ABSTRACT
Effective control and readout of qubits form the technical foundation of next-generation, transformative quantum information sciences and technologies. The nitrogen-vacancy (NV) center, an intrinsic three-level spin system, is naturally relevant in this context due to its excellent quantum coherence, high fidelity of operations, and remarkable functionality over a broad range of experimental conditions. It is an active contender for the development and implementation of cutting-edge quantum technologies. Here, we report magnetic domain wall motion driven local control and measurements of the NV spin properties. By engineering the local magnetic field environment of an NV center via nanoscale reconfigurable domain wall motion, we show that NV photoluminescence, spin level energies, and coherence time can be reliably controlled and correlated to the magneto-transport response of a magnetic device. Our results highlight the electrically tunable dipole interaction between NV centers and nanoscale magnetic structures, providing an attractive platform to realize interactive information transfer between spin qubits and nonvolatile magnetic memory in hybrid quantum spintronic systems.
ABSTRACT
van der Waals (vdW) magnets, an emerging family of two-dimensional (2D) materials, have received tremendous attention due to their rich fundamental physics and significant potential for cutting-edge technological applications. In contrast to the conventional bulk counterparts, vdW magnets exhibit significant tunability of local material properties, such as stacking engineered interlayer coupling and layer-number dependent magnetic and electronic interactions, which promise to deliver previously unavailable merits to develop multifunctional microelectronic devices. As a further ingredient of this emerging topic, here we report nanoscale quantum sensing and imaging of the atomically thin vdW magnet chromium thiophosphate CrPS4, revealing its characteristic layer-dependent 2D static magnetism and dynamic spin fluctuations. We also show a large tunneling magnetoresistance in CrPS4-based spin filter vdW heterostructures. The excellent material stability and robust strategy against environmental degradation in combination with tailored magnetic properties highlight the potential of CrPS4 in developing state-of-the-art 2D spintronic devices for next-generation information technologies.
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Noncollinear antiferromagnets with novel magnetic orders, vanishingly small net magnetization, and exotic spin related properties hold enormous promise for developing next-generation, transformative spintronic applications. A major ongoing research focus of this community is to explore, control, and harness unconventional magnetic phases of this emergent material system to deliver state-of-the-art functionalities for modern microelectronics. Here we report direct imaging of magnetic domains of polycrystalline Mn3Sn films, a prototypical noncollinear antiferromagnet, using nitrogen-vacancy-based single-spin scanning microscopy. Nanoscale evolution of local stray field patterns of Mn3Sn samples are systematically investigated in response to external driving forces, revealing the characteristic "heterogeneous" magnetic switching behaviors in polycrystalline textured Mn3Sn films. Our results contribute to a comprehensive understanding of inhomogeneous magnetic orders of noncollinear antiferromagnets, highlighting the potential of nitrogen-vacancy centers to study microscopic spin properties of a broad range of emergent condensed matter systems.
ABSTRACT
Emergent color centers with accessible spins hosted by van der Waals materials have attracted substantial interest in recent years due to their significant potential for implementing transformative quantum sensing technologies. Hexagonal boron nitride (hBN) is naturally relevant in this context due to its remarkable ease of integration into devices consisting of low-dimensional materials. Taking advantage of boron vacancy spin defects in hBN, we report nanoscale quantum imaging of low-dimensional ferromagnetism sustained in Fe3GeTe2/hBN van der Waals heterostructures. Exploiting spin relaxometry methods, we have further observed spatially varying magnetic fluctuations in the exfoliated Fe3GeTe2 flake, whose magnitude reaches a peak value around the Curie temperature. Our results demonstrate the capability of spin defects in hBN of investigating local magnetic properties of layered materials in an accessible and precise way, which can be extended readily to a broad range of miniaturized van der Waals heterostructure systems.
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Novel non-collinear antiferromagnets with spontaneous time-reversal symmetry breaking, non-trivial band topology, and unconventional transport properties have received immense research interest over the past decade due to their rich physics and enormous promise in technological applications. One of the central focuses in this emerging field is exploring the relationship between the microscopic magnetic structure and exotic material properties. Here, nanoscale imaging of both spin-orbit-torque-induced deterministic magnetic switching and chiral spin rotation in non-collinear antiferromagnet Mn3 Sn films using nitrogen-vacancy (NV) centers are reported. Direct evidence of the off-resonance dipole-dipole coupling between the spin dynamics in Mn3 Sn and proximate NV centers is also demonstrated by NV relaxometry measurements. These results demonstrate the unique capabilities of NV centers in accessing the local information of the magnetic order and dynamics in these emergent quantum materials and suggest new opportunities for investigating the interplay between topology and magnetism in a broad range of topological magnets.
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BACKGROUND: One of the greatest challenges for tissue-engineered bone is the low survival rate of locally grafted cells. The cell homing technology can effectively increase the number of these grafted cells, therefore, enhancing the repair of bone defects. Here we explore the effect of fucosylation modification on the directional homing of bone marrow mesenchymal stem cells (BMSCs) and their ability to repair bone defects. RESULTS: Glycosylated BMSCs expressed high levels of the Sialyl Lewis-X (sLeX) antigen, which enabled the cells to efficiently bind to E- and P-selectins and to home to bone defect sites in vivo. Micro-CT and histological staining results confirmed that mice injected with FuT7-BMSCs showed an improved repair of bone defects compared to unmodified BMSCs. CONCLUSIONS: The glycosylation modification of BMSCs has significantly enhanced their directional homing ability to bone defect sites, therefore, promoting bone repair. Our results suggest that glycosylation-modified BMSCs can be used as the source of the cells for the tissue-engineered bone and provide a new approach for the treatment of bone defects.
Subject(s)
Bone Marrow , Bone Regeneration , Mesenchymal Stem Cells/metabolism , Tissue Engineering , Animals , Glycosylation , Male , Mesenchymal Stem Cell Transplantation/methods , Mesenchymal Stem Cells/pathology , Mice , Osteogenesis , Tissue Scaffolds , X-Ray MicrotomographyABSTRACT
Excitons have fundamental impacts on optoelectronic properties of semiconductors. Halide perovskites, with long carrier lifetimes and ionic crystal structures, may support highly mobile excitons because the dipolar nature of excitons suppresses phonon scattering. Inspired by recent experimental progress, we perform device modeling to rigorously analyze exciton formation and transport in methylammonium lead triiodide under local photoexcitation by using a finite element method. Mobile excitons, coexisting with free carriers, can dominate photocurrent generation at low temperatures. The simulation results are in excellent agreement with the experimentally observed strong temperature and gate dependence of carrier diffusion. This work signifies that efficient exciton transport can substantially influence charge transport in the family of perovskite materials.
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BACKGROUND: The purpose of this study is to investigate the optimal surgical options for different kinds of advanced hip tuberculosis, which are still controversial. METHODS: We reviewed seven advanced hip tuberculosis patients received operations from November 2014 to September 2018. All patients received anti-tubercular chemotherapy at least 2 weeks preoperatively and twelve months postoperatively. One active case with sinus tract of seven patients underwent three-stage operations including two debridements/cement spacer implantations and one total hip arthroplasty, while the other six cases received one = stage arthroplasty surgery. All patients are followed up based on Harris score, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and X-ray. RESULTS: The mean follow-up time was 41.6 months, while no reactivation was detected. The average Harris score increased from 40.0 preoperatively to 89.4 at the final follow-up. ESR of 3 active hip tubercular cases decreased from 143.7 mm/L at diagnosis time to 6.7 mm/L at the final follow-up. CRP of 3 active hip tubercular cases decreased from 80.01 mg/L (range, 37.34-136.92 mg/L) at diagnosis time to 1.91 mg/L (range, 1.05-2.57 mg/L) at the final follow-up. The ESR and CRP of all patients had returned to normal level at the final follow-up. No prosthesis dislocation, loosening and neurovascular injury was found. CONCLUSIONS: THA is an effective and safe option for hip tuberculosis. The essentials for good outcome include early diagnosis, regular perioperative anti-tubercular chemotherapy, radical debridement of inflamed tissue and necrotic bone, staged-operation if necessary.
Subject(s)
Arthroplasty, Replacement, Hip , Tuberculosis , C-Reactive Protein , Humans , Radiography , Retrospective Studies , Treatment Outcome , Tuberculosis/drug therapyABSTRACT
BACKGROUND: Osteoarthritis (OA), as a common disease, seriously affects the quality of life of the victims, but its pathogenesis remains unclear. It has been confirmed that hypoxia-induced factor (HIF)-mediated hypoxia response plays an important role in the development and progression of OA. As a member of the N-myc downstream regulatory gene families, NDRG3 has been reported to independently regulate the hypoxic response of tumour cells, but the relationship between NDRG3 and OA development has not been reported so far. METHODS: In this study, seven OA patients were admitted to Guizhou Provincial People's Hospital from January 2017 to December 2018. The OA group included 5 patients clinically diagnosed with hip/knee OA, which required arthroplasty. The normal group included 2 patients with no previous history of OA and rheumatoid arthritis, which required amputation due to trauma or tumour. The articular cartilage samples were collected to detect the expression of HIF-1α, HIF-2α and NDRG3 using immunohistochemical (IHC), haematoxylin and eosin (HE) and toluidine blue (TB) staining. RESULTS: HE and TB staining indicated that the cartilage surface of the normal group was smooth and intact, with a columnar arrangement of hyaline chondrocytes, while the cartilage surface of the OA group was discontinuous, with cartilage missing and fibrous soft tissue growing into the defect site. HIF-1α staining was positive in both groups. Moreover, HIF-2α and NDRG3 staining was weakly positive in the normal group, but were uniformly and strongly positive in the OA group. The positively stained areas and integral optical density for NDRG3 were significantly greater in OA group than in the normal group (p < 0.05). CONCLUSIONS: NDRG3 might be closely related to the development and progression of OA. However, the relationship between NDRG3 and OA, which is independent of the HIF pathway, warrants further research.
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Methacrylated gelatin (GelMA)/bacterial cellulose (BC) composite hydrogels have been successfully prepared by immersing BC particles in GelMA solution followed by photo-crosslinking. The morphology of GelMA/BC hydrogel was examined by scanning electron microscopy and compared with pure GelMA. The hydrogels had very well interconnected porous network structure, and the pore size decreased from 200 to 10 µm with the increase of BC content. The composite hydrogels were also characterized by swelling experiment, X-ray diffraction, thermogravimetric analysis, rheology experiment and compressive test. The composite hydrogels showed significantly improved mechanical properties compared with pure GelMA. In addition, the biocompatility of composite hydrogels were preliminarily evaluated using human articular chondrocytes. The cells encapsulated within the composite hydrogels for 7 days proliferated and maintained the chondrocytic phenotype. Thus, the GelMA/BC composite hydrogels might be useful for cartilage tissue engineering.
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BACKGROUND: During Kirschner wire osteosynthesis for phalangeal, metacarpal and distal radial fractures, a key clinical decision is whether to leave a Kirschner wire exposed or bury it beneath the skin. Therefore, we conducted a meta-analysis to evaluate the clinical effect of buried and exposed Kirschner wire osteosynthesis on phalangeal, metacarpal and distal radial fractures. METHODS: PubMed, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched and clinical trials that evaluated buried and exposed Kirschner wire osteosynthesis for phalangeal, metacarpal and distal radial fractures were identified. Methodological qualities of studies were assessed by using the Cochrane Collaboration tool and Newcastle-Ottawa Scale. Publication bias was detected using Begg's test and Egger's test. Sensitivity analyses were performed by excluding one study at a time to determine whether overall results were reliable. RESULTS: Two randomized controlled trials (RCT) and five case-controlled studies involving 1446 patients were included in the analysis. Sensitivity analyses indicated that the results of each study were statistically robust. Begg's test or Egger's test revealed no significant publication bias. Our meta-analysis indicated that exposed Kirschner wire osteosynthesis had a significantly higher infection rate than its buried counterpart. Additionally, buried Kirschner wire osteosynthesis resulted in a significantly higher rate of Kirschner wire removal in operating room than the exposed one. Our meta-analysis exhibited no statistical differences between the two procedures in the rate of early pin removal. CONCLUSIONS: Meta-analysis of available RCTs and case-controlled studies demonstrated that buried Kirschner wire osteosynthesis had a lower infection rate but tended to lead to more frequent Kirschner wire removal in the operating room as compared to its exposed counterpart. TRIAL REGISTRATION: PROSPERO (CRD42018105249).
ABSTRACT
OBJECTIVE: To explore the feasibility of implanting a self-designed reusable double-cavity bone harvest chamber into Guizhou mini-pigs for observation of the osteogenic effect of human bone morphogenetic protein-2 (hBMP-2) gene-activated nano bone putty on bone in growth. METHODS: Eight healthy 12-month-old female Guizhou mini-pigs were used for the present experiment. In the first operation, empty double-cavity bone harvest chambers (n = 8) were implanted into the femoral metaphysis of the animals as a blank control group. In the second operation, the femoral metaphyses were implanted with the chambers filled by the nano bone putty+hBMP-2 plasmid in one cavity and nothing in the other cavity, respectively (experiment group, n = 8). The time interval between every operation was 3 months. The cavity materials were retrieved and replaced for assessment by gross observation, histological examination, and bone morphology metrology analysis to compare osteogenesis ability and alkaline phosphatase. RESULTS: Three months after surgery, the nano bone putty+hBMP-2 plasmid in one cavity of the chambers had hard gray and white tissues inside, while the cavities pre-installed with nothing were filled with soft brown tissues. Light microscopy showed new generated bone tissue around the filled material, but only fibrous tissues in the empty cavities. Osteogenesis ability and alkaline phosphatase of the nano bone putty+hBMP-2 plasmid group were significantly higher than those of the blank control group (P < 0.05). CONCLUSION: The reusable double-cavity bone harvest chamber can be used to observe the osteogenic potential of the hBMP-2 gene-activated nano bone putty.
