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We report fabrication of large-scale homogeneous crystallization of CH3NH3PbBr3 (MAPbBr3) in the patterned substrate by a two-dimensional (2D) grating. This achieves high-quality optotelectronic structures on local sites in the micron scales and a homogeneous thin-film device in a centimeter scale, proposing a convenient technique to overcome the challenge for producing large-area thin-film devices with high quality by spin-coating. Through matching the concentration of the MAPbBr3/DMF solutions with the periods of the patterning structures, we found an optimized size of the patterning channels for a specified solution concentration (e.g., channel width of 5 μm for a concentration of 0.14 mg/mL). Such a design is also an excellent scheme for random lasing, since the crystalline periodic networks of MAPbBr3 grids are multi-crystalline constructions, and supply strong light-scattering interfaces. Using the random lasing performance, we can also justify the crystallization qualities and reveal the responsible mechanisms. This is important for the design of large-scale optoelectronic devices based on thin-film hybrid halide perovskites.

Focused beams of helium ions are a powerful tool for high-fidelity machining with spatial precision below 5 nm. Achieving such a high patterning precision over large areas and for different materials in a reproducible manner, however, is not trivial. Here, we introduce the Python toolbox FIB-o-mat for automated pattern creation and optimization, providing full flexibility to accomplish demanding patterning tasks. FIB-o-mat offers high-level pattern creation, enabling high-fidelity large-area patterning and systematic variations in geometry and raster settings. It also offers low-level beam path creation, providing full control over the beam movement and including sophisticated optimization tools. Three applications showcasing the potential of He ion beam nanofabrication for two-dimensional material systems and devices using FIB-o-mat are presented.

The handaxe is an iconic stone tool form used to define and symbolise both the Acheulean and the wider Palaeolithic. There has long been debate around the extent of its morphological variability between sites, and the role that extrinsic factors (especially raw material, blank type, and the extent of resharpening) have played in driving this variability, but there has been a lack of high-resolution examinations of these factors in the same study. In this paper, we present a 2D geometric morphometric analysis of 1097 handaxes from across Africa, the Levant, and western Europe to examine the patterning of this variability and what it can tell us about hominin behaviour. We replicate the findings of previous studies, that handaxe shape varies significantly between sites and entire continental regions, but we find no evidence for raw material, blank type, or resharpening in determining this pattern. What we do find, however, is that markers of reduction trajectory vary substantially between sites, suggesting that handaxes were deployed differently according to hominin need at a given site. We argue this is reflective of a continuum of reduction strategies, from those focused on the maintenance of a sharp cutting edge (i.e. direct use in cutting activities), to those focused on maintaining tip shapes, and perhaps a corresponding production of flakes. Implications for hominin behavioural flexibility are discussed.

Manipulating the distribution of functional particles in a polymer matrix can enable the fabrication of multifunctional smart composite devices. Using an acoustic field for particle patterning is a promising technique to alleviate the need for electrically conductive particles or magnetically responsive particles. To better understand the acoustic particle patterning process, a 3D high-fidelity multiphysics model is generally utilized. However, thousands of forward simulations are often required to determine a suitable set of input parameters for a desired particle pattern. It is advantageous to replace the computationally expensive forward simulation model with a cheaper-to-evaluate surrogate model to optimize the acoustic particle patterning process. This work develops a physics-informed machine learning approach to build a surrogate model capable of predicting the acoustic pressure pattern, which is highly related to the particle pattern. The surrogate model has an encoder–decoder structure, and the model training uses simulation data generated from a 3D multiphysics model. The multiphysics model is validated against experimental data before the generation of the simulation data. Physical knowledge is incorporated into the encoder–decoder model through a physics-informed input derived from the output of a 2D multiphysics model. This 2D model is constructed based on a cut plane of the 3D model to preserve most of the acoustic pressure information from the complex 3D model while being more efficient to evaluate and suitable for online prediction. The proposed physics-informed encoder–decoder model can increase the quality of the acoustic pattern prediction by over 40% compared to the base encoder–decoder model. Incorporating the physics-informed input into the base encoder–decoder can significantly reduce the sample size and model complexity required for achieving a given acoustic pattern prediction accuracy. This work provides a guideline for developing physics-informed machine learning models for manufacturing processes.

Two-dimensional (2D) heterostructures based on the combination of transition metal dichalcogenides (TMDs) and transition metal oxides (TMOs) have aroused growing attention due to their integrated merits of both components and multiple functionalities. However, nondestructive approaches of constructing TMD-TMO heterostructures are still very limited. Here, we develop a novel type of lateral TMD-TMO heterostructure (NbS 2 -Nb 2 O 5 -NbS 2 ) using a simple lithography-free, direct laser-patterning technique. The perfect contact of an ultrathin TMO channel (Nb 2 O 5 ) with two metallic TMDs (NbS 2 ) electrodes guarantee strong electrical signals in a two-terminal sensor. Distinct from sensing mechanisms in separate TMOs or TMDs, this sensor works based on the modulation of surface conduction of the ultrathin TMO (Nb 2 O 5 ) channel through an adsorbed layer of water molecules. The sensor thus exhibits high selectivity and ultrahigh sensitivity for room-temperature detection of NH 3 (Δ R / R = 80% at 50 ppm), superior to the reported NH 3 sensors based on 2D materials, and a positive temperature coefficient of resistance as high as 15%–20%/°C. Bending-invariant performance and high reliability are also demonstrated in flexible versions of sensors. Our work provides a new strategy of lithography-free processing of novel TMD-TMO heterostructures towards high-performance sensors, showing great potential in the applications of future portable and wearable electronics.

Thermal scanning probe lithography (tSPL) is a nanofabrication method for the chemical and physical nanopatterning of a large variety of materials and polymer resists with a lateral resolution of 10 nm and a depth resolution of 1 nm. In this Primer, we describe the working principles of tSPL and highlight the characteristics that make it a powerful tool to locally and directly modify material properties in ambient conditions. We introduce the main features of tSPL, which can pattern surfaces by locally delivering heat using nanosized thermal probes. We define the most critical patterning parameters in tSPL and describe post-patterning analysis of the obtained results. The main sources of reproducibility issues related to the probe and the sample as well as the limitations of the tSPL technique are discussed together with mitigation strategies. The applications of tSPL covered in this Primer include those in biomedicine, nanomagnetism and nanoelectronics; specifically, we cover the fabrication of chemical gradients, tissue-mimetic surfaces, spin wave devices and field-effect transistors based on two-dimensional materials. Finally, we provide an outlook on new strategies that can improve tSPL for future research and the fabrication of next-generation devices.Thermal scanning probe lithography (tSPL) is a nanofabrication method for the chemical and physical nanopatterning of a large variety of materials and polymer resists. Riedo and colleagues introduce the main features of tSPL, define the most critical patterning parameters and describe post-patterning analysis of the obtained results.

Spatial patterning is a key natural history attribute of sessile organisms that frequently emerges from and dictates potential for interactions among organisms. We tested whether bunchgrasses, the dominant plant functional group in longleaf pine savanna groundcover communities, are nonrandomly patterned by characterizing the spatial dispersion of three bunchgrass species across six sites in Louisiana and Florida. We mapped bunchgrass tussocks of >5.0 cm basal diameter in three 3 × 3−m plots at each site. We modeled tussocks as two-dimensional objects to analyze their spatial relationships while preserving sizes and shapes of individual tussocks. Tussocks were overdispersed (more regularly spaced than random) for all species and sites at the local interaction scale (<0.3 m). This general pattern likely arises from a tussock-centered, distance-dependent mechanism, for example, intertussock competition. Nonrandom spatial patterns of dominant species have implications for community assembly and ecosystem function in tussock-dominated grasslands and savannas, including those characterized by extreme biodiversity.

Molecular intercalation-based electrochemical exfoliation of two-dimensional (2D) materials can be used to create van der Waals heterostructures. However, the scalable assembly of vertical heterostructures typically requires the use of various chemical solvents for photolithography and subsequent transfer, which can leave behind chemical residues and limit the patterning resolution. We show that patterned van der Waals heterostructures can be fabricated from electrochemically exfoliated 2D flakes using a photoreactive crosslinker. When a 2D van der Waals percolated network with the crosslinker is exposed to ultraviolet light, the network junctions form covalent bonds, thereby enabling improved charge transport and orthogonal patterning of vertically stacked van der Waals thin-film networks without affecting the underlying prepatterned layers. Our approach can be used to create wafer-scale arrays of photopatterned field-effect transistors based on different 2D materials. The field-effect transistors exhibit high spatial uniformity and can be used to create logic gates, namely NOT, NAND and NOR gates. A photoreactive crosslinker can be used to directly pattern thin films of exfoliated two-dimensional flakes, and the technique can be performed sequentially to create patterned van der Waals heterostructures at wafer scales.

Vascular tissue in plants provides a resource distribution network for water and nutrients that exhibits remarkable diversity in patterning among different species. In many succulent plants, the vascular network includes longitudinally-oriented supplemental vascular bundles (SVBs) in the central core of the succulent stems and roots in addition to the more typical zone of vascular tissue development (vascular cambium) in a cylinder at the periphery of the succulent organ. Plant SVBs evolved in over 38 plant families often in tandem with evolutionary increases in stem and root parenchyma storage tissue, so it is of interest to understand the evolutionary-developmental processes responsible for their recurrent evolution and patterning. Previous mathematical models have successfully recreated the two-dimensional vascular patterns in stem and root cross sections, but such models have yet to recreate three-dimensional vascular patterning. Here, a stochastic reaction-diffusion model of plant vascular bundle patterning is developed in an effort to highlight a potential mechanism of three dimensional patterning-Turing pattern formation coupled with longitudinal efflux of a regulatory molecule. A relatively simple model of four or five molecules recreated empirical SVB patterns and many other common vascular arrangements. SVBs failed to develop below a threshold width of parenchymatous tissues, suggesting a mechanism of evolutionary character loss due to changes in the spatial context in which development takes place. Altered diffusion rates of the modeled activator and substrate molecules affected the number and size of the simulated SVBs. This work provides a first mathematical model employing a stochastic Turing-type mechanism that recreates three dimensional vascular patterns seen in plant stems. The model offers predictions that can be tested using molecular-genetic approaches. Evolutionary-developmental ramifications concerning evolution of diffusion rates, organ size and geometry are discussed.

Pattern formation along the animal-vegetal (AV) axis in sea urchin embryos is initiated when canonical Wnt (cWnt) signaling is activated in vegetal blastomeres. The mechanisms that restrict cWnt signaling to vegetal blastomeres are not well understood, but there is increasing evidence that the egg's vegetal cortex plays a critical role in this process by mediating localized \"activation\" of Disheveled (Dsh). To investigate how Dsh activity is regulated along the AV axis, sea urchin-specific Dsh antibodies were used to examine expression, subcellular localization, and post-translational modification of Dsh during development. Dsh is broadly expressed during early sea urchin development, but immunolocalization studies revealed that this protein is enriched in a punctate pattern in a novel vegetal cortical domain (VCD) in the egg. Vegetal blastomeres inherit this VCD during embryogenesis, and at the 60-cell stage Dsh puncta are seen in all cells that display nuclear β-catenin. Analysis of Dsh post-translational modification using two-dimensional Western blot analysis revealed that compared to Dsh pools in the bulk cytoplasm, this protein is differentially modified in the VCD and in the 16-cell stage micromeres that partially inherit this domain. Dsh localization to the VCD is not directly affected by disruption of microfilaments and microtubules, but unexpectedly, microfilament disruption led to degradation of all the Dsh pools in unfertilized eggs over a period of incubation suggesting that microfilament integrity is required for maintaining Dsh stability. These results demonstrate that a pool of differentially modified Dsh in the VCD is selectively inherited by the vegetal blastomeres that activate cWnt signaling in early embryos, and suggests that this domain functions as a scaffold for localized Dsh activation. Localized cWnt activation regulates AV axis patterning in many metazoan embryos. Hence, it is possible that the VCD is an evolutionarily conserved cytoarchitectural domain that specifies the AV axis in metazoan ova.