No abstract

Micron-sized truncated octahedral LiNi 0.5 Mn 1.5 O 4 (LNMO) samples with different degrees of Ni/Mn disordering have been obtained by controlling the synthesis conditions, such as calcination atmosphere (O 2 and air), cooling rate or additional annealing step. The influences of Ni/Mn disordering on the physical properties and electrochemical performance of the truncated octahedral LNMO samples have been systematically investigated. The analyses of thermogravimetry, X-ray photoelectron spectroscopy, X-ray diffraction, powder neutron diffraction, Raman spectroscopy and X-ray absorption spectroscopy reveal that the occurrence and degree of Ni/Mn disordering are closely related with the formation of oxygen vacancies and presence of Mn 3+ . Slow cooling rate and post-annealing can result in low degrees of Ni/Mn disordering and oxygen vacancies. Electrochemical measurements show that Ni/Mn disordering and oxygen vacancies have no obvious effect on the rate capability since all LNMO samples share a truncated octahedral morphology with the exposed {100} surfaces. However, they play significant roles in improving long-term cycling stability, especially at the elevated temperature of 60 • C. This work suggests that the electrochemical performance of LNMO with optimized truncated morphology can be further enhanced through tuning the degrees of Ni/Mn disordering and oxygen vacancies.

ObjectiveTo retrospectively compare the efficacy of the titanium mesh cage (TMC) and the nano-hydroxyapatite/polyamide66 cage (n-HA/PA66 cage) for 1- or 2-level anterior cervical corpectomy and fusion (ACCF) to treat multilevel cervical spondylotic myelopathy (MCSM).MethodsA total of 117 consecutive patients with MCSM who underwent 1- or 2-level ACCF using a TMC or an n-HA/PA66 cage were studied retrospectively at a mean follow-up of 45.28±12.83 months. The patients were divided into four groups according to the level of corpectomy (1- or 2-level corpectomy) and cage type used (TMC or n-HA/PA66 cage). Clinical and radiological parameters were used to evaluate outcomes.ResultsAt the one-year follow-up, the fusion rate in the n-HA/PA66 group was higher, albeit non-significantly, than that in the TMC group for both 1- and 2-level ACCF, but the fusion rates of the procedures were almost equal at the final follow-up. The incidence of cage subsidence at the final follow-up was significantly higher in the TMC group than in the n-HA/PA66 group for the 1-level ACCF (24% vs. 4%, p = 0.01), and the difference was greater for the 2-level ACCF between the TMC group and the n-HA/PA66 group (38% vs. 5%, p = 0.01). Meanwhile, a much greater loss of fused height was observed in the TMC group compared with the n-HA/PA66 group for both the 1- and 2-level ACCF. All four groups demonstrated increases in C2-C7 Cobb angle and JOA scores and decreases in VAS at the final follow-up compared with preoperative values.ConclusionThe lower incidence of cage subsidence, better maintenance of the height of the fused segment and similar excellent bony fusion indicate that the n-HA/PA66 cage may be a superior alternative to the TMC for cervical reconstruction after cervical corpectomy, in particular for 2-level ACCF.