High-Performance Atomically-Thin Room-Temperature NO2 Sensor.

The development of room-temperature sensing devices for detecting small concentrations of molecular species is imperative for a wide range of low-power sensor applications. We demonstrate a room-temperature, highly sensitive, selective, stable, and reversible chemical sensor based on a monolayer of the transition-metal dichalcogenide Re0.5Nb0.5S2. The sensing device exhibits a thickness-dependent carrier type, and upon exposure to NO2 molecules, its electrical resistance considerably increases or decreases depending on the layer number. The sensor is selective to NO2 with only minimal response to other gases such as NH3, CH2O, and CO2. In the presence of humidity, not only are the sensing properties not deteriorated but also the monolayer sensor shows complete reversibility with fast recovery at room temperature. We present a theoretical analysis of the sensing platform and identify the atomically sensitive transduction mechanism

Radical nostalgia, progressive patriotism and Labour's 'English problem'

‘Progressive patriots’ have long argued that Englishness can form the basis of a transformative political project, whether based on an historic tradition of resistance to state power or an open and cosmopolitan identity. However, this article suggests that the politics of Englishness present a number of specific dilemmas for Labour. First the historical narrative of a radical tradition in British history is not straightforwardly English and cannot easily be used to support a competitive politics of nationhood, in the way that disaffected English identifiers might desire. Second, the deliberately alternative nature of this ‘radical nostalgic’ narrative makes it an unlikely basis for a unifying national story. It is also at odds with Labour’s status as a successful party of government, committed to using the power of the British state, rather than opposing it. Finally, while ‘everyday Englishness’ may well align with core Labour values and be less socially conservative, intolerant or racially exclusive than it is often described, its very nature as an everyday practice, rather than a political identity makes it difficult for Labour to co-opt

Sculpting Liquids with Two-Dimensional Materials: The Assembly of Ti3C2Tx MXene Sheets at Liquid–Liquid Interfaces

The self-assembly of nanoscale materials at the liquid–liquid interface allows for fabrication of three-dimensionally structured liquids with nearly arbitrary geometries and tailored electronic, optical, and magnetic properties. Two-dimensional (2D) materials are highly anisotropic, with thicknesses on the order of a nanometer and lateral dimensions upward of hundreds of nanometers to micrometers. Controlling the assembly of these materials has direct implications for their properties and performance. We here describe the interfacial assembly and jamming of Ti3C2Tx MXene nanosheets at the oil–water interface. Planar, as well as complex, programmed three-dimensional all-liquid objects are realized. Our approach presents potential for the creation of all-liquid 3D-printed devices for possible applications in all-liquid electrochemical and energy storage devices and electrically active, all-liquid fluidics that exploits the versatile structure, functionality, and reconfigurability of liquids

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Frustration and Atomic Ordering in a Monolayer Semiconductor Alloy.

Frustrated interactions can lead to short-range ordering arising from incompatible interactions of fundamental physical quantities with the underlying lattice. The simplest example is the triangular lattice of spins with antiferromagnetic interactions, where the nearest-neighbor spin-spin interactions cannot simultaneously be energy minimized. Here we show that engineering frustrated interactions is a possible route for controlling structural and electronic phenomena in semiconductor alloys. Using aberration-corrected scanning transmission electron microscopy in conjunction with density functional theory calculations, we demonstrate atomic ordering in a two-dimensional semiconductor alloy as a result of the competition between geometrical constraints and nearest-neighbor interactions. Statistical analyses uncover the presence of short-range ordering in the lattice. In addition, we show how the induced ordering can be used as another degree of freedom to considerably modify the band gap of monolayer semiconductor alloys

High-Performance Atomically-Thin Room-Temperature NO2 Sensor.

The development of room-temperature sensing devices for detecting small concentrations of molecular species is imperative for a wide range of low-power sensor applications. We demonstrate a room-temperature, highly sensitive, selective, stable, and reversible chemical sensor based on a monolayer of the transition-metal dichalcogenide Re0.5Nb0.5S2. The sensing device exhibits a thickness-dependent carrier type, and upon exposure to NO2 molecules, its electrical resistance considerably increases or decreases depending on the layer number. The sensor is selective to NO2 with only minimal response to other gases such as NH3, CH2O, and CO2. In the presence of humidity, not only are the sensing properties not deteriorated but also the monolayer sensor shows complete reversibility with fast recovery at room temperature. We present a theoretical analysis of the sensing platform and identify the atomically sensitive transduction mechanism

Sculpting Liquids with Two-Dimensional Materials: The Assembly of Ti3C2Tx MXene Sheets at Liquid-Liquid Interfaces.

The self-assembly of nanoscale materials at the liquid-liquid interface allows for fabrication of three-dimensionally structured liquids with nearly arbitrary geometries and tailored electronic, optical, and magnetic properties. Two-dimensional (2D) materials are highly anisotropic, with thicknesses on the order of a nanometer and lateral dimensions upward of hundreds of nanometers to micrometers. Controlling the assembly of these materials has direct implications for their properties and performance. We here describe the interfacial assembly and jamming of Ti3C2Tx MXene nanosheets at the oil-water interface. Planar, as well as complex, programmed three-dimensional all-liquid objects are realized. Our approach presents potential for the creation of all-liquid 3D-printed devices for possible applications in all-liquid electrochemical and energy storage devices and electrically active, all-liquid fluidics that exploits the versatile structure, functionality, and reconfigurability of liquids