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Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is meaningful but challenging. Herein, a robust three dimensional (3D) hollow CoSe2@ultrathin MoSe2 core@shell heterostructure (CoSe2@MoSe2) is proposed as an efficient HER electrocatalyst through interfacial engineering. Benefitting from the abundant heterogeneous interfaces on CoSe2@MoSe2, the exposed edge active sites are maximized and the charge transfer at the hetero-interfaces is accelerated, thus facilitating the HER kinetics. It exhibits remarkable performance in pH-universal conditions. Notably, it only needs an overpotential (η10) of 108 mV to reach a current density of 10 mA·cm−2 in 1.0 M KOH, outperforming most of the reported transition metal selenides electrocatalysts. Density functional theory (DFT) calculations unveil that the heterointerfaces synergistically optimize the Gibbs free energies of H2O and H* during alkaline HER, accelerating the reaction kinetics. The present work may provide new construction guidance for rational design of high-efficient electrocatalysts.

Integrating thermodynamic cycles with SOFCs is an effective technology to make full use of energy, but the difficulty lies in selecting the optimum thermodynamic cycles and integration scheme. The performance of a thermodynamic cycle is directly determined by the working fluid and operating parameters, and the heat exchange network (HEN) synthesis scheme directly affects the heat coupling degree and the economic performance. Therefore, a multi-objective optimization model is proposed in this paper, where the working fluid and operating parameters of the closed cycle, as well as the HEN synthesis scheme are selected as decision variables, while the total exergy destruction (TED) and the total annual cost (TAC) are adopted as the objectives. To solve this complex problem, a solving strategy based on NSGA-II with two levels is proposed to obtain the Pareto Frontier of TED and TAC. Finally, a case is solved and three Pareto optimality are analyzed and compared.

Aim This study assessed the trends in the age at menarche in Chinese schoolgirls from the majority Han group and 21 ethnic minorities from 2005 to 2014. We also compared the group differences during the study period. Methods A total of 344 230 girls aged 9-18 years were extracted from the 2005, 2010 and 2014 Chinese National Survey on Students' Constitution and Health. The age at menarche for each subgroup was estimated by probit analysis. The chi-square test and Z-test were used to compare the differences between the groups. Results The overall average age at menarche in Chinese schoolgirls decreased from 12.8 years in 2005 to 12.3 years in 2014. The Han girls and girls from 17 ethnic minorities showed decreasing trends in the age at menarche, while four ethnic minorities demonstrated fluctuating increasing trends over time. The gaps in age at menarche between the Han group and 14 of the ethnic minorities became smaller over the study period and were similar by 2014. Conclusion The overall findings were a decrease in the age at menarche in China and smaller gaps between the majority Han group and ethnic minority groups. Ethnic-specific public health policies are urgently needed on issues such as contraception.

We sought to examine changes in regional and sex disparities in stunting, thinness, and overweight among Chinese school-aged children from 1985 to 2014. We analyzed data on 1,489,953 children aged 7–18 years in the Chinese National Survey on Students’ Constitution and Health. Stunting, thinness, and overweight were defined according to WHO anthropomorphic definitions. After adjustment for age, socioeconomic status, and school, logistic regression was used to estimate the prevalence of stunting, thinness, and overweight by region and sex over 30 years’ time. From 1985 to 2014, the prevalence of stunting progressively decreased from 16.4% in 1985 to 2.3% in 2014, thinness prevalence also declined overtime, from 8.4 to 4.0% and overweight prevalence continually increased from 1.1% in 1985 to 20.4% in 2014 in Chinese school-aged children. Stunting and thinness were more common in rural areas, although urban/rural differences declined over time. Overweight was a greater problem in urban than rural areas, and this difference increased over time. Some provinces showed high levels of stunting, thinness, and overweight. The stunting prevalence of boys was higher than girls from 1985 and 1995, but lower than girls for the past 15 years. Thinness was consistently more common in boys than girls across regions and time. Overweight continuously increased for boys and girls; however, the increase was more rapid in boys. Over the past 30 years, Chinese children have shifted in anthropomorphic measures indicating a shift from problems of under-nutrition to measures consistent with over-nutrition, particularly in urban areas and among boys. Some regions are burdened by problems of both under- and over-nutrition. Regional and sex-specific guidelines and public health policies for childhood nutrition are needed in China.

Exploring low-cost and earth-abundant catalyst to efficiently release clean H2 from solid hydrogen storage materials is an appealing solution for exhausted fossil fuel and its associated environmental issue. Halloysite (Hal) nanotubes are regarded as promising alternative catalyst support for expensive synthetic support materials due to their low cost and abundant resource. Herein, we report a simple and controllable one-pot reaction followed by chemical reduction approach to manufacture Ni, Co, P hybrids on Hal as high-efficient and non-noble metal catalysts for hydrolysis of ammonia borane (AB). It is revealed that ultrafine Ni0.13Co0.87P nanoparticles with diameter of 1.4 nm are homogenously anchored on Hal surface with excellent stability. The synergy among Ni, Co and P in Ni0.13Co0.87P effectively enhances their interaction with AB, resulting in reduced activation energy (41.8 kJ mol−1) and consequently significant boost of hydrolytic catalytic activity (TOF 47.5 molH2 molcat−1 min−1). A proposed mechanism demonstrates water molecules involve in the hydrolysis reaction and the rate-determining step is the O H cleavage in H2O. This work affords a prospective idea for the exploiting of Hal as well as new point of view for the reasonable design of low-cost AB hydrolysis catalyst.

We sought to examine changes in regional and sex disparities in stunting, thinness, and overweight among Chinese school-aged children from 1985 to 2014.We analyzed data on 1,489,953 children aged 7-18 years in the Chinese National Survey on Students' Constitution and Health. Stunting, thinness, and overweight were defined according to WHO anthropomorphic definitions. After adjustment for age, socioeconomic status, and school, logistic regression was used to estimate the prevalence of stunting, thinness, and overweight by region and sex over 30 years' time.From 1985 to 2014, the prevalence of stunting progressively decreased from 16.4% in 1985 to 2.3% in 2014, thinness prevalence also declined overtime, from 8.4 to 4.0% and overweight prevalence continually increased from 1.1% in 1985 to 20.4% in 2014 in Chinese school-aged children. Stunting and thinness were more common in rural areas, although urban/rural differences declined over time. Overweight was a greater problem in urban than rural areas, and this difference increased over time. Some provinces showed high levels of stunting, thinness, and overweight. The stunting prevalence of boys was higher than girls from 1985 and 1995, but lower than girls for the past 15 years. Thinness was consistently more common in boys than girls across regions and time. Overweight continuously increased for boys and girls; however, the increase was more rapid in boys.Over the past 30 years, Chinese children have shifted in anthropomorphic measures indicating a shift from problems of under-nutrition to measures consistent with over-nutrition, particularly in urban areas and among boys. Some regions are burdened by problems of both under- and over-nutrition. Regional and sex-specific guidelines and public health policies for childhood nutrition are needed in China.