Sintering mechanism of Ag nanoparticle-nanoflake: a molecular dynamics simulation

This paper studied the behaviors of sintering between Ag nanoparticle (NP) and nanoflake (NF) in the same size by molecular dynamics simulation. Before the sintering simulation, the melting simulation of NF was carried out to calculate the melting points of NFs and investigate the thermostability of NF. The Lindemann index and potential energy showed that the melting points of NF were significantly size-dependent. During the heating process, the sharp corner of NF transformed to the round corner and could bend spontaneously lower than melting points. In sintering simulation, the sintering process of NF-NP showed a metastable stage before equilibrium. Under low sintering temperature (500 K), the degree of plasticity sintering mechanism of NF-NP was more prominent, which generated more defects, such as amorphous atoms, dislocations, and stacking faults, than NP-NP. The sintered products of NF-NP also presented a better neck size and shrinkage than NP-NP in the same size. A new sintering behavior was observed: NF was bent toward the NP during the sintering. The bending curvature of NF increased as the thickness or the length/width decreased. For the NF with the ratio of length/width to thickness of 5:1, bending could further significantly facilitate neck growth. At 700 K, the plasticity mechanism dominated both the sintering processes of NF-NP and NP-NP. And NF-NP showed a larger diffusivity than NP-NP. At last, we investigated the effects of crystal misorientation, and found that a tilted grain boundary generated in the neck. The NF had the trend of rotation to decrease the crystal misorientation.Electronic Components, Technology and Material

Parental Smoking and Breastfeeding in Xinjiang, PR China

A cohort of 1088 couples in Xinjiang, PR China, were recruited to study infant feeding practices and paternal smoking. Mothers were interviewed in hospital and at 0.5, 1.5, 2.5, 3.5, 4.5, and 6 months. Survival analysis was used to calculate breastfeeding rates in smokers and nonsmokers. The paternal smoking rate was 64.8% and maternal smoking rate 1.7% (P < .01). The rates for any breastfeeding in the smoking group were significantly lower than in the nonsmoking group from 3.5 months to 6 months (P < .05). The rates for exclusive breastfeeding in the paternal smoking group were lower than in the nonsmoking group from discharge to 6 months (P < .05). The median duration of exclusive breastfeeding in the paternal smoking group was shorter than in the nonsmoking group. Paternal smoking was a risk factor for stopping any breastfeeding (hazard risk, 1.84; 95% confidence interval, 1.11-3.04) and exclusive breastfeeding (hazard risk, 1.33; 95% CI, 1.09-1.64) compared with nonsmokers. J Hum Lact. 26(3):242-247