We propose parametrizing the Stillinger-Weber potential for covalent materials starting from the valence force-field model. All geometrical parameters in the Stillinger-Weber potential are determined ...analytically according to the equilibrium condition for each individual potential term, while the energy parameters are derived from the valence force-field model. This parametrization approach transfers the accuracy of the valence force field model to the Stillinger-Weber potential. Furthermore, the resulting Stilliinger-Weber potential supports stable molecular dynamics simulations, as each potential term is at an energy-minimum state separately at the equilibrium configuration. We employ this procedure to parametrize Stillinger-Weber potentials for single-layer MoS2 and black phosphorous. The obtained Stillinger-Weber potentials predict an accurate phonon spectrum and mechanical behaviors. We also provide input scripts of these Stillinger-Weber potentials used by publicly available simulation packages including GULP and LAMMPS.
Abstract
We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state (EOS) of neutron stars employing either variable- or ...constant-likelihood functions. The former has the advantage of retaining the full information on the distributions of the measurements, making exhaustive usage of the data. The latter, on the other hand, has the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound speed parameterization method so as to satisfy the constraints from X-ray and gravitational waves observations, as well as those from chiral effective theory and perturbative quantum chromodynamics. In all cases, the two approaches lead to very similar results and the 90% confidence levels essentially overlap. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff on the binary tidal deformability
Λ
˜
≤
720
set in the constant-likelihood approach. Our analysis has also produced two additional results. First, an inverse correlation between the normalized central number density,
n
c
,TOV
/
n
s
, and the radius of a maximally massive star,
R
TOV
. Second, and most importantly, it has confirmed the relation between the chirp mass and the binary tidal deformability. The importance of this result is that it relates
chirp
, which is measured very accurately, and
Λ
˜
, which contains important information on the EOS. Hence, when
chirp
is measured in future detections, our relation can be used to set tight constraints on
Λ
˜
.
Abstract
Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat ...dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.
The Poisson's ratio is a fundamental mechanical property that relates the resulting lateral strain to applied axial strain. Although this value can theoretically be negative, it is positive for ...nearly all materials, though negative values have been observed in so-called auxetic structures. However, nearly all auxetic materials are bulk materials whose microstructure has been specifically engineered to generate a negative Poisson's ratio. Here we report using first-principles calculations the existence of a negative Poisson's ratio in a single-layer, two-dimensional material, black phosphorus. In contrast to engineered bulk auxetics, this behaviour is intrinsic for single-layer black phosphorus, and originates from its puckered structure, where the pucker can be regarded as a re-entrant structure that is comprised of two coupled orthogonal hinges. As a result of this atomic structure, a negative Poisson's ratio is observed in the out-of-plane direction under uniaxial deformation in the direction parallel to the pucker.
Structurally precision graphene nanoribbons (GNRs) have attracted great interest considering their prospective applications as organic carbon materials for nanoelectronics. The electronic properties ...of GNRs not only critically depend on the edge structure and width but also on the heteroatom type, doping position, and concentration. Motivated by the recent undisputable progress in the synthesis of stable boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs), considerable efforts have been devoted to the precision synthesis of the corresponding boron‐doped GNRs (B‐GNRs) via bottom‐up synthesis approach in recent years in view of the extraordinary ability of boron doping on modulating their physiochemical properties. In this review, an overview of the bottom‐up organic synthesis of B‐GNRs, including the precursor design and synthesis, structure characterization of the resulting B‐GNRs, and investigation of their electronic properties is provided. Moreover, the future challenges and perspectives regarding the bottom‐up synthesis of B‐GNRs are also discussed. The authors hope that this review will further stimulate the synthesis and device integrations of B‐GNRs with a combined effort from different disciplines.
In this review, recent progress in the bottom‐up organic synthesis and characterization of boron‐doped graphene nanoribbons through on‐surface or in‐solution chemistry is presented. Moreover, the challenges and perspectives in this research field are also discussed.
Graphene and MoS2 are two well-known quasi two-dimensional materials. This review presents a comparative survey of the complementary lattice dynamical and mechanical properties of graphene and MoSs, ...which facilitates the study of graphene/MoS2 heterostructures. These hybrid heterostructures are expected to mitigate the negative properties of each individual constituent and have attracted intense academic and industrial research interest.
Electric vehicle (EV) dynamical wireless charging is an emerging application area of wireless power transfer technologies. Compared with a classical static charging mode, there are two key challenges ...in a dynamical charging process. One is to determine charging area and corresponding excitation unit. The other is to provide large energy in a short time interval. Based on multiexcitation unit configuration for EV dynamical charging, this paper proposes a charging area determining method. The dynamical mutual inductance can be calculated based on dc current input and load detection. A charging area can be figured out based on output power requirement. And a switching mode method is given to control the charging process for multiexcitation unit configuration. On this basis, a power and efficiency enhancement method is proposed by utilizing a multiexcitation unit in the charging area. This method is beneficial for improving system power capacity without increasing the voltage and current stress. Finally, experimental results show that this method can realize accurate charging area determining and control. And the output power of dual excitation unit configuration can increase almost four times than that of a traditional single excitation unit configuration.
Oridonin, an active diterpenoid isolated from Rabdosia rubescens, has been reported for its antitumor activity on several cancers. However, its effect on human esophageal cancer remains unclear. In ...this study, we demonstrated that oridonin could inhibit the growth of human esophageal cancer cells both in vitro and in vivo. Oridonin not only suppressed the proliferation, but also induced cell cycle arrest and mitochondrial‐mediated apoptosis in KYSE‐30, KYSE‐150, and EC9706 cells with dose‐dependent manner. Further mechanism studies revealed that oridonin led cell cycle arrest in esophageal cancer cells via downregulating cell cycle‐related proteins, such as cyclin B1 and CDK2, while upregulating p53 and p21. Oridonin also increased proapoptotic protein Bax and reduced antiapoptotic protein Bcl‐2, as well as the increased expression of cleaved caspase‐3, ‐8, and ‐9. In addition, oridonin treatment could significantly inhibit the PI3K/Akt/mTOR and Ras/Raf signaling pathway. In vivo results further demonstrated that oridonin treatment markedly inhibited tumor growth in the esophageal cancer xenograft mice model. Taken together, these results suggest that oridonin may be a potential anticancer agent for the treatment of esophageal cancer.
Oridonin exerted its anticancer capacity via inhibition of PI3K/AKT/mTOR and Ras/Raf signaling pathway. Oridonin suppressed esophageal tumor growth in vivo by inhibiting antiangiogenesis and inducing cancer cell apoptosis.
In this paper, a reactive power sharing strategy that employs communication and the virtual impedance concept is proposed to enhance the accuracy of reactive power sharing in an islanded microgrid. ...Communication is utilized to facilitate the tuning of adaptive virtual impedances in order to compensate for the mismatch in voltage drops across feeders. Once the virtual impedances are tuned for a given load operating point, the strategy will result in accurate reactive power sharing even if communication is disrupted. If the load changes while communication is unavailable, the sharing accuracy is reduced, but the proposed strategy will still outperform the conventional droop control method. In addition, the reactive power sharing accuracy based on the proposed strategy is immune to the time delay in the communication channel. The sensitivity of the tuned controller parameters to changes in the system operating point is also explored. The control strategy is straightforward to implement and does not require knowledge of the feeder impedances. The feasibility and effectiveness of the proposed strategy are validated using simulation and experimental results from a 2-kVA microgrid.
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