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Rigid, solid-state components represent the current paradigm for electronic systems, but they lack post-production reconfigurability and pose ever-increasing challenges to efficient end-of-life recycling. Liquid electronics may overcome these limitations by offering flexible in-the-field redesign and separation at end-of-life via simple liquid phase chemistries. Up to now, preliminary work on liquid electronics has focused on liquid metal components, but these devices still require an encapsulating polymer and typically use alloys of rare elements like indium. Here, using the self-assembly of jammed two-dimensional titanium carbide (Ti

Invading microbes face a myriad of cidal mechanisms of phagocytes that inflict physical damage to microbial structures. How intracellular bacterial pathogens adapt to these stresses is not fully understood. Here, we report a new virulence mechanism by which mycobacteria alter the mechanical stiffness of their cell surface to become refractory to killing during infection. Long-Term Time-Lapse Atomic Force Microscopy was used to reveal a process of “mechanical morphotype switching” in mycobacteria exposed to host intracellular stress. A “soft” mechanical morphotype switch enhances tolerance to intracellular macrophage stress, including cathelicidin. Genetic manipulation, by deletion of uvrA, or pharmacological treatment, with bedaquiline, locked mycobacteria into a “soft” mechanical morphotype state, enhancing survival in macrophages. Our study proposes microbial mechanical adaptation as a new axis for surviving host-mediated stressors.One-Sentence SummaryBacteria alter their cell surface mechanical properties to increase survival during macrophage infection.

The Lawrence Berkeley National Laboratory working group was presented with three problems involving the improvement of images from an AFM scanner. The first concerned the inpainting of an image for which data is collected via a spiral scan waveform. The second concerned the exploitation of data obtained at different times to obtain better spatial resolution. The third concerned the correction of horizontal positions reported by the sensor, particularly when the scanner is operating at high frequency. Herein is a brief report on the progress and ideas generated by the working group on each of these problems.

Copper compounds have been extensively investigated for diverse applications. However, studies of cuprous hydroxide (CuOH) have been scarce, due to structural metastability. Herein, a facile, wet-chemistry procedure is reported for the preparation of stable CuOH nanostructures via deliberate functionalization with select organic ligands, such as acetylene and mercapto derivatives. The resulting nanostructures are found to exhibit a nanoribbon morphology consisting of small nanocrystals embedded within a largely amorphous nanosheet-like scaffold. The acetylene derivatives are found to anchor onto the CuOH forming Cu-Cࣽ linkages, whereas Cu-S- interfacial bonds are formed with the mercapto ligands. Effective electronic coupling occurs at the ligand-core interface in the former, in contrast to mostly non-conjugated interfacial bonds in the latter, as manifested in spectroscopic measurements and confirmed in theoretical studies based on first principles calculations. Notably, the acetylene-capped CuOH nanostructures exhibit markedly enhanced photodynamic activity in the inhibition of bacteria growth, as compared to the mercapto-capped counterparts, due to a reduced material bandgap and effective photocatalytic generation of reactive oxygen species. Results from this study demonstrate that deliberate structural engineering with select organic ligands is an effective strategy in the stabilization and functionalization of CuOH nanostructures, a critical first step in exploring their diverse applications. This article is protected by copyright. All rights reserved.

This chapter contends that the Western Hemisphere is not only key to the development of U.S. national security but also remains of great importance today. Quite simply, U.S. national security interests grew firstly within their own “neighborhood,” and those interests continue to be both important and complex into the present day. Crucially, this is where national security threats come into direct contact with the U.S. homeland. Understanding this history and these interactive dynamics is important to the analysis of contemporary national security questions in the Western Hemisphere. The chapter focuses on key issues that are deeply intertwined: economics and trade; democracy, development, and human rights; drugs and transnational threats; and homeland security and homeland defense.

Since the period of negotiations for and signing of the North American Free Trade Agreement (NAFTA), the United States has focused policy efforts towards Mexico on two macro-goals: deepening economic integration and increasing border security. This article contends that these two goals appear to be paradoxical. It shows that cross-border economic interaction has grown alongside a discursive and hard policy focus on US border security policies to meet various “threats.” Engaging with policy detail of the Merida Initiative, it argues that the US aims to overcome this paradox by treating the whole NAFTA area as a shared economic and security space, and pushing concepts of “homeland security” beyond its frontiers. The article concludes that this is a challenging undertaking.

We have demonstrated hyperspectral tip-enhanced Raman imaging on dielectric substrates using linearly polarized light and nanofabricated coaxial antenna tips. A full Raman spectrum was acquired at each pixel of a 256 by 256 pixel contact-mode atomic force microscope image of carbon nanotubes grown on a fused silica microscope coverslip, allowing D and G mode intensity and D-mode peak shifts to be measured with ∼20 nm spatial resolution. Tip enhancement was sufficient to acquire useful Raman spectra in 50-100 ms. Coaxial scan probes combine the efficiency and enhanced, ultralocalized optical fields of plasmonically coupled antennae with the superior topographical imaging properties of sharp metal tips. The yield of the coaxial tip fabrication process is close to 100%, and the tips are sufficiently durable to support hours of contact-mode force microscope imaging. Our coaxial probes avoid the limitations associated with the "gap-mode" imaging geometry used in most tip-enhanced Raman studies to date, where a sharp metal tip is held ∼1 nm above a metallic substrate with the sample located in the gap.