A Spintronic Semiconductor with Selectable Charge Carriers Researchers found a semiconductor with two properties crucial for spintronics: a large Rashba effect (splitting of degenerate spin states) and ambipolarity (conduction via electrons and holes). Furthermore, it is possible to control whether the charge carriers are electrons or holes by engineering the surface layer. Read more… Contact: LucaRead More Read more »
Self-Assembly of “S-Bilayers”, a Step Toward Expanding the Dimensionality of S-Layer Assemblies
Protein-based assemblies with ordered nanometer-scale features in three dimensions are of interest as functional nanomaterials but are difficult to generate. Here we report that a truncated S-layer protein assembles into stable bilayers, which we characterized using cryogenic-electron microscopy, tomography, and X-ray spectroscopy. Read more »
Ring Leader: Elke Arenholz, Senior Scientist, Scientific Support Group
Senior scientist Elke Arenholz has seen a lot of changes at Beamlines 4.0.2 and 6.3.1 since she arrived at the ALS in 2000, but what brought her here initially is still what keeps her passionate about her work–designing new instrumentation and working with the user community to optimize research capabilities. Read more »
Snapshots of Ribozyme Reaction States Reveal Structural Switch
RNA, like protein, can sometimes function as an enzyme (ribozyme) to speed biochemical reaction rates. But how does RNA, a simple polymer, enhance reaction rates by at least a million fold? Researchers obtained the structures of a ribozyme trapped in different states of its catalytic cycle, showing how a change in the RNA conformation governs the reaction mechanism. Read more »
Designing a Novel Globular Protein Fold
A major challenge of computational structural biology has been to create, from scratch, new proteins with heretofore unobserved three-dimensional structures. Researchers have now developed and demonstrated a methodology for protein-structure prediction and design by creating the first artificial globular protein with a novel topology. Significantly, the x-ray structure agreed almost precisely with the structure specified by the computational model. Read more »
The Path of Messenger RNA through the Ribosome
Using x-ray crystallography, researchers directly observed the path of mRNA in the 70S ribosome in Fourier difference maps at 7 Å resolution. Image depicts the view down the crystallographic 4-fold axis of the 70S ribosome-mRNA-tRNA complex, showing the head-to-tail juxtaposition of the model mRNAs (red-orange) between adjacent ribosomes. Read more »
Crosslink Density of Superabsorbent Polymers
Researchers from The Dow Chemical Company teamed with academic colleagues to conduct x-ray spectromicroscopy studies of superabsorbent polymers (SAPs), materials with a wide range of applications, including disposable baby diapers. Dow has been able to use the results to help develop the process technology for a new SAP-manufacturing plant. Read more »
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