Catálogo de publicaciones - revistas

<jats:title>Revising grain growth</jats:title> <jats:p> Polycrystalline materials will often coarsen during annealing, a process that can modify the physical properties. A generally accepted theory ties the grain boundary curvature to the velocity at which grain boundaries migrate. Bhattacharya <jats:italic>et al</jats:italic> . measured this relationship for 52,000 grains in a nickel sample. They did not observe any relationship between curvature and velocity, suggesting that this accepted theory is not robust for polycrystalline samples. The observations require grain-coarsening models to be updated to more accurately predict the effects of annealing. —BG </jats:p>

<jats:title>Longer and stronger; stiff but not brittle</jats:title> <jats:p> Hydrogels are highly water-swollen, cross-linked polymers. Although they can be highly deformed, they tend to be weak, and methods to strengthen or toughen them tend to reduce stretchability. Two papers now report strategies to create tough but deformable hydrogels (see the Perspective by Bosnjak and Silberstein). Wang <jats:italic>et al</jats:italic> . introduced a toughening mechanism by storing releasable extra chain length in the stiff part of a double-network hydrogel. A high applied force triggered the opening of cycling strands that were only activated at high chain extension. Kim <jats:italic>et al</jats:italic> . synthesized acrylamide gels in which dense entanglements could be achieved by using unusually low amounts of water, cross-linker, and initiator during the synthesis. This approach improves the mechanical strength in solid form while also improving the wear resistance once swollen as a hydrogel. —MSL </jats:p>

<jats:title>Paving the way for KRAS inhibitors</jats:title> <jats:p> KRAS is a key oncogene in multiple cancer types, but existing inhibitors target only a mutant form of KRAS containing the G12C mutation, and their function presents a mechanistic conundrum. It is known that KRAS <jats:sup>G12C</jats:sup> inhibitors bind to the oncoprotein in its inactive form; however, KRAS mutations such as G12C interfere with the action of proteins that normally help it hydrolyze GTP to achieve the inactive state. Li <jats:italic>et al</jats:italic> . have now identified a protein that enhances GTP hydrolysis by mutant KRAS, helping to explain the clinical activity of current drugs targeting this oncoprotein (see the Perspective by Cox and Der). —YN </jats:p>

<jats:title>How to optimize deep-brain stimulation</jats:title> <jats:p> Deep-brain stimulation as presently used in clinical settings, for example, to treat Parkinson’s disease, does not differentiate between different neural circuitries. Considerable improvements could thus be achieved with selective stimulation that targets particular neuronal populations. Spix <jats:italic>et al</jats:italic> . used optogenetics to develop a clever electrical stimulation protocol that enhances cell-type specificity (see the Perspective by Haas). The authors managed to drive population-specific neuromodulation in a brain region called the external globus pallidus with brief bursts of electrical stimulation, which then yielded a long-lasting effect in a mouse model of Parkinson’s disease. —PRS </jats:p>

<jats:title>Mussel mooring made mighty by metals</jats:title> <jats:p> Mussels produce an exceptional proteinaceous adhesive so they can withstand waves and currents. Metal ions bound to modified tyrosine residues play an important role in reinforcing the adhesive. Priemel <jats:italic>et al</jats:italic> . brought together a variety of spectroscopy and microscopy techniques to study the cellular mechanisms involved in adhesive fabrication in mussels (see the Perspective by Wilker). They found that metal ion–rich vesicles are secreted alongside vesicles containing the adhesive protein and mix in a microfluidic-like process within interconnected microchannels found in the lateral duct of the mussel foot to create porous, adhesive plaque filaments. —MAF </jats:p>

<jats:title>Longer and stronger; stiff but not brittle</jats:title> <jats:p> Hydrogels are highly water-swollen, cross-linked polymers. Although they can be highly deformed, they tend to be weak, and methods to strengthen or toughen them tend to reduce stretchability. Two papers now report strategies to create tough but deformable hydrogels (see the Perspective by Bosnjak and Silberstein). Wang <jats:italic>et al</jats:italic> . introduced a toughening mechanism by storing releasable extra chain length in the stiff part of a double-network hydrogel. A high applied force triggered the opening of cycling strands that were only activated at high chain extension. Kim <jats:italic>et al</jats:italic> . synthesized acrylamide gels in which dense entanglements could be achieved by using unusually low amounts of water, cross-linker, and initiator during the synthesis. This approach improves the mechanical strength in solid form while also improving the wear resistance once swollen as a hydrogel. —MSL </jats:p>

<jats:title>Microbes hijack prostate cancer therapy</jats:title> <jats:p> Androgens such as testosterone and dihydrotestosterone are essential for male reproduction and sexual function. Androgens can also influence the growth of prostate tumor cells, and androgen deprivation therapy (ADT) either by surgical means (castration) or pharmacological approaches (hormone suppression), is the cornerstone of current prostate cancer treatments. Pernigoni <jats:italic>et al</jats:italic> . found that when the body was deprived of androgens during ADT, the gut microbiome could produce androgens from androgen precursors (see the Perspective by McCulloch and Trinchieri). Gut commensal microbiota in ADT-treated patients or castrated mice produced androgens that were absorbed into the systemic circulation. These microbe-derived androgens appeared to favor the growth of prostate cancer and helped to facilitate development into a castration- or endocrine therapy–resistant state. —PNK </jats:p>

<jats:title>Coupling light and heat</jats:title> <jats:p> Understanding of the topological features of bandgaps has provided a route for engineering optical structures that exhibit directional propagation of light and are robust to defects. Guddala <jats:italic>et al</jats:italic> . combined a silicon-based topological photonic crystal with an atomic monolayer of hexagonal boron nitride (hBN). The topological features of the photonic crystal are coupled to the lattice vibrations of the hBN through the formation of phonon-polaritons. Funneling of helical infrared phonons along arbitrary pathways and across sharp bends provides the possibility of realizing directional heat dissipation along topologically resilient heat sinks. —ISO </jats:p>

<jats:p> Maricic <jats:italic>et al</jats:italic> . performed an undisclosed in silico–only whole-exome sequencing analysis of our data and found genomic alterations previously undetected in some clones. Some of the predicted alterations, if true, could change the original genotype of the clones. We failed to experimentally validate all but one of these genomic alterations, which did not affect our previous results or data interpretation. </jats:p>