Lithium-oxygen (Li-O) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decomposition and Li dendrite growth. This suppression is attributed to thermodynamic properties of the electrochemically active lithium phosphide protective layer. The electrolyte decomposition is suppressed on the protective layer because the redox potential of lithium phosphide layer is higher than that of electrolyte decomposition. Li plating is thermodynamically unfavorable on lithium phosphide layers, which hinders Li dendrite growth during cycling. As a result, the nanosized lithium phosphide protective layer improves the cycle performance of Li symmetric cells and Li-O batteries with various electrolytes including lithium bis(trifluoromethanesulfonyl)imide in N,N-dimethylacetamide. A variety of ex situ analyses and theoretical calculations support these behaviors of the phosphorene-derived lithium phosphide protective layer.

Epidemiological research has convincingly shown that obesity increases colorectal cancer (CRC) risk, with generally stronger associations observed in men than in women. Evidence from the past several years has demonstrated a divergent pattern between men and women regarding the weight changes throughout life or timing of obesity for CRC risk. For men, weight gain later in life appears to be an important risk factor for CRC that mostly accounts for their generally strong association between adult body mass index and CRC risk. For women, however, early life obesity seems to be more important than adult weight gain in determining CRC risk. A knowledge of these sex patterns may have implications on better understanding colorectal carcinogenesis and may further improve prevention efforts for CRC.

Ni-rich layered oxide materials have been considered as promising cathode materials for high energy density Li-ion batteries because of their high reversible capacity. One of their catastrophic failure modes is the formation of residual lithium compounds on the oxide surface when it is exposed to air. In this paper, it is demonstrated that water is essential for the formation of residual lithium at room temperature. Furthermore, hydrophobic LiNi 0.8 Co 0.1 Mn 0.1 O 2 is introduced to suppress the formation of residual lithium because the hydrophobic surface inhibits contact between water and LiNi 0.8 Co 0.1 Mn 0.1 O 2 . Hydrophobic LiNi 0.8 Co 0.1 Mn 0.1 O 2 is obtained through surface engineering using hydrophobic organic molecules, such as polydimethylsiloxane. Hydrophobic polydimethylsiloxane-grafted LiNi 0.8 Co 0.1 Mn 0.1 O 2 suppresses the formation of residual lithium even in humid air, leading to the negligible surface degradation of LiNi 0.8 Co 0.1 Mn 0.1 O 2 . As a result, hydrophobic LiNi 0.8 Co 0.1 Mn 0.1 O 2 shows excellent electrochemical performance even after storage in humid air for 2 weeks.

Various doped materials have been investigated to improve the structural stability of layered transition metal oxides for lithium‐ion batteries. Most doped materials are obtained through solid state methods, in which the doping of cations is not strictly site selective. This paper demonstrates, for the first time, an in situ electrochemical site‐selective doping process that selectively substitutes Li+ at Li sites in Mn‐rich layered oxides with Mg2+. Mg2+ cations are electrochemically intercalated into Li sites in delithiated Mn‐rich layered oxides, resulting in the formation of [Li1−xMgy][Mn1−zMz]O2 (M = Co and Ni). This Mg2+ intercalation is irreversible, leading to the favorable doping of Mg2+ at the Li sites. More interestingly, the amount of intercalated Mg2+ dopants increases with the increasing amount of Mn in Li1−x[Mn1−zMz]O2, which is attributed to the fact that the Mn‐to‐O electron transfer enhances the attractive interaction between Mg2+ dopants and electronegative Oδ− atoms. Moreover, Mg2+ at the Li sites in layered oxides suppresses cation mixing during cycling, resulting in markedly improved capacity retention over 200 cycles. The first‐principle calculations further clarify the role of Mg2+ in reduced cation mixing during cycling. The new concept of in situ electrochemical doping provides a new avenue for the development of various selectively doped materials.

BACKGROUND & AIMS: Vitamin D has been implicated in colorectal cancer (CRC) pathogenesis, but it remains unknown whether total vitamin D intake is associated with early-onset CRC and precursors diagnosed before age 50. METHODS: We prospectively examined the association between total vitamin D intake and risks of early-onset CRC and precursors among women enrolled in the Nurses' Health Study II. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for early-onset CRC were estimated with Cox proportional hazards model. Multivariable-adjusted odds ratios (ORs) and 95% CIs for early-onset conventional adenoma and serrated polyp were estimated with logistic regression model. RESULTS: We documented 111 incident cases of early-onset CRC during 1,250,560 person-years of follow-up (1991 to 2015). Higher total vitamin D intake was significantly associated with a reduced risk of early-onset CRC (HR for !450 IU/day vs <300 IU/day, 0.49; 95% CI, 0.26-0.93; P for trend ¼ .01). The HR per 400 IU/day increase was 0.46 (95% CI, 0.26-0.83). The inverse association was significant and appeared more evident for dietary sources of vitamin D (HR per 400 IU/day increase, 0.34; 95% CI, 0.15-0.79) than supplemental vitamin D (HR per 400 IU/day increase, 0.77; 95% CI, 0.37-1.62). For CRC precursors, the ORs per 400 IU/day increase were 0.76 (95% CI, 0.65-0.88) for conventional adenoma (n ¼ 1,439) and 0.85 (95% CI, 0.75-0.97) for serrated polyp (n ¼ 1,878). CONCLUSIONS: In a cohort of younger women, higher total vitamin D intake was associated with decreased risks of early-onset CRC and precursors.

Dietary fibre is believed to provide important health benefits including protection from colorectal cancer. However, the evidence on the relationships with different dietary fibre sources is mixed and little is known about which fibre source provides the greatest benefits. We conducted a dose–response meta-analysis of prospective cohorts to summarise the relationships of different fibre sources with colorectal cancer and adenoma risks. Analyses were restricted to publications that reported all fibre sources (cereals, vegetables, fruits, legumes) to increase comparability between results. PubMed and Embase were searched through August 2018 to identify relevant studies. The summary relative risks (RR) and 95 % CI were estimated using a random-effects model. This analysis included a total of ten prospective studies. The summary RR of colorectal cancer associated with each 10 g/d increase in fibre intake were 0·91 (95 % CI 0·82, 1·00; I2 = 0 %) for cereal fibre, 0·95 (95 % CI 0·87, 1·03, I2 = 0 %) for vegetable fibre, 0·91 (95 % CI 0·78, 1·06, I2 = 43 %) for fruit fibre and 0·84 (95 % CI 0·63, 1·13, I2 = 45 %) for legume fibre. For cereal fibre, the association with colorectal cancer risk remained statistically significant after adjustment for folate intake (RR 0·89, 95 % CI 0·80, 0·99, I2 = 2 %). For vegetable and fruit fibres, the dose–response curve suggested evidence of non-linearity. All fibre sources were inversely associated with incident adenoma (per 10 g/d increase: RR 0·81 (95 % CI 0·54, 1·21) cereals, 0·84 (95 % CI 0·71, 0·98) for vegetables, 0·78 (95 % CI 0·65, 0·93) for fruits) but not associated with recurrent adenoma. Our data suggest that, although all fibre sources may provide some benefits, the evidence for colorectal cancer prevention is strongest for fibre from cereals/grains.

Na-ion batteries are attractive as an alternative to Li-ion batteries because of their lower cost. Organic compounds have been considered as promising electrode materials due to their environmental friendliness and molecular diversity. Herein, aluminum-coordinated poly(tetrahydroxybenzoquinone) (P(THBQ-Al)), one of the coordination polymers, is introduced for the first time as a promising cathode for Na-ion batteries. P(THBQ-Al) is synthesized through a facile coordination reaction between benzoquinonedihydroxydiolate (COH) and Al as ligands and complex metal ions, respectively. Tetrahydroxybenzoquinone is environmentally sustainable, because it can be obtained from natural resources such as orange peels. Benzoquinonedihydroxydiolate also contributes to delivering high reversible capacity, because each benzoquinonedihydroxydiolate unit is capable of two electron reactions through the sodiation of its conjugated carbonyl groups. Electrochemically inactive Al improves the structural stability of P(THBQ-Al) during cycling because of a lack of a change in its oxidation state. Moreover, P(THBQ-Al) is thermally stable and insoluble in nonaqueous electrolytes. These result in excellent electrochemical performance including a high reversible capacity of 113 mA h g and stable cycle performance with negligible capacity fading over 100 cycles. Moreover, the reaction mechanism of P(THBQ-Al) is clarified through ex situ XPS and IR analyses, in which the reversible sodiation of C═O into C-O-Na is observed.

LiNiO 2 is a promising cathode material for lithium ion batteries because of its high specific capacity (approximately 220 mA h g −1 ). However, there are several challenging issues in the development of LiNiO 2 , including its poor cycle and rate performance because of its structural deterioration due to thermodynamically unstable Ni 3+ . This paper demonstrates the role of Na + in the electrochemical performance and structural stability of [Li 1-x Na x ]NiO 2 (x = 0, 0.005, 0.01, 0.025, and 0.05). Charge disproportionation Ni 3+ → Ni 2+ and Ni 4+ in LiNiO 2 increases the cation mixing of Li + and Ni 2+ during cycling, resulting in the poor cycle performance of LiNiO 2 . However, Na + in [Li 1-x Na x ]NiO 2 mitigates the charge disproportionation because of the larger size of Na + than Li + , leading to the improved structural stability of [Li 1-x Na x ]NiO 2 . Consequently, Na + -doped LiNiO 2 alleviates the increase in the cation mixing of Li + and Ni 2+ during cycling compared to bare LiNiO 2 . This results in the improved cycle performance of [Li 1-x Na x ]NiO 2 (x = 0.05), such as approximately 76% of capacity retention after 100 cycles. Moreover, the substitution of Li + with Na + in LiNiO 2 improves the storage characteristics of [Li 1-x Na x ]NiO 2 , leading to a negligible capacity loss even after long-term storage.