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Anisotropic magnetoresistance (AMR) is the difference in the resistivity of ferromagnetic materials in external magnetic field when the field is applied along or perpendicular to the current. In macroscopic materials the conductance is diffusive (the mean free path of the electron is much smaller than the device dimensions) and AMR is due to spin dependent scattering of impurities. Until recently AMR used to be the primary way of detecting magnetic fields (as in hard-drive read heads).

Here, we control the valence of DNA-functionalized emulsion droplets to make flexible colloidal polymers. We examine their conformational statistics to show that they are freely jointed. We demonstrate that their end-to-end length scales with the number of bonds in agreement with 2D Flory theory, and that their diffusion follows the Zimm model.

Take a trip down the microworld as roboticists Paul McEuen and Marc Miskin explain how they design and mass-produce microrobots the size of a single cell, powered by atomically thin legs -- and show how these machines could one day be "piloted" to battle crop diseases or study your brain at the level of individual neurons.

We investigated the electronic properties of interfaces between two laminated polymer films. The top polymer film (Fig. (a)) is transferred to a soft PDMS stamp, and laminated against the bottom film, previously spin-coated on a substrate. Using electron spectroscopy and Kelvin micro-probe techniques, we demonstrated that the process does not introduce any molecular shift due to interface dipole or surface states. We also showed that the interface is transparent to charge carrier transport, as shown in Fig. (b).

Researchers John Crocker and Andrew Liu at the University of Pennsylvania have discovered that biopolymer networks pruned by tension-inhibited methods remain rigid at much lower coordinations than those pruned randomly. This finding helps explain the evolutionary advantage of tension-inhibited filament-severing proteins in biological systems.

Disordered particulate solids are ubiquitous in items ranging from plastic to concrete. Despite their prevalence, applications can be limited because they are often brittle. In contrast, ductile materials can be deformed smoothly and significantly without fracturing. Strategies for tuning ductility of disordered solids are empirical and system-specific.  Liu, Riggleman and Durian used computer simulations of atomic and polymeric glasses and laboratory experiments on granular packings to develop a general Structuro-Elasto-Plastic (StEP) framework for understanding large-scale deformation of disordered solids in terms of the system-specific interplay between local structure, local rearrangements and larger-scale elasticity.  

The coupling of phonons to electrons, excitons and other phonons plays a defining role in material properties, including charge and energy transport, light emission, and superconductivity. In atomic solids such as Si or GaAs, phonons are delocalized over the three-dimensional (3D) lattice and are determined by bonding and crystal symmetry. In molecular materials, by contrast, localized molecular vibrations couple to electrons to produce, for example, high temperature superconductivity, as in A3C60.

The long-standing goal of increasing material toughness and decreasing brittle failure is elusive in part due to lack of model experimental systems in which ductility can be tuned while observing both macro- and micro-scale response of the constituent “atoms”.  We have now created such a system, as illustrated, wher

A recent study explored the design of coiled coils made up of amino acids, finding that a minimum of three heptads (21 amino acids) is essential for stable formation. A specific 22-residue sequence, BNDL22, showed promising stability and melting temperature for creating nanostructured materials. Incorporating BNDL22 in hydrogels allowed for innovative properties like thermoresponsiveness, making it useful for 3D printing and injections. This research lays the groundwork for developing advanced materials and molecular machines.