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Introduction: In an anterior cervical discectomy and fusion (ACDF), various types of graft materials including autograft, allograft, and synthetic graft have been used to achieve adequate spinal fusion. Allograft spacer is mainly used in cervical fusion, especially in the anterior approach. The synthetic bone graft material BGS-7(CaO-SiO2-P2O5-B2O3, bioactive Glass-Ceramics) can bind with surrounding bone tissue by forming a hydroxyapatite layer bone bridge, leading to faster graft osseointegration. This study was conducted to compare long-term clinical outcome of BGS-7 spacer and allograft spacer for anterior cervical discectomy and fusion surgery. Materials and Methods: From September 2014 to December 2016, Consecutive anterior cervical discectomy and fusion surgeries using a BGS-7 spacer (N = 18) and Allograft spacer (N = 26) were compared for postoperative clinical outcomes. Radiologic assessments were performed, and Instrumental failure, including breakage, cage migration, subsidence were observed and Fusion status were analyzed. Finite element analysis was performed for simulating mechanical stress between the vertebral body and implant. Clinical outcomes were evaluated using neck VAS, NDI, and JOA on the patient’s final follow-up visits. Results: Among the 44 patients who underwent an anterior cervical discectomy and fusion surgery using the BGS-7 spacer and Allograft spacer, there were 30 men and 14 women. The average age at the operation was 47.69 ± 10.49 in allograft spacer and 51.67 ± 11.03 in BGS-7 spacer. The mean follow-up period was 89.18 ± 5.44 months. Twenty three (88.46%) patients in allograft spacer and 20(100%) patients in BGS-7 spacer were demonstrated radiologic evidence of interbody fusion in last OPD, which accounts for fusion grade 4 or 5. Peak stresses were 343.85 MPa in allograft spacer, and 132.55 MPa in BGS-7 spacer. Long-term clinical outcomes including neck VAS, NDI, and JOA didn’t show statistical differences between the two groups. There were no adverse events related to the BGS-7 spacer.10.3389/fbioe.2023.110046. Conclusion: The BGS-7 spacer demonstrated reliability as a spacer in anterior cervical discectomy and fusionF surgery without instrumental failure. Early stabilization with a bony bridge formation was observed at the intermediate follow-up period, and the long-term clinical outcome was favorable at more than 60 months after surgery without any adverse events. Thus, the BGS-7 spacer is a safe and effective alternative to the allograft spacer in anterior cervical discectomy and fusion surgery.

This article aimed to assess the efficacy of surgical treatments, particularly arthrodesis with C2 nerve transection, in patients with atlantoaxial osteoarthritis (AAOA). Data of patients with AAOA who underwent surgical treatment between January 2020 and November 2023 were retrospectively collected. Of 11 patients with AAOA, nine underwent fusion surgery, and two underwent decompression surgery. C2 root transection on the symptomatic side was performed in all fusion cases. C2 root transection was not performed during decompression. All patients experienced immediate and persistent pain relief after surgery. Four patients who underwent fusion surgery reported a complete disappearance of pain. Four patients who underwent fusion surgery reported some numbness of the scalp, but it did not affect the quality of daily activities or cause significant discomfort. One patient who underwent decompression surgery reported residual tingling sensation and hyperesthesia of the scalp. We concluded that C1-2 fusion surgery is an excellent surgical treatment option and should be primarily considered for patients with refractory AAOA. C2 root transection on the symptomatic side can completely alleviate pain at the expense of minor scalp anesthesia. Decompressive-only surgery is not recommended but can be considered in strictly selected patients.

PurposeNumerous factors affect the surgical outcomes in patients with adult spinal deformity (ASD). However, no study has examined the relationship between residence and physical factors and surgical outcomes in patients with ASD. Here, we analysed the impact of residence and physical factors on the post-operative outcomes of patients with ASD residing in urban (U) and rural (R) environments.MethodsWe retrospectively reviewed data from patients who had undergone ASD surgery with sacropelvic fixation at a single institution between June 2011 and May 2017 with a minimum 1 year follow-up. We divided the patients into two groups (U and R). Preoperative demographic data were reviewed, and radiographic parameters were measured preoperatively, immediately postoperatively, at 1, 3, and 6 months, and at the final follow-up. The L4 axial paraspinal muscles were measured preoperatively using magnetic resonance imaging.ResultsThere were 25 and 34 patients in the U and R groups, respectively. Both groups had similar preoperative demographic and radiological parameters. There were no differences between the groups in post-operative radiographic parameters, clinical outcomes, and complications, but proximal junctional kyphosis (PJK) was significantly higher in the R group. Additionally, muscle mass in the multifidus and erector spinae was lower in the R than in the U group.ConclusionsPatient residence influenced PJK in patients with ASD. Mass reduction in the trunk extensor muscle is an important and existing risk factor for PJK. Surgeons should be aware of this information for preoperative counselling, informed consent, and post-operative education of patients with ASD.Graphic abstractThese slides can be retrieved from Electronic Supplementary Material.

Black phosphorus consists of stacked layers of phosphorene, a two-dimensional semiconductor with promising device characteristics. We report the realization of a widely tunable band gap in few-layer black phosphorus doped with potassium using an in situ surface doping technique. Through band structure measurements and calculations, we demonstrate that a vertical electric field from dopants modulates the band gap, owing to the giant Stark effect, and tunes the material from a moderate-gap semiconductor to a band-inverted semimetal. At the critical field of this band inversion, the material becomes a Dirac semimetal with anisotropic dispersion, linear in armchair and quadratic in zigzag directions. The tunable band structure of black phosphorus may allow great flexibility in design and optimization of electronic and optoelectronic devices.

Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density1. Carrier doping to 2D semiconductors can be used to modulate many-body interactions2 and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)3–5, which has been proposed to play a key role in high-temperature superconductivity6 and carrier mobility in devices7. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS2, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently8–11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons12–18. The short-range nature of electron–phonon (e–ph) coupling in MoS2 can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.

Semiconductor devices rely on the charge and spin of electrons, but there is another electronic degree of freedom called pseudospin in a two-level quantum system 1 such as a crystal consisting of two sublattices 2 . A potential way to exploit the pseudospin of electrons in pseudospintronics 3 – 5 is to find quantum matter with tunable and sizeable pseudospin polarization. Here, we propose a bipolar pseudospin semiconductor, where the electron and hole states have opposite net pseudospin polarization. We experimentally identify such states in anisotropic honeycomb crystal—black phosphorus. By sublattice interference of photoelectrons, we find bipolar pseudospin polarization greater than 95% that is stable at room temperature. This pseudospin polarization is identified as a consequence of Dirac cones merged in the highly anisotropic honeycomb system 6 , 7 . The bipolar pseudospin semiconductor, which is a pseudospin analogue of magnetic semiconductors, is not only interesting in itself, but also might be useful for pseudospintronics. Anisotropic honeycomb crystal of black phosphorous is found to have pseudospin polarization greater than 95% at room temperature, attributed to the merging of Dirac cones. This bipolar pseudospin semiconductor may be useful for pseudospintronics.

NRC publication: Yes

Background In multilevel ossification of the posterior longitudinal ligament (OPLL), laminectomy is an effective surgical technique; however, there is a possibility of kyphotic alignment change after surgery. Nevertheless, in the continuous type of OPLL, the ossification foci are connected and may act as stabilizers preventing alignment change. We here compare the surgical outcome of laminectomy and laminoplasty in continuous-type OPLL of the cervical spine. Methods Seventy-three patients who underwent cervical laminectomy or laminoplasty for continuous-type OPLL from 2004 to 2014 were enrolled. The clinical outcomes were assessed by using the neck disability index, visual analogue scale, and Japanese Orthopedic Association scoring systems. Radiological evaluation with plain lateral radiographs was performed to observe alignment changes. Results The perioperative clinical outcome with laminectomy did not differ significantly from that of laminoplasty. Kyphotic change was observed in 3 of 35 patients with laminectomy and 3 of 38 patients with laminoplasty. Although loss of lordosis was observed in both groups, the C2–7 Cobb angle, sagittal vertical axis (SVA), and T1 slope did not demonstrate significant statistical differences between laminectomy and laminoplasty. Moreover, the C2–7 SVA in the C7-included laminectomy group (33.9 ± 13.4) became greater than that in the C7-excluded laminectomy group (24.8 ± 11.3) at the final follow-up ( p  = 0.049). Conclusions In continuous-type OPLL, the surgical outcome did not show any significant difference between laminectomy and laminoplasty. Laminectomy alone is also a good choice in continuous-type OPLL, similar to laminoplasty.

Boron nitride nanotubes (BNNTs) are emerging nanomaterials with analogous structures and similarly impressive mechanical properties to carbon nanotubes (CNTs), but unique chemistry and complimentary multifunctional properties, including higher thermal stability, electrical insulation, optical transparency, neutron absorption capability, and piezoelectricity. Over the past decade, advances in synthesis have made BNNTs more broadly accessible to the nanomaterials and other research communities, removing a major barrier to their utilization and research. Therefore, the field is poised to grow rapidly and see the emergence of BNNT applications ranging from electronics to aerospace materials. A key challenge, that is being gradually overcome, is the development of manufacturing processes to make “neat” BNNT materials. This overview highlights the history and current status of the field, providing both an introduction to this Focus Issue—BNNTs: Synthesis to Applications—as well as a perspective on advances, challenges, and opportunities for this emerging material.

High-entropy alloy (HEA) nanoparticles (NPs) exhibit unusual combinations of functional properties. However, their scalable synthesis remains a significant challenge requiring extreme fabrication conditions. Metal salts are often employed as precursors because of their low decomposition temperatures, yet contain potential impurities. Here, we propose an ultrafast (< 100 ms), one-step method that enables the continuous synthesis of HEA NPs directly from elemental metal powders via in-flight alloying. A high-temperature plasma jet ( > 5000 K) is employed for rapid heating/cooling (10³ − 10⁵ K s⁻¹), and demonstrates the synthesis of CrFeCoNiMo HEA NPs ( ~ 50 nm) at a high rate approaching 35 g h⁻¹ with a conversion efficiency of 42%. Our thermofluid simulation reveals that the properties of HEA NPs can be tailored by the plasma gas which affects the thermal history of NPs. The HEA NPs demonstrate an excellent light absorption of > 96% over a wide spectrum, representing great potential for photothermal conversion of solar energy at large scales. Our work shows that the thermal plasma process developed could provide a promising route towards industrial scale production of HEA NPs.