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Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms communities. Moiré photonic and optical lattices — two-dimensional twisted patterns lie somewhere in between perfect periodic structures and aperiodic ones — are a new emerging investigative tool for studying nonlinear localized waves of diverse types. Herein, a theory of two-dimensional spatial localization in nonlinear periodic systems with fractional-order diffraction (linear nonlocality) and moiré optical lattices is investigated. Specifically, the flat-band feature is well preserved in shallow moiré optical lattices which, interact with the defocusing nonlinearity of the media, can support fundamental gap solitons, bound states composed of several fundamental solitons, and topological states (gap vortices) with vortex charge s = 1 and 2, all populated inside the finite gaps of the linear Bloch-wave spectrum. Employing the linear-stability analysis and direct perturbed simulations, the stability and instability properties of all the localized gap modes are surveyed, highlighting a wide stability region within the first gap and a limited one (to the central part) for the third gap. The findings enable insightful studies of highly localized gap modes in linear nonlocality (fractional) physical systems with shallow moiré patterns that exhibit extremely flat bands. [ABSTRACT FROM AUTHOR]

To examine the pore structure characteristics of sandy silt in metro tunnel surrounding rock, the pore size distribution patterns and fractal dimension of sandy silt samples were determined through small-angle X-ray scattering (SAXS) experiments. This study also explored the relationship between the internal microscale pore structure of sandy silt and its macroscopic behavior. The results show that spherical pores within sandy silt predominantly exist in the forms of micropores and mesopores, with a concentrated distribution in the pore size range of 20–50 nm. Moreover, for scatterers with shapes like ellipsoids and disks, a smaller ratio of height to diameter or major axis to minor axis corresponds to a narrower range in observed pore diameter distribution, accompanied by a higher volume fraction. Meanwhile, the fractal dimensions for sandy silt samples B-1, B-2, and B-3 were 2.33, 2.33, and 2.38, respectively, aligning with the range of 2–3. The augmentation of fractal dimension corresponds to heightened surface irregularity or roughness, indicating a moderately smooth sandy silt surface. Additionally, the results show that the various deformation and strength characteristics possessed by the soil can be considered as a comprehensive reflection of the adjustment and evolution of its internal microscale pore structure elements. By utilizing the pore size distribution features and fractal dimension of the internal pore structure, a quantitative relationship between the internal pore structure of sandy silt and its macroscopic permeability or mechanical properties can be established. [ABSTRACT FROM AUTHOR]

In this research, optical absorption regulation of Ag nanodisc arrays in a monolayer MoS2 hybrid system is investigated using the FDTD technique. Ag nanodisc arrays are designed on monolayer MoS2 on SiO2/Si and Au/SiO2 substrates. For Ag/1L MoS2/SiO2/Si, two absorption peaks near 620 nm and 670 nm are showed, with different intensification amplitudes of absorption peaks and slight shifts in peak position changing diameters or spacing of Ag nanodiscs. When the diameter is 220 nm, the strongest absorption peak is displayed at 745 nm. When the spacing s is 300 nm, the absorption peak at 759 nm has the highest intensity. When the thickness of the SiO2 film increases from 90 to 280 nm and 300 nm, the intensity of the absorption peak near 620 nm increases by 1.7 times, and the peak blueshifts to 585 nm. In the band from 550 to 700 nm, the presence of the Ag nanodisc array significantly enhances the absorption of the film system, when the thickness of the SiO2 film is 300 nm, and the enhancement amplitude of the absorption peak near 620 nm reaches three times. For Ag/1L MoS2/Au/SiO2, when the diameter or spacing of the Ag nanodisc increases from 100 to 220 nm every 30 nm, the peak positions of 620 nm and 670 nm are changed. When the diameter of the Ag nanodisc is 100 nm and 220 nm, the normalized absorption rates at 686 nm and 707 nm are 0.95 and 0.96, respectively. When the spacing s is 200 nm and 400 nm, the normalized absorption rates at 562 nm and 686 nm are 0.94 and 0.96, respectively. By comparing the optical absorption with and without the Ag nanodisc array, the absorption of the monolayer MoS2 hybrid system is greatly enhanced. When the surrounding medium is changed from air to water, the absorption peaks of 641 nm and 686 nm become 587 nm and 775 nm, the distance between peak positions is enlarged, and the intensity is obviously weakened, which is due to the weakening of the surface plasmon effect of the Ag nanodisc array. [ABSTRACT FROM AUTHOR]

Highlights: A flexible tribotronic artificial synapse with bioinspired neurosensory behaviour was demonstrated, which establishes an active interaction mechanism with the environment. The device can well exhibit tuneable synaptic behaviours by changing the mechanical input modes, including excitatory postsynaptic current, paired-pulse facilitation, and the hierarchical memorial process. The device has excellent mechanical flexibility that can exhibit stable synaptic functions even under strain conditions with a bending radius of 20 mm after 1000 bending cycles. As key components of artificial afferent nervous systems, synaptic devices can mimic the physiological synaptic behaviors, which have attracted extensive attentions. Here, a flexible tribotronic artificial synapse (TAS) with bioinspired neurosensory behavior is developed. The triboelectric potential generated by the external contact electrification is used as the ion-gel-gate voltage of the organic thin film transistor, which can tune the carriers transport through the migration/accumulation of ions. The TAS successfully demonstrates a series of synaptic behaviors by external stimuli, such as excitatory postsynaptic current, paired-pulse facilitation, and the hierarchical memory process from sensory memory to short-term memory and long-term memory. Moreover, the synaptic behaviors remained stable under the strain condition with a bending radius of 20 mm, and the TAS still exhibits excellent durability after 1000 bending cycles. Finally, Pavlovian conditioning has been successfully mimicked by applying force and vibration as food and bell, respectively. This work demonstrates a bioinspired flexible artificial synapse that will help to facilitate the development of artificial afferent nervous systems, which is great significance to the practical application of artificial limbs, robotics, and bionics in future. [ABSTRACT FROM AUTHOR]

Electromagnetically induced optical (or photonic) lattices via atomic coherence in atomic ensembles have recently received great theoretical and experimental interest. We here conceive a way to generate electromagnetically induced moiré optical lattices — a twisted periodic pattern when two identical periodic patterns (lattices) are overlapped in a twisted angle (θ) — in a three-level coherent atomic gas working under electromagnetically induced transparency. We show that, changing the twisted angle and relative strength between the two constitutive sublattices, the moiré Bloch bands that are extremely flattened can always appear, resembling the typical flat-band and moiré physics found in other contexts. Dynamics of light propagation in the induced periodic structures demonstrating the unique linear localization and delocalization properties are also revealed. Our scheme can be implemented in a Rubidium atomic medium, where the predicted moiré optical lattices and flattened bands are naturally observable. [ABSTRACT FROM AUTHOR]

In this work, conical cavities with a fixed top diameter and varied bottom diameter have been utilized to improve the signal intensity, signal-to-noise ratio (SNR), and signal stability of laser-induced breakdown spectroscopy (LIBS). It is observed that the postponement of the maximum enhancement of spectral intensity and SNR occurs abnormally with decreasing the bottom diameter due to the energy dissipation from the plasma to the cavity walls. Optimization of the cavity size indicates that the conical cavity is superior to the widely-used cylindrical cavity in improving the performance of LIBS. It is also found that the emission enhancement in the conical cavity with larger bottom diameters is attributed to the increase in plasma temperature and electron number density, but the enhancement in the conical cavity with smaller bottom diameters is ascribed to the growth of electron number density. For the first time, the exact efficiencies of conical cavities suppressing the total number density fluctuation are acquired to evaluate the performance of improving signal stability through analysis of the signal uncertainty composition. [ABSTRACT FROM AUTHOR]

Carbon materials have become a research hotspot in many fields because of their unique properties. In this paper, carbon nanowires (CNWs) were constructed with the finite-difference time-domain (FDTD) technique, and the effects of different structural parameters on the optical absorption properties of CNWS arrays at 350–810 nm were investigated. The results show that different lengths, diameters and spacings of the nanowires lead to different absorption properties of the arrays. In addition to a sharp decrease in the absorption at high incidence or viewing angles, the arrays have strong absorption properties at other angles. However, the array absorption at high incidence or viewing angles can be enhanced to some extent by varying the lengths of the nanowires. The wavelength and polarization direction of the excitation light have little effect on the absorption properties of the arrays. It is very important to determine the corresponding structural parameters of CNWs with the strongest absorption for the fabrication of nanowire arrays and their applications in stealth technologies, nanolight-emitting devices, photoelectric sensors and photovoltaic cells. [ABSTRACT FROM AUTHOR]

We numerically investigated the impact of the excitation wavelength and metal film thickness on second-harmonic generation (SHG) in bulk MoS2, which originates from the change in optical-path difference and phase difference among the multistage reflected lights during the thin-film interference process. The enhancement factor of SHG for a MoS2 layer on metal-dielectric substrates was calculated using the finite-difference time-domain technique. It was shown that the intensity of SHG was strongly affected by the excitation wavelength and the thickness of the metal film. We also obtained the dependence of the thickness of the MoS2 layer with the strongest SHG on the excitation wavelength. The reflection, transmission, and absorption of MoS2 layers with different thicknesses were studied by changing the metal film thickness of substrates, and the MoS2 thickness with the strongest SHG was found at different excitation wavelengths. We found that changing the metal film thickness has little effect on the color of the MoS2 layer, indicating that the thickness of the MoS2 layer can still be roughly estimated from the color. Therefore, it is inferred that MoS2 layers with the strongest SHG have the potential to be used for optical information storage or in the design of optical devices provided that the excitation wavelength or the thickness of the metal film is selected appropriately. [ABSTRACT FROM AUTHOR]

Myostatin (MSTN), a member of the transforming growth factor-β superfamily, is a negative regulator of muscle growth and development. Disruption of the MSTN gene in various mammalian species markedly promotes muscle growth. Previous studies have mainly focused on the disruption of the MSTN peptide coding region in pigs but not on the modification of the signal peptide region. In this study, the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9) system was used to successfully introduce two mutations (PVD20H and GP19del) in the MSTN signal peptide region of the indigenous Chinese pig breed, Liang Guang Small Spotted pig. Both mutations in signal peptide increased the muscle mass without inhibiting the production of mature MSTN peptide in the cells. Histological analysis revealed that the enhanced muscle mass in MSTN+/PVD20H pig was mainly due to an increase in the number of muscle fibers. The expression of MSTN in the longissimus dorsi muscle of MSTN+/PVD20H and MSTNKO/PVD20H pigs was significantly downregulated, whereas that of myogenic regulatory factors, including MyoD, Myogenin, and Myf-5, was significantly upregulated when compared to those in the longissimus dorsi muscle of wild-type pigs. Meanwhile, the mutations also activated the PI3K/Akt pathway. The results of this study indicated that precise editing of the MSTN signal peptide can enhance porcine muscle development without markedly affecting the expression of mature MSTN peptide, which could exert other beneficial biological functions in the edited pigs. [ABSTRACT FROM AUTHOR]

The deformation of a bloom tube mold was investigated using an in-house-developed complex model considering the flow, heat transfer, and solidification as well as the copper tube stress strain. This model was validated by the cooling water temperature rise, solidification shell thickness, copper oxidized zone, and measured copper deformation. Based on this model, the heat transfer characteristics of the mold were analyzed. The deformation trends of the copper tube under different water pressures were compared. The results revealed that the deformation of the wide copper plate was mainly influenced by the cooling water pressure, whereas the deformation on the narrow side was primarily affected by the temperature field. Similarly, the corner distortion of the copper plate resulted mainly from the deformation of the wide and the narrow copper plates. [ABSTRACT FROM AUTHOR]

Self-trapped modes suffer critical collapse in two-dimensional cubic systems. To overcome such a collapse, linear periodic potentials or competing nonlinearities between self-focusing cubic and self-defocusing quintic nonlinear terms are often introduced. Here, we combine both schemes in the context of an unconventional and nonlinear fractional Schrödinger equation with attractive-repulsive cubic–quintic nonlinearity and an optical lattice. We report theoretical results for various two-dimensional trapped solitons, including fundamental gap and vortical solitons as well as the gap-type soliton clusters. The latter soliton family resembles the recently-found gap waves. We uncover that, unlike the conventional case, the fractional model exhibiting fractional diffraction order strongly influences the formation of higher band gaps. Hence, a new route for the study of self-trapped modes in these newly emergent higher band gaps is suggested. Regimes of stability and instability of all the soliton families are obtained with the help of linear-stability analysis and direct simulations. Stabilising localised solitons in higher dimensions is more challenging than their one dimensional counterpart due to the onset of critical collapse. Here, competing nonlinear terms are added to a linearly-modulated optical lattice to predict regimes of stability for different soliton families. [ABSTRACT FROM AUTHOR]

Aims: The present study aimed to evaluate whether the non-Smad dependent TAK1 signaling pathway (BMP-2-TAK1-p38-Osx signaling pathway) played an important role in bone repair mediated by hollow hydroxyapatite (HA) microspheres/chitosan (CS) composite. Methods: Firstly, the biological activity of rhBMP-2 released from the complex was investigated. Then, differentiation test of osteoblasts including ALP activity and calcium deposition, X-ray scoring and three-point bending test were performed. Finally, the mRNAs expression of TAK1, p38, Osx and osteogenic markers was tested by reverse transcription-polymerase chain reaction (RT-PCR). Results: RhBMP-2 could be loaded and released from the complex in bioactive form. Additionally, the complex provided a prolonged period of time compared with HA/CS scaffolds. Serum ALP activity was significantly decreased in the TAK1 inhibitor group and p38 inhibitor group. In the X-ray radiography, bone callus was observed in rhBMP-2-loaded hollow HA microspheres/CS composite group. In the three-point bending test, load values in p38 inhibitor group decreased. In the animal model, the mRNA expression of BSP on day 90 was significantly decreased in the p38 inhibitor group and TAK1 inhibitor group. In MC3T3-E1 cells, the mRNA expression of OSX was remarkably up-regulated in both rhBMP-2 group or rhBMP-2-loaded hollow HA microspheres/CS composite group; while the mRNA expression of OSX was significantly down-regulated in TAK1 inhibitor group and p38 inhibitor group. Conclusion: The BMP-2-TAK1-p38-OSX signaling pathway may play an important role in bone formation and repair mediated by rhBMP-2-loaded hollow HA microspheres/CS composite. [ABSTRACT FROM AUTHOR]

Competing nonlinearities, such as the cubic (Kerr) and quintic nonlinear terms whose strengths are of opposite signs (the coefficients in front of the nonlinearities), exist in various physical media (in particular, in optical and matter-wave media). A benign competition between self-focusing cubic and self-defocusing quintic nonlinear nonlinearities (known as cubic–quintic model) plays an important role in creating and stabilizing the self-trapping of D-dimensional localized structures, in the contexts of standard nonlinear Schrödinger equation. We incorporate an external periodic potential (linear lattice) into this model and extend it to the space-fractional scenario that begins to surface in very recent years—the nonlinear fractional Schrödinger equation (NLFSE), therefore obtaining the cubic–quintic or the purely quintic NLFSE, and investigate the propagation and stability properties of self-trapped modes therein. Two types of one-dimensional localized gap modes are found, including the fundamental and dipole-mode gap solitons. Employing the techniques based on the linear-stability analysis and direct numerical simulations, we get the stability regions of all the localized modes; and particularly, the anti-Vakhitov–Kolokolov criterion applies for the stable portions of soliton families generated in the frameworks of quintic-only nonlinearity and competing cubic–quintic nonlinear terms. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor 2 (IGF2) plays an important role in the development of the foetus and in post-natal growth and development. A SNP within intron 3 of porcine IGF2 disrupts a binding site for the repressor, zinc finger BED-type containing 6 (ZBED6), leading to up-regulation of IGF2 in skeletal muscle and major effects on muscle growth, heart size, and fat deposition. This favourable mutation is common in Western commercial pig populations, but is not present in most indigenous Chinese pig breeds. Here, we described the efficient disruption of the ZBED6 binding site motif in intron 3 of IGF2 by CRISPR/Cas9 in porcine embryonic fibroblasts (PEFs) from the indigenous Chinese pig breed, Liang Guang Small Spotted pig. Disruption of the binding motif led to a drastic up-regulation of IGF2 expression in PEFs and enhanced myogenic potential and cell proliferation of PEFs. IGF2-edited pigs were then generated using somatic cell nuclear transfer. Enhanced muscle development was evident in one pig with biallelic deletion of the ZBED6 binding site motif, implying that the release of ZBED6 repression has a major effect on porcine muscle development. Our study confirmed the important effect of a mutation in the ZBED6 binding site motif on IGF2 expression and myogenesis, thus providing the basis for breeding a new line of Liang Guang Small Spotted pigs with improved lean meat percentage, a trait of great commercial value to pig producers. [ABSTRACT FROM AUTHOR]

Graphene is widely employed to improve the overall thermal conductivity of polymer composites because of its remarkable thermal conductivity. However, the magnitude of its improvement of thermal conductivity is far below the values expected from the remarkably high thermal conductivity of graphene and is very much less than the production cost of graphene, greatly limiting its large-scale applications in the field of thermal management. Therefore, understanding heat transport behaviors within the polymer composites and studying the related influential factors are very important. Here, heat transport behaviors within few-layer graphene (FLG)/epoxy composites are studied using molecular dynamics (MD) simulations. The influences of interfacial thermal resistance, FLG volume fraction and FLG length on overall thermal conductivity of the composites are specifically analyzed, finding that there is a significant interfacial thermal resistance between FLG and epoxy because of the mismatch of the phonon vibration power spectrum (VPS). Furthermore, the interfacial thermal resistance, FLG volume fraction, and FLG length play important roles in improving the overall thermal conductivity of FLG/epoxy composites. Our findings provide a better understanding of the heat transport behaviors within polymer composites and should be useful for future development of various thermal management applications. [ABSTRACT FROM AUTHOR]

The nonlinear lattice - a new and nonlinear class of periodic potentials - was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional (2D) solitons against their intrinsic critical collapse in Kerr media. Here, we provide a possibility for supporting 2D matter-wave solitons and vortices in an extended setting - the cubic and quintic model - by introducing another nonlinear lattice whose period is controllable and can be different from its cubic counterpart, to its quintic nonlinearity, therefore making a fully 'nonlinear quasi-crystal'. A variational approximation based on Gaussian ansatz is developed for the fundamental solitons and in particular, their stability exactly follows the inverted Vakhitov-Kolokolov stability criterion, whereas the vortex solitons are only studied by means of numerical methods. Stability regions for two types of localized mode - the fundamental and vortex solitons - are provided. A noteworthy feature of the localized solutions is that the vortex solitons are stable only when the period of the quintic nonlinear lattice is the same as the cubic one or when the quintic nonlinearity is constant, while the stable fundamental solitons can be created under looser conditions. Our physical setting (cubic-quintic model) is in the framework of the Gross-Pitaevskii equation or nonlinear Schrödinger equation, the predicted localized modes thus may be implemented in Bose-Einstein condensates and nonlinear optical media with tunable cubic and quintic nonlinearities. [ABSTRACT FROM AUTHOR]

The effective photonic control is one of the key issues in photo-physics. Significant advancement in photonic crystals, quantum optics, ultrafast optics as well as micro-nano-optics gives rise to new opportunities to manipulate the emission and propagation in optical fields, leading to a number of new and interesting discoveries, e.g., ultrashort light pulse storage and efficient energy conversion. This paper reviews the latest research progress in storage, release and energy conversion for ultrashort laser pulses in periodical arrays of absorbing medium. Techniques to fabricate such devices are also presented. [ABSTRACT FROM AUTHOR]