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Anisotropic long-range spin transport in canted antiferromagnetic orthoferrite YFeO3
2022
In antiferromagnets, the efficient transport of spin-waves has until now only been observed in the insulating antiferromagnet hematite, where circularly (or a superposition of pairs of linearly) polarized spin-waves diffuse over long distances. Here, we report long-distance spin-transport in the antiferromagnetic orthoferrite YFeO
3
, where a different transport mechanism is enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields. The magnon decay length is shown to exceed hundreds of nanometers, in line with resonance measurements that highlight the low magnetic damping. We observe a strong anisotropy in the magnon decay lengths that we can attribute to the role of the magnon group velocity in the transport of spin-waves in antiferromagnets. This unique mode of transport identified in YFeO
3
opens up the possibility of a large and technologically relevant class of materials, i.e., canted antiferromagnets, for long-distance spin transport.
Antiferromagnets have attracted interest for spin-based information processing due to their resilience to stray magnetic fields and extremely rapid spin dynamics, however, long range spin wave transport has only been shown in one type of antiferromagnet thus far. Here, Das et al demonstrate long range spin wave transport in antiferromagnetic YFeO3.
Journal Article
Injectable antibacterial conductive nanocomposite cryogels with rapid shape recovery for noncompressible hemorrhage and wound healing
2018
Developing injectable antibacterial and conductive shape memory hemostatic with high blood absorption and fast recovery for irregularly shaped and noncompressible hemorrhage remains a challenge. Here we report injectable antibacterial conductive cryogels based on carbon nanotube (CNT) and glycidyl methacrylate functionalized quaternized chitosan for lethal noncompressible hemorrhage hemostasis and wound healing. These cryogels present robust mechanical strength, rapid blood-triggered shape recovery and absorption speed, and high blood uptake capacity. Moreover, cryogels show better blood-clotting ability, higher blood cell and platelet adhesion and activation than gelatin sponge and gauze. Cryogel with 4 mg/mL CNT (QCSG/CNT4) shows better hemostatic capability than gauze and gelatin hemostatic sponge in mouse-liver injury model and mouse-tail amputation model, and better wound healing performance than Tegaderm™ film. Importantly, QCSG/CNT4 presents excellent hemostatic performance in rabbit liver defect lethal noncompressible hemorrhage model and even better hemostatic ability than Combat Gauze in standardized circular liver bleeding model.
To improve trauma survival and surgical outcomes, hemostatic agents are needed. Here, the authors report on the development of injectable, biocompatible carbon nanotube reinforced quaternized chitosan cryogels with shape memory, conductivity and antibacterial properties for hemostatic control.
Journal Article
Enhanced corrosion resistance by engineering crystallography on metals
2022
Nanometer-thick passive films, which impart superior corrosion resistance to metals, are degraded in long-term service; they are also susceptible to chloride-induced localized attack. Here we show, by engineering crystallographic configurations upon metal matrices adjacent to their passive films, we obtain great enhancement of corrosion resistance of FeCr15Ni15 single crystal in sulphuric acid, with activation time up to two orders of magnitude longer than that of the non-engineered counterparts. Meanwhile, engineering crystallography decreases the passive current density and shifts the pitting potential to noble values. Applying anodic polarizations under a transpassivation potential, we make the metal matrices underneath the transpassive films highly uneven with {111}-terminated configurations, which is responsible for the enhancement of corrosion resistance. The transpassivation strategy also works in the commercial stainless steels where both grain interior and grain boundaries are rebuilt into the low-energy configurations. Our results demonstrate a technological implication in the pretreatment process of anti-corrosion engineering.
Passive films on metal surfaces provide better corrosion resistance, but they can degrade in long-term service. Here the authors demonstrate a strategy to engineer crystallographic configuration at the metal/film interface to further improve corrosion resistance.
Journal Article
Unmasking chloride attack on the passive film of metals
2018
Nanometer-thick passive films on metals usually impart remarkable resistance to general corrosion but are susceptible to localized attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, several classic theories have been proposed and accepted, based on hypotheses and theoretical models, and oftentimes, not sufficiently nor directly corroborated by experimental evidence. Here we show experimental results on the structure of the passive film formed on a FeCr
15
Ni
15
single crystal in chloride-free and chloride-containing media. We use aberration-corrected transmission electron microscopy to directly capture the chloride ion accumulation at the metal/film interface, lattice expansion on the metal side, undulations at the interface, and structural inhomogeneity on the film side, most of which had previously been rejected by existing models. This work unmasks, at the atomic scale, the mechanism of chloride-induced passivity breakdown that is known to occur in various metallic materials.
Collecting experimental evidence of chloride ion attack on protective passive metallic films due to corrosion remains challenging. Here, the authors show that the boundaries between nanocrystals and amorphous regions in the passive film ease chloride transport even as they do not coincide with areas of high chloride concentration.
Journal Article
Synthetic biodegradable functional polymers for tissue engineering: a brief review
2014
Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predomi- nant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly (glyc- erol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, ami- no-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix (ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.
Journal Article
Association between use of benzodiazepines and risk of fractures: a meta-analysis
2014
Summary
Benzodiazepines (BZDs) are some of the most commonly prescribed drugs in the world. It has been shown that BZD use could be associated with increased fracture risk. However, studies on the use of BZDs and fracture risk have yielded inconsistent results. Results from the present meta-analysis show that BZD use is associated with a moderate and clinically significant increase in the risk of fractures.
Introduction
The relationship between the use of BZDs and fracture risk has been neither well identified nor summarized. This meta-analysis reports on the use of BZDs, especially short-acting BZDs, and their correlation with a moderate and clinically significant increase in fracture risk. This analysis will provide evidence for clinicians to consider fracture risk when prescribing BZDs among the elderly population. This study was conducted to determine whether people who take BZDs are at an increased fracture risk.
Methods
A systematic search of studies published through January 2013 was conducted using MEDLINE, EMBASE, OVID, and ScienceDirect. Case–control and cohort studies that assessed the relationship between BZD use and the risk of fractures were identified. Literature searches, study selections, methodological assessments, and data mining were independently conducted by two reviewers. Disagreements were resolved by consensus. STATA 12.0 software was used for the meta-analysis. Random effects models were used for pooled analysis due to heterogeneity among the studies.
Results
There were 25 studies, including 19 case–control studies and 6 cohort studies, that met the inclusion criteria. Overall, the results of the meta-analysis indicated that BZD use was associated with a significantly increased fracture risk (relative risk (RR) = 1.25; 95 % confidence intervals (CI), 1.17–1.34;
p
< 0.001). Increased fracture risk associated with BZD use was observed in participants aged ≥65 years old (RR = 1.26; 95 % CI, 1.15–1.38;
p
< 0.001). When only hip fractures were included as the outcome measure, the RR increased to 1.35. However, subgroup meta-analyses showed that there was no significant association between BZD use and fracture risk in Eastern countries (RR = 1.27; 95 % CI, 0.76–2.14;
p
= 0.362) as well as between long-acting BZD use and risk of fractures (RR = 1.21; 95 % CI, 0.95–1.54;
p
= 0.12). After accounting for publication bias, we observed that the overall association between BZD use and fracture risk to be slightly weaker (RR = 1.21; 95 % CI, 1.13–1.30) but still significant.
Conclusion
The results of this meta-analysis demonstrate that the use of BZD, especially short-acting BZD, is associated with a moderate and clinically significant increase in fracture risk. However, large prospective studies that minimize selection bias are necessary to determine a more accurate fracture risk associated with BZD use.
Journal Article
Quantum interference in heterogeneous superconducting-photonic circuits on a silicon chip
2016
Quantum information processing holds great promise for communicating and computing data efficiently. However, scaling current photonic implementation approaches to larger system size remains an outstanding challenge for realizing disruptive quantum technology. Two main ingredients of quantum information processors are quantum interference and single-photon detectors. Here we develop a hybrid superconducting-photonic circuit system to show how these elements can be combined in a scalable fashion on a silicon chip. We demonstrate the suitability of this approach for integrated quantum optics by interfering and detecting photon pairs directly on the chip with waveguide-coupled single-photon detectors. Using a directional coupler implemented with silicon nitride nanophotonic waveguides, we observe 97% interference visibility when measuring photon statistics with two monolithically integrated superconducting single-photon detectors. The photonic circuit and detector fabrication processes are compatible with standard semiconductor thin-film technology, making it possible to implement more complex and larger scale quantum photonic circuits on silicon chips.
Scaling photonic quantum information processing approaches remains challenging for integrated quantum optics. Here, Schuck
et al.
develop a hybrid superconducting-photonic circuit system to show how quantum interference and single-photon detectors can be combined in a scalable fashion on a silicon chip.
Journal Article
Taming harmful bursts and heat flux in high-confinement tokamak plasmas
2025
A major challenge in tokamak fusion research is first-wall erosion caused by steady heat loads and sudden energy bursts known as edge-localized modes. Divertor detachment reduces steady-state heat flux, while resonant magnetic perturbations can suppress these instabilities. However, integrating the two has been difficult because they require conflicting operating conditions. Here we demonstrate simultaneous achievement of resonant magnetic perturbations mitigated small edge-localized modes and impurity seeded partial divertor detachment in plasmas with an ITER-similar shape on the DIII-D tokamak. Experiments and simulations show that resonant magnetic perturbations facilitate detachment by redistributing particles, lowering the core density and increasing the scrape-off layer density, thereby reducing the amount of injected gas required. Cooling-gas injection eliminates the secondary heat-flux peak created by three-dimensional magnetic lobes, while edge cooling weakens the plasma response to the applied magnetic fields. These advances illustrate a viable pathway for integrating edge stability control with power exhaust in future fusion reactors.
Tokamak walls suffer erosion from steady and bursty heat loads. Here, the authors demonstrate that optimizing 3D magnetic field and cooling gas injection can tame destructive plasma bursts while enabling cooler, safer exhaust conditions.
Journal Article
Nanofibrous hollow microspheres self-assembled from star-shaped polymers as injectable cell carriers for knee repair
2011
To repair complexly shaped tissue defects, an injectable cell carrier is desirable to achieve an accurate fit and to minimize surgical intervention. However, the injectable carriers available at present have limitations, and are not used clinically for cartilage regeneration. Here, we report nanofibrous hollow microspheres self-assembled from star-shaped biodegradable polymers as an injectable cell carrier. The nanofibrous hollow microspheres, integrating the extracellular-matrix-mimicking architecture with a highly porous injectable form, were shown to efficiently accommodate cells and enhance cartilage regeneration, compared with control microspheres. The nanofibrous hollow microspheres also supported a significantly larger amount of, and higher-quality, cartilage regeneration than the chondrocytes-alone group in an ectopic implantation model. In a critical-size rabbit osteochondral defect-repair model, the nanofibrous hollow microspheres/chondrocytes group achieved substantially better cartilage repair than the chondrocytes-alone group that simulates the clinically available autologous chondrocyte implantation procedure. These results indicate that the nanofibrous hollow microspheres are an excellent injectable cell carrier for cartilage regeneration.
Nanofibrous hollow microspheres, formed by the self-assembly of star-shaped biodegradable polymers, are shown to be effective injectable cell carriers for cartilage repair. The microspheres accommodate cells and enhance cartilage regeneration
in vivo
with respect to various control groups, in particular, indicating smooth integration between the regenerated and host tissue.
Journal Article