Preparation of Nickel-Based Nanolubricants and Investigation of their Tribological Behavior

In situ surface-modification technique is adopted in present research to fabricate a series of Ni nanoparticles as well as Cu@Ni nanoparticles with different size and morphology. The correlation among the composition, structure, size, and morphology and tribological properties of as-synthesized additives were explored, and the friction-reducing, antiwear, and worn surface self-healing mechanisms of the additives were discussed. It was found that Ni nanoparticles with a smaller size show higher surface activity and can readily deposit on the sliding surface and form a stable and continuous protective layer thereon. Compared with sphere-like and triangular rod-like Ni nanoparticles, triangular plate-like Ni nanoparticles are more liable to form protective layer. Compared to Ni-based nanolubricants, as-synthesized Cu@Ni nanolubricants exhibit better friction-reducing, antiwear, and extreme pressure properties. It is because the highly active Ni nanocores and O- and N-containing organic modifying agents can readily form boundary lubricating film on sliding steel surfaces, while Cu nanocores can easily deposit on sliding steel surface to form a protective layer (self-healing film) thereon. Ni nanoparticles as nanoadditives in solid-liquid lubricating system significantly reduce the friction in all lubrication regimes: As a nanolubricant, Ni nanoparticles exhibit popular and effective friction-reducing, antiwear, and extreme pressure properties

Nonlinear Instability for a Leslie-Gower Predator-Prey Model with Cross Diffusion

A rigorous mathematical characterization for early-stage spatial and temporal patterns formation in a Leslie-Gower predator-prey model with cross diffusion is investigated. Given any general perturbation near an unstable constant equilibrium, we prove that its nonlinear evolution is dominated by the corresponding linear dynamics along a fixed finite number of the fastest growing modes

Synthesis and Application of Copper Nanowires and Silver Nanosheet-Coated Copper Nanowires as Nanofillers in Several Polymers

A large amount of copper (Cu) nanowires was synthesized through the reduction of Cu(OH)2 by hydrazine in an aqueous solution containing NaOH and ethylenediamine. Besides, Cu nanowires coated by silver nanosheet (denoted as Cu@Ag nanowires) were prepared with a facile transmetalation reaction method. In the meantime, the as‐prepared Cu and Cu@Ag nanowires were used as the nanofillers of polyvinyl chloride (PVC), ultra‐high molecular weight polyethylene (UHMWPE) and epoxy resin (EP), and their effects on the thermal properties and mechanical properties as well as friction and wear behavior of the polymer‐matrix composites nanocomposites were examined. Results indicate that the as‐prepared Cu@Ag nanowires consist of Cu nanowires core and Ag nanosheet shell. The Ag nanosheet shell can well inhibit the oxidation of the Cu nanowires core, thereby providing the as‐prepared Cu@Ag nanowires with good thermal stability even at an elevated temperature of 230°C. As compared with Cu nanowires, Cu@Ag nanowires could effectively increase the thermal stability of the PVC matrix composites. Moreover, due to the special morphology and microstructure, the as‐prepared Cu@Ag nanowires can effectively improve the mechanical properties and wear resistance of PVC, UHMWPE, and EP

Bigeye tuna fishing ground in relation to thermocline in the Western and Central Pacific Ocean using Argo data

444-451The relationship beween thermocline and bigeye tuna (Thunnus obesus) fishing grounds in the Western and Central Pacific Ocean was evaluated by Argo data and monthly CPUE (catch per unit effort). The generalized additive model indicated evidence of nonlinear relationships between CPUE and six thermocline characteristics. The results suggested that the fishing grounds distributed where the upper boundary temperature was about 26 ºC and the upper boundary depth values between 70 and 100 m. The fishing grounds located between the two high value shapes of the lower boundary depth of thermocline, if the depth was >300 or <150 m, the CPUE tended to be low. The lower boundary temperature of the thermocline in the fishing grounds was lower than 13 ºC. Conversely, if the temperature was higher than 17 ºC, the hooking rates were very low. The strongest relationship between CPUE with thermocline thickness and thermocline strength was approximately at 60 m and 0.1 ºC/m. The optimum ranges for the upper boundary thermocline temperature and depth and the lower boundary thermocline temperature and depth, thermocline thickness and thermocline strength were between 26-29 ºC, 70-110 m, 11-13 ºC, 200-280 m, and 0.01-0.15 ºC/m, 60-80 m, respectively

Multiscale Modeling of Skeletal Muscle Active Contraction in Relation to Mechanochemical Coupling of Molecular Motors

In this work, a mathematical model was developed to relate the mechanochemical characterizations of molecular motors with the macroscopic manifestation of muscle contraction. Non-equilibrium statistical mechanics were used to study the collective behavior of myosin molecular motors in terms of the complex conformation change and multiple chemical states in one working cycle. The stochastic evolution of molecular motor probability density distribution during the contraction of sarcomere was characterized by the Fokker-Planck Equation. Quick muscle contraction was demonstrated by the collective dynamic behavior of myosin motors, the muscle contraction force, and the muscle contraction velocity-force relation. Our results are validated against published experiments, as well as the predictions from the Hill’s model. The quantitative relation between myosin molecular motors and muscle contraction provides a novel way to unravel the mechanism of force generation

Influence of sea ice and sea surface temperature on the abundance of Antarctic krill in Area 48.2

In this paper we examine the relationship between Antarctic krill catch, sea ice concentration, and sea surface temperature (SST). Data on the Antarctic krill catch from 2003 to 2010 in CCAMLR Area 48.2 were combined with sea ice and SST data. Results showed that krill fishing in Area 48.2 took place from February to August each year but the catch was concentrated from March to July, with production during this period accounting for about 99.3% of the annual catch. Regression analysis showed that the catch per unit effort (CPUE) was clearly related to sea ice concentration and SST intervals. CPUE was negatively correlated with the area of sea ice among years (R2=0.64), and the correlation was strongest (R2=0.71) when sea ice concentration was greater than 90%. Over the months the CPUE initially increased, then decreased as the area of sea ice increased. The relationship was strongest (R2=0.88) when the concentration of sea ice was 60%—70%. There was no negative correlation among years between CPUE and the ice-free area when SST was between -2℃and 3℃ (R2=0.21), but there was a significant negative correlation when SST was between 1℃ and 2℃ (R2=0.82). Over the months, CPUE initially increased then decreased with increasing sea ice-free area, and the relationship was strongest (R2=0.94) when SST was between 0℃ and 1℃. This study shows that sea ice concentration and SST have significant effects on the abundance of krill in Area 48.2, and the findings have practical significance for the use and conservation of Antarctic krill resources

Evaluation of the effects of forest management strategies on carbon sequestration in evergreen broad-leaved (Phoebe bournei) plantation forests using FORECAST ecosystem model

In the context of global climate change, it is critical to study how different forest management practices affect forest carbon sequestration. This is especially important for forest managers and policy makers who will have to design and implement appropriate mitigation and adaptation strategies. Previous research has focused on coniferous plantations with rare examination of plantations of evergreen broadleaved species. Phoebe bournei (Hemsley) Yang, as one of the representative species of subtropical evergreen broadleaf forests in Asia, has a unique potential to increase forest carbon sink. In this study, field data were combined with the forest ecosystem management model FORECAST to estimate the impacts of different forest management strategies (combinations of planting densities from 1000 to 4000 trees ha-1, rotation lengths from 20 to 80 years, and different harvesting intensities: stem-only, whole-tree and complete-tree) on carbon sequestration of Phoebe bournei plantations in south-eastern China. Field and previously published data were used to calibrate the model for stand biomass pools accumulation, stand density and mortality, light response curves, photosynthetic efficiency, and data on soil nutrient pools, for three different site conditions. The results showed that the most suitable planting density to maximize carbon sequestration in Phoebe bournei plantations is 2000-3000 trees ha-1. Long rotations (80 years) are better than shorter rotations (20 or 30 years) for the long-term maintenance of site productivity, though the recommended rotation length for maximizing carbon sequestration and maintaining forest productivity is 40-60 years. As for harvesting intensity, stem-only harvesting is the most suitable strategy to manage for carbon sequestration when maintaining long-term site productivity, with whole-tree and complete-tree harvesting constituting less optimal options. Our modelling exercise indicates that Phoebe bournei plantations have great potential for carbon sequestration if they are managed under sustainable and ecologically-based strategies. Given that forests are important in the global carbon cycle, it is recommended that afforestation efforts in relevant sub-tropical regions use appropriate broad-leaved species that can help resolve ecological and socio-economic challenge

The feasibility study of non-invasive fetal trisomy 18 and 21 detection with semiconductor sequencing platform

Objective: Recent non-invasive prenatal testing (NIPT) technologies are based on next-generation sequencing (NGS). NGS allows rapid and effective clinical diagnoses to be determined with two common sequencing systems: Illumina and Ion Torrent platforms. The majority of NIPT technology is associated with Illumina platform. We investigated whether fetal trisomy 18 and 21 were sensitively and specifically detectable by semiconductor sequencer: Ion Proton. Methods: From March 2012 to October 2013, we enrolled 155 pregnant women with fetuses who were diagnosed as high risk of fetal defects at Xiamen Maternal &amp; Child Health Care Hospital (Xiamen, Fujian, China). Adapter-ligated DNA libraries were analyzed by the Ion Proton??? System (Life Technologies, Grand Island, NY, USA) with an average 0.3 ?? sequencing coverage per nucleotide. Average total raw reads per sample was 6.5 million and mean rate of uniquely mapped reads was 59.0%. The results of this study were derived from BWA mapping. Z-score was used for fetal trisomy 18 and 21 detection. Results: Interactive dot diagrams showed the minimal z-score values to discriminate negative versus positive cases of fetal trisomy 18 and 21. For fetal trisomy 18, the minimal z-score value of 2.459 showed 100% positive predictive and negative predictive values. The minimal z-score of 2.566 was used to classify negative versus positive cases of fetal trisomy 21. Conclusion: These results provide the evidence that fetal trisomy 18 and 21 detection can be performed with semiconductor sequencer. Our data also suggest that a prospective study should be performed with a larger cohort of clinically diverse obstetrics patients.open2