Comment on "Atomic Scale Structure and Chemical Composition across Order-Disorder Interfaces"

Interfaces have long been known to be the key to many mechanical and electric properties. To nickel base superalloys which have perfect creep and fatigue properties and have been widely used as materials of turbine blades, interfaces determine the strengthening capacities in high temperature. By means of high resolution scanning transmission electron microscopy (HRSTEM) and 3D atom probe (3DAP) tomography, Srinivasan et al. proposed a new point that in nickel base superalloys there exist two different interfacial widths across the {\gamma}/{\gamma}' interface, one corresponding to an order-disorder transition, and the other to the composition transition. We argue about this conclusion in this comment

Determination of incommensurate modulated structure in Bi2Sr1.6La0.4CuO6+{\delta} by aberration-corrected transmission electron microscopy

Incommensurate modulated structure (IMS) in Bi2Sr1.6La0.4CuO6+{\delta} (BSLCO) has been studied by aberration corrected transmission electron microscopy in combination with high-dimensional (HD) space description. Two images in the negative Cs imaging (NCSI) and passive Cs imaging (PCSI) modes were deconvoluted, respectively. Similar results as to IMS have been obtained from two corresponding projected potential maps (PPMs), but meanwhile the size of dots representing atoms in the NCSI PPM is found to be smaller than that in PCSI one. Considering that size is one of influencing factors of precision, modulation functions for all unoverlapped atoms in BSLCO were determined based on the PPM obtained from the NCSI image in combination with HD space description

Ultrahigh thermoelectric performance in Cu2−ySe0.5S0.5 liquid-like materials

Liquid-like thermoelectric materials have recently received heightened attentions due to their exceptional thermal and electrical transport properties. As a typical example, Cu2−ySe has good electrical transport properties while Cu2−yS has extremely low lattice thermal conductivity. Combining these stirring characters into one material is expected to result in excellent thermoelectric performance. In this study, we found that Cu2−ySe and Cu2−yS can form a solid solution in the composition range down to half Se and half S. XRD, SEM and TEM reveal that Cu2−ySe0.5S0.5 possesses a unique hierarchical microstructure composed of mesoscale polymorphs, nanoscale domains and modulations. Besides, the liquid-like copper ions at high temperature not only strongly scatter lattice phonons but also eliminate some of the transverse phonon vibrations. Combining with the extraordinarily low sound speeds, an overall ultralow thermal conductivity is achieved in Cu2−ySe0.5S0.5 with the values similar to that in Cu2S. Furthermore, the electrical transport performance of Cu2−ySe0.5S0.5 is significantly improved through tuning its native Cu vacancies. High electrical power factors similar to or even superior to Cu2−ySe are observed due to the high weighted mobility. All these favorable factors lead to much enhanced quality factor and thus remarkably high thermoelectric performance in Cu2−ySe0.5S0.5, which reaches a ZT of 2.3 at 1000 K, among the highest values in bulk materials.submittedVersionThis is a submitted manuscript of an article published by Elsevier Ltd in Materials Today Physics, 7 June 2017

A versatile route to fabricate single atom catalysts with high chemoselectivity

Preparation of single atom catalysts (SACs) is of broad interest to materials scientists and chemists but remains a formidable challenge. Herein, we develop an efficient approach to synthesize SACs via a precursor-dilution strategy, in which metalloporphyrin (MTPP) with target metals are co-polymerized with diluents (tetraphenylporphyrin, TPP), followed by pyrolysis to N-doped porous carbon supported SACs (M1/N-C). Twenty-four different SACs, including noble metals and non-noble metals, are successfully prepared. In addition, the synthesis of a series of catalysts with different surface atom densities, bi-metallic sites, and metal aggregation states are achieved. This approach shows remarkable adjustability and generality, providing sufficient freedom to design catalysts at atomic-scale and explore the unique catalytic properties of SACs. As an example, we show that the prepared Pt1/N-C exhibits superior chemoselectivity and regioselectivity in hydrogenation. It only converts terminal alkynes to alkenes while keeping other reducible functional groups such as alkenyl, nitro group, and even internal alkyne intact

Short-term lifestyle education on obesity reduction in adolescents

BackgroundsObesity is increasing in adolescents in China. However, the awareness of obesity and prevention on related risk factors were not well known. We aim to assess the effectiveness of short-term health education intervention on obesity in Chinese adolescents.MethodsIn this study, 42 primary and secondary schools from Qingdao were randomly divided into the education and control groups. A total of 11,739 adolescents was included in the current study. The logistic regression was employed to assess odds ratio (OR) of education intervention on overweight and obesity prevalence adjusting for covariates.ResultsThe baseline prevalence of overweight and obesity was significantly higher in urban than in rural areas and in boys than in girls. After 1 year lifestyle intervention, the proportion of students with awareness of obesity was higher, meanwhile age-adjusted mean values of weight, body mass index, duration of watching TV and doing homework were lower in education group than control group. The corresponding figures were 43.6 [95% CI (confidence intervals); 43.3–43.9] kg versus 44.3 (95% CI; 44.0–44.6) kg, 18.6 (95% CI; 18.5–18.7) kg/m2 versus 18.9 (95% CI; 18.8–19.1) kg/m2, 1.3 (95% CI; 1.2–1.3) hours/d versus 1.4 (95% CI; 1.3–1.4) hours/d, and 1.5 (95% CI; 1.4–1.5) hours/d versus 1.8 (95% CI, 1.7–1.8) hours/d. The multivariable adjusted OR for combined prevalence of overweight and obesity was 0.85 (95% CI, 0.76–0.96) in education group as compared with control group.ConclusionShort-term health education intervention results in significantly higher reductions in obesity parameters and improvement in awareness in Chinese adolescents