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Mechanical and thermodynamical properties of bulk polyethylene have been scrutinized using coarse-grained (CG) molecular dynamics simulations. Entangled but cross-link-free polymer clusters are generated by the semicrystalline lattice method for a wide range chain length of alkane modeled by CG beads, and tested under compressive and tensile stress with various temperature and strain rates. It has been found that the specific volume and volumetric thermal expansion coefficient decrease with the increase of chain length, where the specific volume is a linear function of the bond number to all bead number ratios, while the thermal expansion coefficient is a linear rational function of the ratio. Glass-transition temperature, however, does not seem to be sensitive to chain length. Yield stress under tension and compression increases with the increase of the bond number to all bead number ratio and strain rate as well as with decreasing temperature. The correlation found between chain length and these physical parameters suggests that the ratio dominates the mechanical properties of the present CG-modeled linear polymer material. [ABSTRACT FROM AUTHOR]

The chirality-dependent mixed-mode I-II fracture toughness and crack growth angles of singlelayer graphene sheets are determined using molecular dynamics (MD) simulations and the finite element (FE) method based on the boundary layer model, respectively. The carbon-carbon bond in the FE method is equivalent to a nonlinear Timoshenko beam based on the Tersoff-Brenner potential. All the results of the present FE method agree well with those of our MD simulations performed using the REBO potential. The chiral crack angles of α=0° (zigzag), 15°, 30° (or 90°, armchair), and 45° at different loading angles from 0° ≤ φ ≤ 90° (φ = 90° for mode I and φ = 0° for mode II) are studied. The present results show that both critical stress intensity factors (SIFs) and crack growth angles strongly depend on the chiral angle a, the dimensions [in two-dimensional (2D) or three-dimensional (3D) states], as well as the temperature, for a given loading angle u. The critical equivalent SIFs change from 2.52 to 4.07 nN Å-3/2 in the 2D state and from 2.46 to 5.06 nN Å-3/2 in the 3D state at different loading angles. The SIFs are around one order of magnitude smaller than those of ordinary steel, which indicates that chiral graphene is remarkably brittle in contrast to its ultrahigh strength. These findings should be of great help in understanding the chiralitydependent fracture properties of graphene sheets and designing graphene-based nanodevices. [ABSTRACT FROM AUTHOR]

The thermo-mechanical vibration of a single-layer graphene sheet (SLGP) and a single-walled carbon nanotube (SWCNT) on a substrate is studied by using a nonlocal elastic plate model and two nonlocal elastic beam models (including Timoshenko-beam model and Euler-beam model) with quantum effects, respectively. The effect of the van der Waals (vdW) interactions between the SLGP (or the SWCNT) and the substrate on the vibration is obtained. Checking against our molecular dynamics simulations shows that the present models are reasonable. In particular, the radial vibration of the SWCNT on the substrate with quantum effects is further derived through the continuum shell model due to the different vdW forces on each point of the SWCNT circumference. The present models show that the normalized transverse frequency decreases and the normalized radial frequency increases with increasing SWCNT radius, respectively. The radial amplitude of the SWCNT (or the amplitude of the SLGP) nonlinearly increases and the transverse amplitude of the SWCNT linearly increases with increasing temperature for a given distance, respectively. The obtained analytical solution should be of great importance for understanding the thermomechanical vibration of nanoelectronic devices on a substrate. [ABSTRACT FROM AUTHOR]

The peeling behavior of different nanowires or single-walled/multi-walled carbon nanotubes (CNTs) from a substrate is studied by using the Kendall model of the continuum mechanics, where a basic assumption is that the deformation of the part of the nanowire/nanotube attached to the substrate under peeling force is ignored. The cohesive energy between a nanowire (or a CNT) and a substrate is obtained through continuum modeling of the van der Waals interaction, which has high accuracy by comparison of our molecular dynamics simulations. Our analytical results show that the peeling behavior strongly depends on the peeling angle, the pre-tension, the separation distance toward the substrate, the radius, and the Young's modulus of the nanowire (or the CNT). In particular, the peeling forces with a generalized peeling model in the steady-state stage are compared with those of the classical Kendall model. In the generalized peeling model, the effect of the bending stiffness and cohesive energy between the bending nanowire and the substrate on peeling forces is considered. The obtained analytical solution should be of great help for understanding the interaction between the nanostructures and the substrates, and designing nanoelectromechanical systems. [ABSTRACT FROM AUTHOR]

Background: Growing evidence has indicated that some inflammatory markers, including lymphocyte to monocyte ratio (LMR), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and prognostic nutritional index (PNI), can be used as indicators in the prognosis of colorectal cancer (CRC). However, there is controversy concerning what is the best predictor of prognosis in CRC.Methods: A cohort of 1744 CRC patients in our institution was analyzed retrospectively. Harrell's concordance index (c-index) and Bayesian information criterion (BIC) were used to determine the optimal cut-off values of inflammatory markers and compare their predictive capacity. The association of inflammatory markers with overall survival (OS) and cancer-specific survival (CSS) was analyzed using Kaplan-Meier methods with log-rank test, followed by multivariate Cox proportional hazards model.Results: The multivariate analysis indicated that among these inflammatory markers, NLR (< 2.0 vs. ≥ 2.0) was the only independent prognostic factor for poor OS [hazard ratio (HR) = 0.758, 95% confidence intervals (CI) = 0.598-0.960, P = 0.021)] and CSS (HR = 0.738, 95% CI = 0.573-0.950, P = 0.018). Among these inflammatory markers, the c-index and BIC value for NLR were maximum and minimum for OS, respectively. In addition, the c-index was higher and the BIC value was smaller in TNM staging combined with NLR compared with the values obtained in TNM staging alone.Conclusion: NLR is a superior indicator of prognosis compared with LMR, PLR, and PNI in CRC patients, and NLR may serve as an additional indicator based on the current tumor staging system. [ABSTRACT FROM AUTHOR]

Graphene, as a passivation layer, can be used to protect the black phosphorus (BP) from the chemical reaction with surrounding oxygen and water. However, BP and graphene heterostructures have low efficiency of heat dissipation due to its intrinsic high thermal resistance at the interfaces. The accumulated energy from Joule heat has to be removed efficiently to avoid the malfunction of the devices. Therefore, it is of significance to investigate the interfacial thermal dissipation properties and manipulate the properties by interfacial engineering on demand. In this work, the interfacial thermal conductance between few-layer BP and graphene is studied extensively using molecular dynamics simulations. Two important parameters, Pcr, the critical heat power density of maintaining thermal stability, and Pmax, the maximum heat power density with which the system can be loaded, are identified. Our results show that interfacial thermal conductance can be effectively tuned in a wide range by external strains and interfacial defects. The compressive strain can enhance the interfacial thermal conductance by one order of magnitude, while interface defects give a two-fold increase. These findings could provide guidelines in heat dissipation and interfacial engineering for thermal conductance manipulation of BP-graphene heterostructure-based devices. [ABSTRACT FROM AUTHOR]

Demand side management is one of the key topics of smart grids. This study integrates the service computing paradigm in smart grid domain and proposes a demand side personalised recommendation system (PRS). The proposed PRS employs service recommendation techniques to infer residential users' potential interests and needs on energy saving appliances, and then it recommends energy saving appliances to users, therefore potentially creating opportunities to save energy for the grid. The proposed approach starts by applying a non-intrusive appliance load monitoring (NILM) method based on generalised particle filtering to disaggregate the end users' household appliance utilisation profiles from the smart meter data. Based on the NILM results, several inference rules are applied to infer the preferences and energy consumption patterns, and to form the user profile. In parallel, information retrieval techniques are applied to extract keywords from the textual appliance advertisements (Ads), and to define the appliance profile. Finally, the similarity measurement method is applied to compare the user profile and appliance profile, to rank the appliance Ad, and to make the recommendations. Experiments are conducted to validate the proposed system. [ABSTRACT FROM AUTHOR]