36 ± 0.39%) and fish (from 1.35 ± 0.22 to 1.9 ± 0.35%) groups (p < 0.001). No significant modification of the O3I was detected in the flax animals. (4) Conclusions: only marine n-3 PUFAs resulted in a significantly increased O3I, with dietary krill meal providing the highest increase.

Assessment of the Physicochemical Properties of Fragrant Rapeseed Blended Hotpot Oil by Principal Component Analysis.

In this study, a nutritious, healthy Chongqing hotpot oil with excellent flavor was blended while considering nutrition, flavor, and health aspects. Four blended hotpot oils prepared from fragrant rapeseed, palm, sesame, and chicken oils were analyzed to determine their physicochemical properties, antioxidant capacities, levels of harmful substances, and nutritional compositions, and their sensory qualities were evaluated. Principal component analysis was performed to identify the best hotpot oil (10% chicken oil + 20% palm oil + 10% sesame oil + 60% fragrant rapeseed oil), which exhibited good antioxidant capacity (Oxidation Stability Index: 7.95 h; 2,2-diphenyl-1-picrylhydrazyl: 168.6 µmol/kg, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate): 116.7 µmol/kg, and ferric-reducing/antioxidant power: 63.9 µmol/kg), a high sensory score (7.7/10), stable physicochemical properties (acid value: 0.27 mg/g and peroxide value: 0.01 g/100 g), and high tocopherol (54.22%), and phytosterol retention (98.52%) after boiling for 8 h. Although the 3,4-benzopyrene content of this hotpot oil exceeded the EU standard after boiling for 7 h, the increase in the amount of harmful substances was the lowest.

Hierarchically Structured Carbon Nanofiber-Enabled Skin-Like Strain Sensors with Full-Range Human Motion Monitoring and Autonomous Self-Healing Capability.

Flexible strain sensors that mimic the properties of human skin have recently attracted tremendous attention. However, integrating multiple functions of skin into one strain sensor, e.g., stretchability, full-range motion response, and self-healing capability, is still an enormous challenge. Herein, a skin-like strain sensor was presented by the construction of hierarchically structured carbon nanofibers (CNFs), followed by encapsulation of elastic self-healing polyurethane (PU). The hierarchical sensing structure was composed of diversified CNFs with orientations from highly aligned to randomly oriented, and their different fracture mechanisms enabled the resultant strain sensor to successfully integrate key sensing properties including high sensitivity (gauge factor of 90), wide sensing range (∼80% strain), and fast response (52 ms). These properties, combined with high stretchability (870%) and excellent stability (>2000 cycles), allowed the sensor to precisely detect full-range human motions from large joint motions to subtle physiological signals. Moreover, the strain sensor had spontaneous self-healing capability at room temperature with high healing efficiencies of 97.7%, while the healing process could substantially be accelerated by the natural sunlight (24 h → 0.5 h). The healed sensor possessed comparable stretchability, sensing performance, and accurate monitoring ability of subtle body signals with the original sensor. The biomimetic self-healing functionality along with skin-like sensing properties makes it attractive for next-generation wearable electronics.

Primary cilia support cartilage regeneration after injury.

In growing children, growth plate cartilage has limited self-repair ability upon fracture injury always leading to limb growth arrest. Interestingly, one type of fracture injuries within the growth plate achieve amazing self-healing, however, the mechanism is unclear. Using this type of fracture mouse model, we discovered the activation of Hedgehog (Hh) signaling in the injured growth plate, which could activate chondrocytes in growth plate and promote cartilage repair. Primary cilia are the central transduction mediator of Hh signaling. Notably, ciliary Hh-Smo-Gli signaling pathways were enriched in the growth plate during development. Moreover, chondrocytes in resting and proliferating zone were dynamically ciliated during growth plate repair. Furthermore, conditional deletion of the ciliary core gene Ift140 in cartilage disrupted cilia-mediated Hh signaling in growth plate. More importantly, activating ciliary Hh signaling by Smoothened agonist (SAG) significantly accelerated growth plate repair after injury. In sum, primary cilia mediate Hh signaling induced the activation of stem/progenitor chondrocytes and growth plate repair after fracture injury.

Changes in serum thioredoxin among individuals chronically exposed to arsenic in drinking water.

It is well known that oxidative damage plays a key role in the development of chronic arsenicosis. There is a complex set of mechanisms of redox cycling in vivo to protect cells from the damage. In this study, we examined the differences in the levels of serum thioredoxin1 (TRX1) among individuals exposed to different levels of arsenic in drinking water and detected early biomarkers of arsenic poisoning before the appearance of skin lesions. A total of 157 subjects from endemic regions of China were selected and divided into arsenicosis group with skin lesions (total intake of arsenic: 8.68-45.71mg-year) and non-arsenicosis group without skin lesions, which further divided into low (0.00-1.06mg-year), medium (1.37-3.55mg-year), and high (4.26-48.13mg-year) arsenic exposure groups. Concentrations of serum TRX1 were analyzed by an ELISA method. Levels of water arsenic and urinary speciated arsenics, including inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA), were determined by hydride generation atomic absorption spectrometry. Our results showed that the levels of serum TRX1 in arsenicosis patients were significantly higher than that of the subjects who were chronically exposed to arsenic, but without skin lesions. A positive correlation was seen between the levels of serum TRX1 and the total water arsenic intake or the levels of urinary arsenic species. The results of this study indicate that arsenic exposure could significantly change the levels of human serum TRX1, which can be detected before arsenic-specific dermatological symptoms occur. This study provides further evidence on revealing the mechanism of arsenic toxicity.

Characteristics and Antioxidant Activity of Walnut Oil Using Various Pretreatment and Processing Technologies.

This study was the first time the effects of pretreatment technology (microwave roasting, MR; oven roasting, OR; steaming roasting, SR) and processing technology (screw pressing, SP; aqueous enzymatic extraction, AEE; subcritical butane extraction, SBE) on the quality (physicochemical properties, phytochemical content, and antioxidant ability) of walnut oil were systematically compared. The results showed that the roasting pretreatment would reduce the lipid yield of walnut oil and SBE (59.53−61.19%) was the processing method with the highest yield. SR-AEE oil provided higher acid value (2.49 mg/g) and peroxide value (4.16 mmol/kg), while MR-SP oil had the highest content of polyunsaturated fatty acid (73.69%), total tocopherol (419.85 mg/kg) and total phenolic compounds (TPC, 13.12 mg/kg). The DPPH-polar and ABTS free radicals' scavenging abilities were accorded with SBE > AEE > SP. SBE is the recommended process for improving the extraction yield and antioxidant ability of walnut oil. Hierarchical cluster analysis showed that processing technology had a greater impact on walnut oil than pretreatment technology. In addition, multiple linear regression revealed C18:0, δ-tocopherol and TPC had positive effects on the antioxidant ability of walnut oil, while C18:1n-9, C18:3n-3 and γ-tocopherol were negatively correlated with antioxidant activity. Thus, this a promising implication for walnut oil production.

Effect of CNT Content on Microstructure and Properties of CNTs/Refined-AZ61 Magnesium Matrix Composites.

Carbon nanotubes (CNTs) reinforced magnesium matrix composites have great application potential in the transportation industry, but the low absolute strength is the main obstacle to its application. In this paper, copper-coated CNTs and AZ61 powder were used as raw materials to prepare CNTs/refined-AZ61 composites with good interfacial bonding, uniformly dispersed CNTs and fine grains by the process of ball milling refinement of AZ61 powder, ball milling dispersion and hot-pressing sintering. When the volume fraction of CNTs is less than or equal to 1 vol.%, CNTs can be uniformly dispersed and the yield strength and compressive strength of composites increase with higher CNT content. When the volume fraction of CNTs is 1 vol.%, the compressive strength and yield strength of composites reach 439 MPa and 361 MPa, respectively, which are 14% and 9% higher than those of matrix composites with nearly the same value of fracture strain. When the volume fraction of CNTs is greater than 1 vol.%, with the increase in CNT content, CNT clustering becomes more and more serious, resulting in a decrease in the strength and fracture strain of composites.

Strengthening and Toughening CNTs/Mg Composites by OpTimizing the Grinding Time of Magnesium Powder.

In this paper, CNT/Mg composites with high compressive properties were prepared by using Ni-plated CNT and pure magnesium powder as raw materials through the grinding of magnesium powder, ball-milling mixing and hot-pressing sintering. The effect of grinding time for finer magnesium powder on the microstructure and properties of the final composites was studied mainly by SEM, XRD, HRTEM and compression tests. The results show that with the prolongation of milling time, the magnesium particle size decreases gradually and the CNT dispersion becomes more uniform. Moreover, the nickel layer on the surface of CNT reacts with highly active broken magnesium powder in the sintering process to generate MgNi2 intermediate alloy, which significantly improves interface bonding. The strength and fracture strain of composites are significantly increased by the combined action of the uniform distribution of CNTs and strong interface bonding from the MgNi2 phase. The compressive strength, yield strength and fracture strain of the composites, prepared with a 60 h grinding of magnesium powder, reached 268%, 272% and 279% of those in composites without the grinding of magnesium powder.

Influence of Soft Phase and Carbon Nanotube Content on the Properties of Hierarchical AZ61 Matrix Composite with Isolated Soft Phase.

Carbon nanotube-reinforced magnesium matrix (CNTs/Mg) composite has great application potential in the transportation industry, but the trade-off between strength and ductility inhibits its widespread application. In order to balance the strength and plasticity of the composite, in this work, on the basis of the AZ61 matrix composite homogeneously reinforced by Ni-coated CNTs (hard phase), 30 vol.% large-size AZ61 particles are introduced as an isolated soft phase to fabricate hierarchical CNTs/AZ61 composites. The compression tests show the fracture strain and compressive strength of this composite increases by 54% and 8%, respectively, compared with homogeneous CNTs/AZ61 composite. During deformation, the hard phase is mainly responsible for bearing the load and bringing high strength, due to the precipitation of the Mg17Al12 phase, uniformly dispersed CNT and strong interfacial bonding of the CNTs/Mg interface through nickel plating and interfacial chemical reaction. Furthermore, the toughening of the soft phase results in high ductility. With the increase in CNT content, the compressive strength of composites is nearly unchanged but the fracture strain gradually decreases due to the stress concentration of CNT and its agglomeration.

Tracing PRX1+ cells during molar formation and periodontal ligament reconstruction.

Neural crest-derived mesenchymal stem cells (MSCs) are known to play an essential function during tooth and skeletal development. PRX1+ cells constitute an important MSC subtype that is implicated in osteogenesis. However, their potential function in tooth development and regeneration remains elusive. In the present study, we first assessed the cell fate of PRX1+ cells during molar development and periodontal ligament (PDL) formation in mice. Furthermore, single-cell RNA sequencing analysis was performed to study the distribution of PRX1+ cells in PDL cells. The behavior of PRX1+ cells during PDL reconstruction was investigated using an allogeneic transplanted tooth model. Although PRX1+ cells are spatial specific and can differentiate into almost all types of mesenchymal cells in first molars, their distribution in third molars is highly limited. The PDL formation is associated with a high number of PRX1+ cells; during transplanted teeth PDL reconstruction, PRX1+ cells from the recipient alveolar bone participate in angiogenesis as pericytes. Overall, PRX1+ cells are a key subtype of dental MSCs involved in the formation of mouse molar and PDL and participate in angiogenesis as pericytes during PDL reconstruction after tooth transplantation.