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We study the Cauchy problem of the new model of the three dimensional inertial nematic electrolyte, which models the N-species charged particles diffuse and advect in the nematic liquid crystalline matrix. This new model was proposed by [Calderer MC, Golovaty D, Lavrentovich O, et al. Modeling of nematic electrolytes and nonlinear electroosmosis. SIAM J Appl Math. 2016;76:2260–2285. doi: 10.1137/16M1056225]. The inertial effect is such that the system involves a hyperbolic feature. We first derive the local existence in large initial data when the flow is isotropy, i.e. $ \lambda =1 $ λ = 1. For the anisotropy case ( $ \lambda \gt 0 $ λ > 0 , $ \lambda \neq ~1 $ λ ≠ 1), we obtain small data local solutions. Then, by seeking some further dissipative mechanisms from the elliptic structures, the local solution can be extended globally near the constant states with electro-neutrality condition. [ABSTRACT FROM AUTHOR]

We study the effects of additive and multiplicative noise on the solution landscape of nematic liquid crystals confined to a square domain within the Landau-de Gennes framework, as well as the impact of additive noise on the symmetric radial hedgehog solution for nematic droplets. The introduction of random noise can be used to capture material uncertainties and imperfections, which are always present in physical systems. We implement random noise in our framework by introducing a $Q$ Q -Wiener stochastic process to the governing differential equations. On the square, the solution landscape for the deterministic problem is well understood, enabling us to compare and contrast the deterministic predictions and the stochastic predictions, while we demonstrate that the symmetry of the radial hedgehog solution can be violated by noise. This approach of introducing noise to deterministic equations can be used to test the robustness and validity of predictions from deterministic liquid crystal models, which essentially capture idealised situations. [ABSTRACT FROM AUTHOR]

In this work, wire arc additive manufactured IN718 materials with different textures and defect characteristics were obtained via two deposition strategies: parallel mode (P_mode) and oscillation mode (O_mode). The influences of these microstructure variables on the low-cycle fatigue (LCF) properties were systematically investigated by experimental and crystal plasticity finite element (CPFE) frameworks. Results revealed that the weak texture of the O_mode sample may be detrimental to LCF due to strain incompatibility between adjacent grains. However, large-sized pore defects in the P_mode samples significantly increased the dispersity of LCF life. The sensitivity of fatigue crack initiation to critical defect size and location was further accurately captured based on the stored energy density criterion, and the fatigue crack nucleation life was also quantified. Finally, the LCF limit was calculated based on the Coffin-Manson equation, and the life prediction intervals of WAAMed-IN718 alloys with different deposition strategies were unified. [ABSTRACT FROM AUTHOR]

Microstructural defects in laser powder bed fusion (LPBF) metallic materials are correlated with processing parameters. A multi-physics model and a crystal plasticity framework are employed to predict microstructure growth in molten pools and assess the impact of manufacturing defects on plastic damage parameters. Criteria for optimising the LPBF process are identified, addressing microstructural defects and tensile properties of LPBF Hastelloy X at various volumetric energy densities (VED). The results show that higher VED levels foster a specific Goss texture {110} <001>, with irregular lack of fusion defects significantly affecting plastic damage, especially near the material surface. A critical threshold emerges between manufacturing defects and grain sizes in plastic strain accumulation. The optimal processing window for superior Hastelloy X mechanical properties ranges from 43 to 53 J/mm3. This work accelerates the development of superior strengthductility alloys via LPBF, streamlining the trial-and-error process and reducing associated costs. [ABSTRACT FROM AUTHOR]

We demonstrate a dislocation density-based crystal plasticity (CP) model approach for simulating mesoscale deformation and damage. The existing CP framework is extended to be compatible with the oxygen-free phosphorous copper microstructure that is the focus of this study. The key aim is to introduce relevant plastic deformation mechanisms and to develop a failure model capable of depicting creep damage in the material. The effect of local variations in material is evaluated, and the model response is compared with experiments and characterisation. The basis of this work is CP material modelling, including grain orientation and size, obtained using electron backscatter diffraction and experimental test data of real relaxation test specimens. This will yield a realistic description of texture and grain shape and, ultimately, accurate stress–strain response at the microstructural level for further evaluation of performance with respect to material creep(−fatigue) damage. [ABSTRACT FROM AUTHOR]

We consider a stochastic 2D liquid crystal model with a multiplicative noise of Lévy type, which models the dynamic of nematic liquid crystals under the influence of stochastic external forces of jump type. We derive a large deviation principle for the model. The proof is based on the weak convergence method introduced in [Budhiraja A, Dupuis P, Maroulas V. Variational representations for continuous time processes. Ann Inst Henri Poincar Probab Stat. 2011;47(3):725–747]. [ABSTRACT FROM AUTHOR]

We shall investigate the existence, uniqueness and regularity of global solutions to a Cauchy problem for a square phase crystal field model with applications to crystal dynamics. To prove the existence of weak solutions we employ the energy method, and to investigate the regularity of solutions we make use of various techniques to derive delicate a priori estimates. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomer-based actuators (LCEAs) exhibit large, reversible deformation, which demonstrates superior advantages in developing remote controlled, light-weighted soft robots. However, deformation of LCEAs undergoes complicated physical dynamics and exhibits highly nonlinear hysteretic characteristics, posing challenges in the realization of related applications. It is necessary to develop a dynamic model that captures the characteristics of LCEAs. With this purpose, this paper proposes a dynamic modelling approach for LCEAs to provide a hybrid model for LCEAs with reduced computational complexity and high precision. In the research, a modelling scheme based on a physics-phenomenon-combined approach for LCEAs is proposed, which considers the elastic free energy, the nematic free energy and dissipation of the LCEA. Physics-based models are then developed to describe these energies. Meanwhile, a phenomenon-based model is proposed to characterise the hysteresis as a component of the nematic free energy. The above models are combined together to provide the final hybrid model for the LCEA. To verify the proposed model, a photo-responsive LCEA experimental platform is established and experiments are conducted. Model parameters are identified based on the nonlinear least-squares method. The experimental results demonstrate the proposed model as an excellent representative to characterise LCEAs' dynamic behaviours. [ABSTRACT FROM AUTHOR]

In this paper, an accurate numerical modelling of nematic liquid crystal for the inverted microstrip phase shifter is presented. Four kinds of liquid crystal with different values of anisotropy have been studied using the conventional simplified liquid crystal model where the liquid crystal is usually assumed isotropic and homogeneous. The S parameters of the phase shifter based on these liquid crystals are simulated. Moreover, considering the anisotropy and inhomogeneous of liquid crystal, the accurate modelling of nematic liquid crystal BL006 applied in the phase shifter under the voltage is calculated. The distribution of the director and permittivity of liquid crystal at the steady state under different voltages is obtained. Based on the accurate modelling results of liquid crystal BL006, the phase shifter is remodelled and simulated. Compared with that of the simplified model, the maximum differential phase shift of the phase shifter based on the liquid crystal BL006 in the accurate model at the centre frequency of 20 GHz was reduced by about 36:5°, and this error will increase with the increasing of the frequency. This numerical modelling method of liquid crystal also can be used in the design of other microwave devices based on nematic liquid crystal. [ABSTRACT FROM AUTHOR]

Liquid viscosity measurement, especially the accurate detection of high-viscosity liquid, has been a hot research in biomedical, petrochemical, and other industries. In this article, a series resonant resistance response of quartz crystal microbalance (QCM) under the droplet model is introduced to characterize the density and viscosity of the liquid. The experimental results of water, glycerol solution with 50% water content, and pure glycerol show that the resonant resistance has a similar response to the resonant frequency and higher stability. Compared with the traditional method in which QCM contacts liquid on one side, this new method has the advantages of extremely high-quality factor, wide measurement range, and minimal reagent requirement, which has important guiding significance for the application of QCM in high-viscosity liquids. [ABSTRACT FROM AUTHOR]

This article models experimentally observed three-dimensional particle-like waves that develop in nematic liquid crystals, with negative dielectric and conductive anisotropy, when subject to an applied alternating electric field. The liquid crystal is confined in a thin region between two plates, perpendicular to the applied field. The horizontal, uniformly aligned director field is at equilibrium due to the negative anisotropy of the media. However, such a state is unstable to perturbations that manifest themselves as confined, bullet-like, director distortions travelling up and down the sample at a speed of several hundred microns per second. It is experimentally predicted that flexoelectricity plays a key role in generating the soliton-like behaviour. We develop a variational model that accounts for ansiostropic dielectric, conductive, flexolectric, elastic and viscous forces. We perform a stability analysis of the uniformly aligned equilibrium state to determine the threshold wave numbers, size, phase-shift and speed of the soliton-like disturbance. We show that the model predictions are in very good agreement with the experimentally measured values. The work models and analyzes a three-dimensional soliton-like instability reported, for the first time in flexoelectric liquid crystals, pointing towards a potential application as a new type of nanotransport device. [ABSTRACT FROM AUTHOR]

The modified phase field crystal model is a sixth order nonlinear generalized damped wave equation. Two linearized difference schemes are presented based on the method of order reduction. One scheme is second order both in time and space, and the other scheme is convergent with the second temporal order and fourth spatial order. A theoretical analysis is carried out by the energy argument and mathematical induction. The uniqueness of the numerical solution and unconditional convergence in discrete L ∞ -norm are proved rigorously. Numerical results demonstrate that the presented schemes for the modified phase field crystal equation can achieve the theoretical convergence order. [ABSTRACT FROM AUTHOR]

The micromechanism-based stepwise strain hardening behaviour of copper single crystals significantly depends on the competition and collaboration between dislocation slip and deformation twinning. A crystal plasticity-based model of the strain hardening characteristics associated with slip and twinning interactions is proposed that focuses on modelling the stepwise strain hardening behaviour. An accumulated twin volume fraction is incorporated into the evolution of slip resistance to model slip–twinning (S-T) interactions at small strains. Then, the following stress fluctuation stage caused by the crystal reorientation is related to the twinning–twinning (T-T) interactions. Upon deformation to a large strain, a saturated hardening law including the slip–slip (S-S) interactions in the twinned region and the accumulated slip are presented. The effects of the initial crystal orientation and twinning on distinguished hardening stages are investigated. The stepwise strain hardening model reveals the dominating hardening mechanism at the initial hardening stage, which has been identified for orientation-dependent copper single crystals by investigating the slip and twinning increments. The stress fluctuation of a copper single crystal with a particular grain orientation can be described by introducing the evolution of the twin volume fraction and its saturation value, which allows an in-depth understanding of the evolution of large plastic deformation. [ABSTRACT FROM AUTHOR]

Micro/nano-structural polyaniline materials were prepared by using thin glass tubes as template in the presence of β2-SiW11Mn and ammonium persulfate, which were used as dopant and oxidant, respectively, in this system. The materials were characterized by IR, UV-Vis, XRD, TG-DTA and SEM techniques. The photocatalytic performance of polyaniline, β2-SiW11Mn and β2-SiW11Mn/PANI composite obtained was investigated using photodegradation of crystal violet as model reaction. The results showed that the photocatalytic activity of β2-SiW11Mn/PANI composite was much higher than polyaniline and β2-SiW11Mn due to a synergy between the two. The degradation rate of crystal violet was 91.19%. [ABSTRACT FROM AUTHOR]

The characterization of polyoxometalates (POMs) structures in solutions is challenging although X-ray diffraction is widely used to solve the POMs' crystalline structures. Here, we introduce small-angle X-ray scattering (SAXS) to explore the solutions of several emergent POMs mainly from Prof. Enbo Wang's group. Direct evidence of their crystal structure retained in solution is obtained by fitting their SAXS data with appropriate crystal structure models, ensuring credibility of their applications for catalysis and magnetism. The capability of distinguishing dimer and monomer structures of {Ce20W100} in solution is of special interest, which is difficult for other characterization techniques. [ABSTRACT FROM AUTHOR]

Continuum crystal plasticity models based on the kinematics of plastic slip are widely developed and used in recent years to describe the anisotropic elasto-viscoplastic behaviour of metallic material. Various microstructural physical-based models have been proposed to reproduce experimental evolutions. This work aims to analyse and compare different crystal plasticity finite element models, especially those based on dislocation densities, from the simulations of stress–strain curves of a nickel base super alloy CMSX-4. Special attention is paid on hardening matrix. The adequacy between the simulated results and experimental data is commented, and it is found that a strain-rate- dependent double hardening matrix model can give a better prediction of the CMSX-4 behaviours. [ABSTRACT FROM AUTHOR]

The thermal effects model of slab crystal was established based on the practical operating conditions of the solid-state laser. To our knowledge, this is the first time to use the simulation software of COMSOL Multiphysics to investigate the thermal model of slab crystal with the complex boundary conditions in detail. And this is also the first time to use this theoretical method to a slab Tm:YLF laser. The results showed that thermal effects of Tm:YLF crystal were enhanced with the increase of the pump power. And the thermal effects increased sharply with the decrease of the size of the pump light along the Y-axis or the increase of the crystal doping concentration. Thermal deformation which produced by thermal lens effect played a leading role of Tm:YLF crystal. Finally, under the premise of elevated the laser output efficiency and ameliorated thermal effects, the optimized parameters were chosen which were the pump size of ω1×ω2=1mm × 6mm and doping concentration of 2.5at.%. [ABSTRACT FROM AUTHOR]

The mechanical properties of metals used as structural materials are significantly affected by hot (or warm) plastic working. Therefore, it is industrially important to predict the microscopic behaviour of materials in the deformation process during heat treatment. In this process, a number of nuclei are generated in the vicinity of grain boundaries owing to thermal fluctuation or the coalescence of subgrains, and dynamic recrystallisation (DRX) occurs along with the deformation. In this paper, we develop a DRX model by coupling a dislocation-based crystal plasticity model and a multi-phase-field (MPF) model through the dislocation density. Then, the temperature dependence of the hardening tendency in the recrystallisation process is introduced into the DRX model. A multiphysics simulation for pure Ni is conducted, and then the validity of the DRX model is investigated by comparing the numerical results of microstructure formation and the nominal stress–strain curve during DRX with experimental results. The obtained results indicate that in the process of DRX, nucleation and grain growth occur mainly around grain boundaries with high dislocation density. As deformation progresses, new dislocations pile up and subsequent nucleation occurs in the recrystallised grains. The influence of such microstructural evolution appears as oscillation in the stress–strain curve. From the stress–strain curves, the temperature dependence in DRX is observed mainly in terms of the yield stress, the hardening ratio, and the change in the hardening tendency after nucleation occurs. [ABSTRACT FROM AUTHOR]

This educational review postulates the importance of maintaining an adequate level of crystallographic education among structure-dependent scientists whose interests are not primarily in crystallography, at a time when automation and validation have made it possible to obtain high-quality structure analyses in many cases with a minimum of crystallographic background. The topics addressed are intended to form a second round of crystallographic education for a novice user whose first round involved hands-on experience with structure solution and an introduction to elementary concepts. The specific topics, chosen for their relevance as basic knowledge and their lack of emphasis in many formal treatments, are (1) crystallographic reference frames and the utility of the reciprocal cell in geometrical calculations; (2) the relationship between the two concepts that constitute our model of the crystal, namely the unit cell and the lattice; (3) the manner in which an atom is represented in concept and in practice; (4) the importance of interleaved symmetry elements required by the presence of additional symmetry on a lattice; (5) the harnessing of the natural properties of the crystalline state for the potential manipulation of properties of synthetic crystals; and (6) useful terminology for navigating a crystal structure. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional modelling of nematic liquid crystal (NLC) under the combined action of applied voltage and microwave signal is presented. The analytical method applied in the modelling is detailed. In previous research, the modelling of liquid crystal usually uses a small signal wave, and neglected its effect on the orientation of liquid crystal. In this paper, we take the microwave signal into consideration in the calculation of liquid crystal orientation, and get the influence of the power of microwave signal on the orientation. The variations of the relative permittivity of liquid crystal E7 with the power of microwave signals at 30 GHz are obtained. This method is applicable for the modelling of NLC under high power signals excitation. [ABSTRACT FROM AUTHOR]

The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A1 (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (TC = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin–phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order–disorder transition in LiTaO3. [ABSTRACT FROM AUTHOR]

There is a strategic difference between the process of cell division by mitosis in animal cells and that in cells of higher plants. One particularly puzzling feature is the absence of centrioles in plant cells, when they appear to be of central importance in the control of the process in animal cells. It is argued that in both cases the dividing cell uses the versatility of the liquid crystalline state of the mitotic cytoplasm created by the wide-scale assembly of microtubules prior to mitosis. It is not the centrioles per se which are vital – it is the director field of the mesophase which is crucial – and alternative procedures have been developed by plants and animals to create this. In both cases, they can be related to known spontaneous alignment states of liquid crystalline systems. [ABSTRACT FROM AUTHOR]

Traditionally, reconfigurable liquid crystal microwave devices that are externally electrically controlled are made using a liquid crystal sandwiched between two hard substrates with etched metal layers. Önsal, Gülnur, Onur Ugurlu, Ümit H. Kaynar, and Deniz Türsel Eliiyi, Minimization of the threshold voltage parameter of the co-doped ZnO doped liquid crystals by machine learning algorithms. Symbiotic dynamics in living liquid crystals Vats, Aditya, Pradeep Kumar Yadav, Varsha Banerjee, and Sanjay Puri, Symbiotic Dynamics in Living Liquid Crystals. [Extracted from the article]

In this paper, the mechanical properties of thermoelectric Mg2Si are investigated using molecular dynamics (MD) method, with Mg2Si in the forms of bulk, nanofilm, and nanowire, respectively. The effects of the Mg vacancy on the mechanical properties of Mg2Si in these three forms are studied in details. First of all, the equilibrium state of Mg2Si is simulated after choosing the proper potential function, boundary conditions, and the speed algorithm. Nondimensionalization is also implemented during the simulations. This part of simulation aims to verify the correctness of the crystal model established via the use of the molecular dynamics analysis. Next, the models of Mg2Si in the forms of bulk, nanofilm, and nanowire are established with different Mg vacancy proportions, and then the mechanical properties of each model are studied via the uniaxial tensile test. Finally, the stress–strain curve and subsequently the ultimate tensile strength are obtained for each model. Simulation results indicate that the ultimate tensile strength of Mg2Si in each model is decreased with the increase of the Mg vacancy proportion. Moreover, through the comparison of the ultimate tensile strengths of Mg2Si bulk, nanofilm, and nanowire, it is found that low-dimensionalization significantly reduces the ultimate tensile strength of thermoelectric Mg2Si. Results obtained in this paper can provide valuable guidance to the future applications of thermoelectric devices. [ABSTRACT FROM AUTHOR]

The continuum models of two-dimensional crystal lattice of metamaterial are investigated in this paper. The equivalent classical continuum requires the introduction of frequency-dependent mass density that becomes negative or infinite near the resonance frequency. In order to avoid the frequency-dependent mass density and make the dispersive characteristic of the elastic waves propagating in the equivalent continuum approximating that of lattice wave in two-dimensional crystal lattice of metamaterial, three kinds of continuum models, namely, the multiple displacements continuum model, the strain gradient continuum model and the nonlocal strain gradient continuum model, are investigated. It is found that the nonlocal gradient continuum model may better represent the dispersive relation and the bandgap characteristics of the metamaterial by the appropriate selection of nonlocal parameters. [ABSTRACT FROM AUTHOR]

Here, we review the basic concepts and applications of the phase-field-crystal (PFC) method, which is one of the latest simulation methodologies in materials science for problems, where atomic- and microscales are tightly coupled. The PFC method operates on atomic length and diffusive time scales, and thus constitutes a computationally efficient alternative to molecular simulation methods. Its intense development in materials science started fairly recently following the work by Elder et al. [Phys. Rev. Lett. 88 (2002), p. 245701]. Since these initial studies, dynamical density functional theory and thermodynamic concepts have been linked to the PFC approach to serve as further theoretical fundamentals for the latter. In this review, we summarize these methodological development steps as well as the most important applications of the PFC method with a special focus on the interaction of development steps taken in hard and soft matter physics, respectively. Doing so, we hope to present today's state of the art in PFC modelling as well as the potential, which might still arise from this method in physics and materials science in the nearby future. [ABSTRACT FROM AUTHOR]

The article focuses on the discovered kyanites in Tanzania, which were featured at the Tucson Gem and Mineral Show in 2009. It states that the kyanite from Tanzania shows twinned crystals which was determined through x-ray diffraction. It presents photographs of twinned kyanite specimens from Tanzania, Madagascar, and one of John S. White.

Using the crystal structures of inhibitors bound to either group-2 or group-1 neuraminidases (NAs), AScore/ShapeDock (GaDock) scoring was shown to identify the binding modes in agreement with the experiment for all inhibitors docked in their own NA/inhibitor crystal structures. To investigate the effect of small changes in protein structure on predicted binding modes, in a set of 132 docking experiments (11 inhibitors docked in 12 group-2 NA structures), AScore/ShapeDock (GaDock) identified the correct binding modes of 116 complexes. In a total of 88 docking experiments (8 inhibitors docked in 11 group-1 NA structures), AScore/ShapeDock predicted 80 binding modes correctly. Flexible AScore/ShapeDock docking, as quite reproducible, is suggested to be convenient for designing novel H5N1 inhibitors. [ABSTRACT FROM AUTHOR]

A novel Cu (II) complex with α-furan carboxylate and 2,2'-bispyridine, [Cu(fura)2(bpy)(H2O)], was synthesized. Its crystal structure was determined by X-ray diffraction analysis, and it belongs to the monoclinic system and space group P2(1)/c with CuO3N2 architecture. The crystal structural unit constructs distorted quadrangle pyramid geometry. The fluorescent and thermal properties of the complex were also studied. [ABSTRACT FROM AUTHOR]