Anthropogenic climate change has emerged as a critical environmental problem, prompting frequent investigations into its consequences for various ecological systems. Few studies, however, have explored the effect of climate change on ecological stability and the underlying mechanisms. We conduct a field experiment to assess the influence of warming and altered precipitation on the temporal stability of plant community biomass in an alpine grassland located on the Tibetan Plateau. We find that whereas precipitation alteration does not influence biomass temporal stability, warming lowers stability through reducing the degree of species asynchrony. Importantly, biomass temporal stability is not influenced by plant species diversity, but is largely determined by the temporal stability of dominant species and asynchronous population dynamics among the coexisting species. Our findings suggest that ongoing and future climate change may alter stability properties of ecological communities, potentially hindering their ability to provide ecosystem services for humanity.

The integration of two-dimensional (2D) van der Waals semiconductors into silicon electronics technology will require the production of large-scale, uniform, and highly crystalline films. We report a route for synthesizing wafer-scale single-crystalline 2H molybdenum ditelluride (MoTe2) semiconductors on an amorphous insulating substrate. In-plane 2D-epitaxy growth by tellurizing was triggered from a deliberately implanted single seed crystal. The resulting single-crystalline film completely covered a 2.5-centimeter wafer with excellent uniformity. The 2H MoTe2 2D single-crystalline film can use itself as a template for further rapid epitaxy in a vertical manner. Transistor arrays fabricated with the as-prepared 2H MoTe2 single crystals exhibited high electrical performance, with excellent uniformity and 100% device yield.

Among the Mo-and W-based two-dimensional (2D) transition metal dichalcogenides, MoTe 2 is particularly interesting for phase-engineering applications, because it has the smallest free energy difference between the semiconducting 2H phase and metallic 1T′ phase. In this work, we reveal that, under the proper circumstance, Mo and Te atoms can rearrange themselves to transform from a polycrystalline 1T′ phase into a single-crystalline 2H phase in a large scale. We manifest the mechanisms of the solid-to-solid transformation by conducting density functional theory calculations, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The phase transformation is well described by the time−temperature−transformation diagram. By optimizing the kinetic rates of nucleation and crystal growth, we have synthesized a single-crystalline 2H-MoTe 2 domain with a diameter of 2.34 mm, a centimeter-scale 2H-MoTe 2 thin film with a domain size up to several hundred micrometers, and a seamless 1T′−2H MoTe 2 coplanar homojunction. The 1T′−2H MoTe 2 homojunction provides an elegant solution for ohmic contact of 2D semiconductors. The controlled solid-to-solid phase transformation in 2D limit provides a new route to realize wafer-scale single-crystalline 2D semiconductor and coplanar heterostructure for 2D circuitry.

A high-performance NOT logic gate (inverter) was constructed by combining two identical n-channel metal-semiconductor field-effect transistors (MESFETs) made on a single CdS nanowire (NW). The inverter has a voltage gain as high as 83, which is the highest reported so far for inverters made on one-dimensional nanomaterials. The MESFETs used in the inverter circuit show excellent transistor performance, such as high on/off current ratio ( approximately 10(7)), low threshold voltage ( approximately -0.4 V), and low subthreshold swing ( approximately 60 mV/dec). With the assembly of three identical NW MESFETs, NOR and NAND gates have been constructed.