Towards a unified nonlocal, peridynamics framework for the coarse-graining of molecular dynamics data with fractures

Molecular dynamics(MD)has served as a powerful tool for designing materials with reduced reliance on laboratory testing.However,the use of MD directly to treat the deformation and failure of materials at the mesoscale is still largely beyond reach.In this work,we propose a learning framework to extract a peridynamics model as a mesoscale continuum surrogate from MD simulated material fracture data sets.Firstly,we develop a novel coarse-graining method,to automatically handle the material fracture and its corresponding discontinuities in the MD displacement data sets.Inspired by the weighted essentially non-oscillatory(WENO)scheme,the key idea lies at an adaptive procedure to automatically choose the locally smoothest stencil,then reconstruct the coarse-grained material displacement field as the piecewise smooth solutions containing discontinuities.Then,based on the coarse-grained MD data,a two-phase optimizationbased learning approach is proposed to infer the optimal peridynamics model with damage criterion.In the first phase,we identify the optimal nonlocal kernel function from the data sets without material damage to capture the material stiffness properties.Then,in the second phase,the material damage criterion is learnt as a smoothed step function from the data with fractures.As a result,a peridynamics surrogate is obtained.As a continuum model,our peridynamics surrogate model can be employed in further prediction tasks with different grid resolutions from training,and hence allows for substantial reductions in computational cost compared with MD.We illustrate the efficacy of the proposed approach with several numerical tests for the dynamic crack propagation problem in a single-layer graphene.Our tests show that the proposed data-driven model is robust and generalizable,in the sense that it is capable of modeling the initialization and growth of fractures under discretization and loading settings that are different from the ones used during training.

Effects of Cryoprotective Agents on the Bovine Articular Chondrocyte Viability

Cryopreservation is the process of choice for long term preservation of cells and tissues. In this study, the effects of cryoprotective agents, dimethyl sulfoxide(DMSO), glycerol and 1,2 propanediol on the bovine articular chondrocyte viability were examined experimentally. The CPA was added at the concentrations of 0 6, 0 9, 1 2 and 1 5 mol/L and at 4 ℃ and 37 ℃ and removed at 37 ℃ in one step. CPA stepwise addition and removal at 0 6 and 1 2 mol/L and at 37 ℃ was also tested as an alternative protocol. Cell volume excursion during DMSO addition and removal was estimated and correlated well with cell survival rates. Solution makeup affects cell survival rate and a stepwise protocol can improve the cell survival rates significantly.

Subpulse Drifting of PSR J1110–5637

We report a detailed study of polarization characteristics and subpulse drifting in PSR J1110-5637 with the observations of the Parkes 64 m radio telescope at 1369 MHz.The observations revealed that the trailing component of the pulse profile has obvious subpulse drifting,while the leading component has no subpulse drifting.Using the two-dimensional fluctuation spectrum(2DFS),we detected three distinct emission modes in the trailing component(modes A,B and C).The emission in mode A is chaotic and indistinguishable,while modes B and C have obvious subpulse drifting.The vertical modulation periods P3of modes B and C are around the mean values of 12 P and 8 P,respectively.The subpulse drifting of PSR J1110-5637 will expand the pulsar sample with multiple subpulse drifting rates,and this will help future systematic studies on the physical origin of the subpulse drifting phenomenon.

Ground-state mass of ^(22)Al and test of state-of-the-art ab initio calculations

The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou.The new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 keV.When compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)keV.The excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory.The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.

Chromodynamic Lattice Boltzmann Method for the Simulation of Drops,Erythrocytes,and other Vesicles

Recently,we have validated a three-dimensional,single framework multicomponent lattice Boltzmann method,modified to generate vesicles(rather than drops)[“Three-dimensional single framework multicomponent lattice Boltzmann equation method for vesicle hydrodynamics,”Phys.Fluids 33,077110(2021)].This approach implements an immersed boundary force distribution,characterised by bending rigidity,surface tension,preferred curvature and conserved membrane area,in which work we successfully validated isolated vesicle flows against other methodologies and experiment.Like most immersed boundary algorithms,our method relies on numerical computation of high-order spatial derivatives and an intricate body force density.The next step is to verify that it has sufficient numerical stability to address the anticipated application of high volume fraction flows of highly deformable objects in intimate interaction.It is this in silico verification-of both the class of fluid object attainable and the stability of the later in strong,straining and shearing flows which is at issue,here.We extend our method to simulate multiple variously deflated vesicles and multiple liquid droplets still within a single framework,from which our fluid objects emerge as particular parameterisations.We present data from simulations containing up to four vesicles(five immiscible fluid species),which threshold verifies that simulations containing unlimited fluid objects are possible[“Modeling the flow of dense suspensions of deformable particles in three dimensions,”Phys.Rev.E 75,066707(2007)].These data also assure the ability of our immersed boundary forcing to preserve the character and integrity of fluid objects in interactions characterised by large local velocity gradients(intimate squeezing,shearing and elongational straining).Throughout,we take interfacial or membrane area,A,as a proxy for stability and physical veracity.

The AME2012 atomic mass evaluation(Ⅰ).Evaluation of input data,adjustment procedures

This paper is the second part of the new evaluation of atomic masses, AME2012. From the results of a leastsquares calculation, described in Part I, for all accepted experimental data, we derive here tables and graphs to replace those of AME2003. The first table lists atomic masses. It is followed by a table of the influences of data on primary nuclides, a table of separation energies and reaction energies, and finally, a series of graphs of separation and decay energies. The last section in this paper lists all references to the input data used in Part I of this AME2012 and also to the data included in the NUBASE2012 evaluation （first paper in this issue）.

The AME2012 atomic mass evaluation(Ⅱ).Tables,graphs and references

This paper is the first of two articles （Part I and Part II） that presents the results of the new atomic mass evaluation, AME2012. It includes complete information on the experimental input data （including not used and rejected ones）, as well as details on the evaluation procedures used to derive the tables with recommended values given in the second part. This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction, decay and mass-spectrometer results. These input values were entered in the least-squares adjustment procedure for determining the best values for the atomic masses and their uncertainties. Calculation procedures and particularities of the AME are then described. All accepted and rejected data, including outweighed ones, are presented in a tabular format and compared with the adjusted values （obtained using the adjustment procedure）. Differences with the previous AME2003 evaluation are also discussed and specific information is presented for several cases that may be of interest to various AME users. The second AME2012 article, the last one in this issue, gives a table with recommended values of atomic masses, as well as tables and graphs of derived quantifies, along with the list of references used in both this AME2012 evaluation and the NUBASE2012 one （the first paper in this issue）.

Recent development in the application of bulk metallic glasses

Over the past decades,considerable efforts have been made in the commercial application of bulk metallic glasses(BMGs).Despite great challenges faced by the industrial players,significant progress has been achieved,and millions of commercial products for various kinds of applications have been shipped around the world.Here in this paper,we shall present the alloys suitable for the actual products in the application and discuss the merits of the processing technique of BMGs over the existing processing techniques and materials.Most importantly we demonstrate the typical examples of products over the past few years.Finally,future directions of the industrialization of BMGs are also discussed.

A high specific Young's modulus steel reinforced by spheroidal kappa-carbide

1.Introduction High strength steels continue to be developed for automotive applications to increase safety and reduce lightweight by downgauging[1,2].In addition,reducing density is another solution for the lightweight of automotive components[3,4].Aluminum addition could effectively reduce the density of steels,since it has a low atomic mass and invokes a lattice expansion[5].

3D-Stacked Multistage Inertial Microfluidic Chip for High-Throughput Enrichment of Circulating Tumor Cells

Whether for cancer diagnosis or single-cell analysis,it remains a major dhallenge to isolate the target sample cells from a large background cell for high-efficiency downstream detection and analysis in an integrated chip.Therefore,in this paper,we propose a 3D stacked multistage inertial microfluidic sorting chip for high-throughput enrichment of circulating tumor cells(CTCs)and convenient downstream analysis.In this chip,the first stage is a spiral channel with a trapezoidal cross-section,which has better separation performance than a spiral channel with a rectangular cross-section.The second and third stages adopt symmetrical square serpentine channels with different rectangular cross-section widths for further separation and enrichment of sample cells reducing the outlet flow rate for easier downstream detection and analysis.The multistage channel can separate 5 pum and 15 um particles with a separation efficiency of 92.37%and purity of 98.10%at a high inlet flow rate of 1.3 mL/min.Meanwhile,it can separate tumor cells(SW480,A549,and Caki-1)from massive red blood cells(RBCs)with a.separation efficiency of>80%,separation purity of>90%,and a concentration fold of~20.The proposed work is aimed at providing a high-throughput sample processing system that can be easily integrated with flowing sample detection methods for rapid CTC analysis.