Band gap engineering of atomically thin two-dimensional layered materials is critical for their applications in nanoelectronics, optoelectronics, and photonics. Here we report, for the first time, a simple one-step chemical vapor deposition approach for the simultaneous growth of alloy MoS2xSe2(1-x) triangular nanosheets with complete composition tunability. Both the Raman and the photoluminescence studies show tunable optical properties consistent with composition of the alloy nanosheets. Importantly, all samples show a single bandedge emission peak, with the spectral peak position shifting from 668 nm (for pure MoS2) to 795 nm (for pure MoSe2), indicating the high quality for these complete composition alloy nanosheets. These band gap engineered 2D structures could open up an exciting opportunity for probing their fundamental physical properties in 2D and may find diverse applications in functional electronic/optoelectronic devices.

In Arabidopsis thaliana, signal transduction of the hormone ethylene involves at least two receptors, ETR1 and ERS, both of which are members of the two-component histidine protein kinase family that is prevalent in prokaryotes. The pathway also contains a negative regulator of ethylene responses, CTR1, which closely resembles members of the Raf protein kinase family. CTR1 is thought to act at or downstream of ETR1 and ERS based on double mutant analysis; however, the signaling mechanisms leading from ethylene perception to the regulation of CTR1 are unknown. By using the yeast two-hybrid assay, we detected a specific interaction between the CTR1 amino-terminal domain and the predicted histidine kinase domain of ETR1 and ERS. We subsequently verified these interactions by using an in vitro protein association assay(s). In addition, we determined that the amino-terminal domain of CTR1 can associate with the predicted receiver domain of ETR1 in vitro. Based on deletion analysis, the portion of CTR1 that interacts with ETR1 roughly aligns with the regulatory region of Raf kinases. These physical associations support the genetic evidence that CTR1 acts in the pathway of ETR1 and ERS and suggest that these interactions could be involved in the regulation of CTR1 activity.Ethylene has numerous effects on plant growth and development, such as fruit-ripening, organ abscission, seed germination, senescence, and the induction of certain defense responses (1). The cloning of genes corresponding to several ethylene-response mutants in Arabidopsis has begun to provide us with insight into the molecular basis of ethylene signal transduction (2-6). In Arabidopsis, there are at least two ethylene receptors, ETR1 and ERS, that are similar to each other. Plants appear to have multiple ethylene receptors; several different ETR1 and ERS homologs have been cloned recently from Arabidopsis (7) and tomato (8, 9). The ETR1 and ERS gene products are predicted to function as histidine protein kinases based on their sequence similarities with the two-component regulator family. The two-component regulators are prevalent in prokaryotes (10) and are starting to be identified in various eukaryotes, including fungi, slime mold, and higher plants (11,12); one of these, the Arabidopsis CKI1 protein, is potentially a receptor for cytokinin (13). The basic two-component system consists of a histidine autokinase sensor component that directs the activity of a cognate response regulator, which in turn controls downstream signaling (10). After autophosphorylation of the sensor kinase, the phosphoryl group is transferred from the histidine of the sensor kinase to an aspartic acid residue in the receiver domain of the response regulator (10). The ETR1 protein is an example of a hybrid histidine kinase because it contains both a histidine kinase domain and a receiver domain (2). ERS, in contrast, contains only a histidine kinase domain (3). The significance of having an attached receiver domain is unknown, and whether there are separate cognate...

Summary Activation of heterodimeric (α/β) integrin transmembrane receptors by the 270 kDa cytoskeletal protein talin is essential for many important cell adhesive and physiological responses. A key step in this process involves interaction of phosphotyrosine-binding (PTB) domain in the N-terminal head of talin (talin-H) with integrin β membrane-proximal cytoplasmic tails (β-MP-CTs). Compared to talin-H, intact talin exhibits low potency in inducing integrin activation. Using NMR spectroscopy, we show that the large C-terminal rod domain of talin (talin-R) interacts with talin-H and allosterically restrains talin in a closed conformation. We further demonstrate that talin-R specifically masks a region in talin-PTB where integrin β-MP-CT binds and competes with it for binding to talin-PTB. The inhibitory interaction is disrupted by a constitutively activating mutation (M319A) or by phosphatidylinositol 4,5-bisphosphate, a known talin activator. These data define a distinct autoinhibition mechanism for talin and suggest how it controls integrin activation and cell adhesion.

Recently, graphene-based semiconductor photocatalysts have attracted more attention because of their enhanced photocatalytic activity caused by interfacial charge transfer (IFCT). However, the effect of a chemical bond is rarely involved for the IFCT. In this work, TiO2/graphene composites with a chemically bonded interface were prepared by a facile solvothermal method using tetrabutyl orthotitanate (TBOT) as the Ti source. The chemically bonded TiO2/graphene composites effectively enhanced their photocatalytic activity in photodegradation of formaldehyde in air, and the graphene content exhibited an obvious influence on the photocatalytic activity. The prepared composite with 2.5 wt % graphene (G2.5-TiO2) showed the highest photocatalytic activity, exceeding that of Degussa P25, as-prepared pure TiO2 nanoparticles, and the mechanically mixed TiO2/graphene (2.5 wt %) composite by a factor of 1.5, 2.6, and 2.3, respectively. The enhancement in the photocatalytic activity was attributed to the synergetic effect between graphene and TiO2 nanoparticles. Other than the graphene as an excellent electron acceptor and transporter, the enhanced photocatalytic activity was caused by IFCT through a C–Ti bond, which markedly decreased the recombination of electron–hole pairs and increased the number of holes participating in the photooxidation process, confirmed by XPS analysis, the gaseous phase transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence spectra. This work about effective IFCT through a chemically bonded interface can provide new insights for directing the design of new heterogeneous photocatalysts, which can be applied in environmental protection, water splitting, and photoelectrochemical conversion.

Although great efforts have been devoted to the synthesis of halide perovskites nanostructures, vapor growth of high-quality one-dimensional cesium lead halide nanostructures for tunable nanoscale lasers is still a challenge. Here, we report the growth of high-quality all-inorganic cesium lead halide alloy perovskite micro/nanorods with complete composition tuning by vapor-phase deposition. The as-grown micro/nanorods are single-crystalline with a triangular cross section and show strong photoluminescence which can be tuned from 415 to 673 nm by varying the halide composition. Furthermore, these single-crystalline perovskite micro/nanorods themselves function as effective Fabry-Perot cavities for nanoscale lasers. We have realized room-temperature tunable lasing of cesium lead halide perovskite with low lasing thresholds (∼14.1 μJ cm) and high Q factors (∼3500).

Directional growth of ultralong nanowires (NWs) is significant for practical application of large-scale optoelectronic integration. Here, we demonstrate the controlled growth of in-plane directional perovskite CsPbBr NWs, induced by graphoepitaxial effect on annealed M-plane sapphire substrates. The wires have a diameter of several hundred nanometers, with lengths up to several millimeters. Microstructure characterization shows that CsPbBr NWs are high-quality single crystals, with smooth surfaces and well-defined cross section. The NWs have very strong band-edge photoluminescence (PL) with a long PL lifetime of ∼25 ns and can realize high-quality optical waveguides. Photodetectors constructed on these individual NWs exhibit excellent photoresponse with an ultrahigh responsivity of 4400 A/W and a very fast response speed of 252 μs. This work presents an important step toward scalable growth of high-quality perovskite NWs, which will provide promising opportunities in constructing integrated nanophotonic and optoelectronic systems.

Superparamagnetic iron oxide nanocrystals are a class of nontoxic and biodegradable nanomaterials with broad applications in science, engineering, and medicine, but there is still considerable debate on how crystalline domain size and surface chemistry influence their properties for magnetic resonance imaging (MRI). Here we examine the effects of particle size and surface chemistry by comparing proton relaxivity data for two particle sizes and three surface coatings (6 combinations). These combinations are achieved by using both direct ligand exchange and indirect encapsulation methods to solubilize oleic-acid capped iron oxide nanocrystals. The results indicate that proton relaxivity depends on the particle size, the surface coating thickness and hydrophilicity, and the coordination chemistry of inner capping ligands. Nanocrystals coated with the hydrophilic ligand polyethylenimine (PEI) yield the highest proton relaxivity, whereas nanocrystals capped with oleic acid and amphiphilic polymers exhibit the strongest dependence on particle size. These effects arise from intrinsic surface spin disorders as well as from rapid exchange (diffusion) of water molecules between the bulk phase and the adjacent layer surrounding the particle surface.

Obesity is associated with metabolic inflammation and endoplasmic reticulum (ER) stress, both of which promote metabolic disease progression. Adipose tissue macrophages (ATMs) are key players orchestrating metabolic inflammation, and ER stress enhances macrophage activation. However, whether ER stress pathways underlie ATM regulation of energy homeostasis remains unclear. Here, we identified inositol-requiring enzyme 1α (IRE1α) as a critical switch governing M1-M2 macrophage polarization and energy balance. Myeloid-specific IRE1α abrogation in Ern1; Lyz2-Cre mice largely reversed high-fat diet (HFD)-induced M1-M2 imbalance in white adipose tissue (WAT) and blocked HFD-induced obesity, insulin resistance, hyperlipidemia and hepatic steatosis. Brown adipose tissue (BAT) activity, WAT browning and energy expenditure were significantly higher in Ern1; Lyz2-Cre mice. Furthermore, IRE1α ablation augmented M2 polarization of macrophages in a cell-autonomous manner. Thus, IRE1α senses protein unfolding and metabolic and immunological states, and consequently guides ATM polarization. The macrophage IRE1α pathway drives obesity and metabolic syndrome through impairing BAT activity and WAT browning.