A facile Mn surface doping process is proposed to improve the thermal and structural stabilities of Ni-rich layered cathode materials (Ni ≥ 80%) for lithium-ion batteries in electric vehicles. ...Herein, we demonstrate that the surface structure of the Ni-rich layered cathode materials can be stabilized by the introduction of a thin Mn-rich surface layer. This layer effectively reduces the direct exposure of the highly reactive Ni on the surface of the cathode materials, thus enhancing thermal stability and mitigating side reactions associated with highly reactive Ni that causes the loss of reversible capacity. In practice, the Mn surface-doped Ni-rich layered cathode material exhibits a high specific capacity with an improved cycling stability even at a high temperature (60 °C). We believe that our simple approach offers more opportunities to upscale production without any extra caution.
The Aurivillius phases of complex bismuth oxides have attracted considerable attention because of their lattice polarization (ferroelectricity) and photocatalytic activity. We report a ...first-principles exploration of Bi2WO6 and the crystal engineering through replacing W6+ by pentavalent (Nb5+ and Ta5+) and tetravalent (Ti4+ and Sn4+) ions, with charge neutrality maintained by the formation of a mixed anion oxyhalide sublattice. We find that Bi2SnO4F2 is thermodynamically unstable, in contrast to Bi2TaO5F, Bi2NbO5F, and Bi2TiO4F2. The electric dipoles introduced by chemical substitutions in the parent compound are found to suppress the spontaneous polarization from 61.55 μC/cm2 to below 15.50 μC/cm2. Analysis of the trends in electronic structure, surface structure, and ionization potentials is reported. This family of materials can be further extended with control of layer thicknesses and choice of compensating halide species.
Polytypes formed during the growth of metal halide perovskites can give rise to the formation of face-sharing sequences in corner-sharing octahedral networks. Here, the electronic influences of such ...structures, including the 6H and 12R phases, are found to be correlated with the fraction and stacking sequence of the face-sharing layers. The band gaps of polytypes feature a characteristic evolution from indirect to direct from pure hexagonal (2H) to cubic (3C) phases. Rather than arising from orbital mixing at the atomic level, a large band gap bowing of 1.96 eV in the CsPbI3 family was attributed to the long-range electronic interaction between octahedral building blocks. While retaining a high carrier velocity (∼2 × 105 m s–1), Fermi surface analysis further revealed a decrease of dimensionality from 3D to 2D in frequently observed polytypes, indicating a carrier blocking and anisotropic transport effect of hexagonal impurity phases, with consequences for their applications in solar cells and other optoelectronic devices.
Background
The survival paradox between stage IIB/C (T4N0) and stage IIIA (T1-2N1) colon cancer remains in the 7th edition of the American Joint Committee on Cancer staging system. This multicenter ...study aimed to compare the oncologic outcomes of T4N0 and T1-2N1 colon cancers and to investigate the presumptive prognostic factors that might influence the survival paradox.
Methods
Patients who underwent curative surgery for pT4N0 (
n
= 224) and pT1-2N1 (
n
= 135) primary colon cancer between January 1999 and December 2010 at five tertiary referral cancer centers were included for analysis. The clinicopathologic, treatment-related factors, and oncologic outcomes in terms of the 5-year overall survival (5-OS) and 5-year disease-free survival (5-DFS) were compared.
Results
The T4N0 group had significantly worse 5-OS and 5-DFS rates than the T1-2N1 group (5-OS: 84.0 vs. 92.3 %,
p
= 0.012; 5-DFS: 73.6 vs. 88.0 %,
p
= 0.001). T4N0 cancers more frequently showed elevated preoperative carcinoembryonic antigen, lower grade of differentiation, larger tumor size, and higher proportions of perineural invasion, microsatellite instability, obstruction, and perforation than T1-2N1 cancers. Peritoneal seeding and liver metastasis were the predominant recurrence pattern in the T4N0 and T1-2N1 groups, respectively (
p
= 0.042). The T4N0 group showed inferior survival to the T1-2N1 group in postoperative adjuvant chemotherapy (5-OS: 87.1 vs. 93.2 %,
p
= 0.045; 5-DFS: 76.1 vs. 89.0 %,
p
= 0.001).
Conclusions
T4N0 colon cancer had significantly worse oncologic outcomes than T1-2N1 cancer regardless of adjuvant chemotherapy. The survival paradox may result from the biologic aggressiveness of T4N0 colon carcinomas.
As the demand for various electronic devices using the advantages of lithium ion batteries (LIBs) increases, the disposal of LIBs has also been an important issue. We synthesize LiNi1/3Mn1/3Co1/3O2 ...(NMC) and LiNi1/3Mn1/3Co1/3AlxO2 (NMCA) cathode active materials with various amounts of Al (NMCA (x%)) via hydroxide coprecipitation and calcination processes, which simulates the resynthesis of NMC in leachate containing Al from spent LIBs. The effects of Al on the physicochemical, thermal and electrochemical (initial charge/discharge capacity, cyclability and rate capability) properties of NMCA are investigated and compared with NMC. An increase in the Al content in NMCA incurs an irregular shape and the uneven distribution of active material particles as confirmed by scanning electron microscope. The initial charge/discharge capacity and cyclability deteriorate as the Al content increases. The capacity retention of NMCA (2.00%) starts to decline rapidly at an earlier cycle than the other NMCA samples. On the other hand, the rate capability of NMCA is enhanced and electrochemical impedance spectroscopy analysis shows that NMCA (2.00%) has a higher lithium ion diffusion coefficient than NMC. Overall, residual Al in the cathode active materials has an adverse effect on capacity and cyclability, which could be tolerated with traces of Al less than 0.05% in NMCA.
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•Effects of Al in NiMnCo oxide on its Li-ion battery performance are investigated.•Capacity and cycleability of Li NiMnCo oxide (NMC) deteriorate by Al addition.•Li-ion diffusion and rate capability are enhanced by Al addition.•It is desirable to remove Al to the level of 0.05% in the resynthesis of NMC.
In this study, we analyzed seed germination, seedling growth, and physiological aspects after treatment with high voltage nanosecond pulsed plasma and micro DBD plasma in spinach (Spinacia oleracea ...L.), a green leafy vegetable known to have low germination rate. Both germination and dry weight of seedlings increased after high voltage pulse shots were applied to spinach seeds. However seeds treated with many shots (10 shots) showed a decrease in germination rate and seedling growth. Seeds treated with air DBD plasma exhibited slightly higher germination and subsequent seedling growth than those treated with N2 plasma. Seed surface was degenerated after treated with high voltage pulsed plasma and micro DBD plasma but no significant difference in the degree of degeneration was observed among micro DBD plasma treatment time. Level of GA3 hormone and mRNA expression of an amylolytic enzyme-related gene in seeds were elevated 1 day after treatment with high voltage pulsed plasma. The relative amount of chlorophyll and total polyphenols in spinach seedlings grown from seeds treated with air DBD plasma was increased in 30 s, 1 min, and 3 min treatments. Taken together, our results suggest a possibility that plasma can enhance seed germination by triggering biochemical processes in seeds.
•Development of spinach was enhanced by high voltage nanosecond pulsed plasma.•Micro DBD air plasma slightly promoted spinach seed germination and growth.•Plasma can enhance plant development by activating biochemical events inside seed.
The formation of stacking faults and polytypes in
ZnSnN
2
,
ZnGeN
2
, and
ZnSiN
2
was investigated by the first-principles density functional theory calculations. To analyze the interactions between ...the layers of polytypes, we constructed an anisotropic next-nearest neighbor interaction model that reproduced the DFT fitted total energies. Our calculation showed that the stacking fault energy is around 0.28 eV/nm
2
, indicating that the planar defect is expected to be formed in
ZnSnN
2
. The formation of stacking faults can be suppressed by replacing Sn with Si. Stacking faults produce a sawtooth-like potential due to polarization charge, resulting in the separation of electron and hole carriers.
Background
Maintaining cerebral blood flow is important in intraoperative management of moyamoya disease patients.
Aims
To access changes in the carotid artery blood flow velocity in response to ...fluid challenge, blood pressure, and cardiac output under general anesthesia in pediatric patients with moyamoya disease.
Methods
This observational study included pediatric patients with moyamoya disease undergoing general anesthesia for encephaloduroarteriosynangiosis. Each patient underwent an ultrasound assessment thrice as follows: after anesthetic induction (T1), after fluid challenge (10 ml/kg, T2), and at the end of surgery (T3). The primary outcome was the change in the internal carotid artery blood flow velocity after fluid challenge and was assessed using a paired t‐test. The secondary outcomes comprised changes in the internal, external, and common carotid artery blood flow peak velocities after fluid challenge and the factors influencing these changes.
Results
We enrolled and analyzed 30 patients with a mean age of 7.2 years. After fluid challenge, the systolic (p = .003) and mean blood pressure (p = .017), stroke volume index (p = .008), and cardiac index (p = .140) were higher than those at T1. However, both internal carotid artery blood flow velocities did not change after fluid challenge (p = .798, mean difference and 95% confidence interval CI, −1.1 and −10.3 to 8.0 for right, p = .164, mean difference and 95% CI, −5.2 and −12.7 to 2.2 for left). The internal carotid artery blood flow velocity was correlated with the cardiac index, stroke volume index, and mean and diastolic blood pressure, with low significance.
Conclusions
The internal carotid artery blood flow velocity did not increase in pediatric patients with moyamoya disease under general anesthesia, despite fluid challenge and corresponding changes in the blood pressure and cardiac output. Intraoperative hemodynamic management to improve the cerebral blood flow in these patients requires further investigation.
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