Pictured is an illustration of several nuclear pore complexes (NPCs) embedded in a cell nucleus. NPCs act as gatekeepers between a cell’s cytoplasm and its nucleus. Based on crystallographic analyses, Sozanne R. Solmaz et al. uncover the molecular mechanism that underlies the large changes in diameter of NPCs and suggest a “ring cycle” mechanism for dilating and constricting the central NPC channel. The model could explain the ability of NPCs to accommodate transport substrates of a large size range and rapidly adjust to cellular transport needs. Read more »
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Jamming Behavior of Domains in a Spiral Antiferromagnetic System
This schematic of x-ray scattering is from a spiral antiferromagnet with a spin structure that gives rise to domains with jamming behavior. Using resonant magnetic x-ray photon correlation spectroscopy, this research shows that the domains of a spiral antiferromagnet enter a jammed state at the onset of long-range order. Researchers found that slow thermal fluctuations of the domain walls exhibit a compressed exponential relaxation with an exponent of 1.5 found in a wide variety of solid-like jammed systems and can be qualitatively explained in terms of stress release in a stressed network. As the temperature decreases, the energy barrier for fluctuations becomes large enough to arrest further domain wall fluctuations, and the domains freeze into a spatial configuration within 10 K of the Néel temperature. The relaxation times can be fitted with the Vogel-Fulcher law as observed in polymers, glasses, and colloids, thereby indicating that the dynamics of domain walls in an ordered antiferromagnet exhibit some of the universal features associated with jamming behavior. 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 »
FDA Approves Drug for Type 2 Diabetes Invented with Aid of Protein Structure Data Taken at ALS
In January 2013, the U.S. Food and Drug Administration approved NESINA for the treatment of type 2 diabetes in adults as an adjunct to diet and exercise. NESINA was invented by scientists at Takeda California, who used ALS Beamlines 5.0.2 and 5.0.3 to collect x-ray diffraction data.
Solar Cells: Spin-Cast Bulk Heterojunction Solar Cells: A Dynamical Investigation
Spin-coating is extensively used in the lab-based manufacturing of organic solar cells, including most of the record-setting cells. Aram Amassian and co-workers report in this study the first direct observation of photoactive layer formation as it occurs during spin-coating. The study provides new insight into mechanisms and kinetics of bulk heterojunction formation, which may be crucial for successful transfer to printing processes and scaling up production. Read more »
Real-Time Quantitative Imaging of Failure Events in Materials Under Load at Temperatures Above 1,600 °C
Gathering information on the evolution of small cracks in ceramic matrix composites used in hostile environments such as in gas turbines and hypersonic flights has been a challenge. It is now shown that sequences of microcrack damage in ceramic composites under load at temperatures up to 1,750 °C can be fully resolved with the use of in situ synchrotron x-ray computed microtomography. Read more »
Moving Memristor and Neuristor Research Forward
HP Labs researchers have tackled a decades-old mystery relying on powerful ALS microscopy techniques—to better understand the fourth basic circuit element: the memristor. The memristor (short for “memory resistor”) joins the other passive elements—the capacitor, the resistor, and the inductor—to create a device with the ability to “remember” changes even when it loses power. Commercial development based on memristors offers the promise of computing systems with highly advanced energy efficiency and memory retention. Memristor-based memory could be a strong competitor for current flash memory.
Chemistry of Cobalt-Platinum Nanocatalysts
Bimetallic cobalt-platinum (CoPt) nanoparticles are drawing attention in many areas of catalysis as scientists tackle the quest to reduce precious metal content while maintaining optimum catalytic selectivity and reactivity. Researchers explored the role of Pt in Co reducing and oxidizing, and found that the catalytic properties of monometallic and bimetallic nanoparticles of Co are closely related to the oxidation state of Co. Read more »
Crystallographic Consulting Brings Research to the ALS
Crystallographic Consulting has a varied client base that includes many of the participating research team (PRT) members at the Berkeley Center for Structural Biology (BCSB), which operates five ALS beamlines. Crystallographic Consulting also contracts beam time for another 10-12 companies. Most of their research supports pharmaceutical companies working on new treatments for metabolic diseases and cancer.
Chloride Depletion in Aged Sea Salt Particles
Elemental and chemical imaging analyses showed that sea salt particles react with water-soluble organic acids in the atmosphere through a unique mechanism which had been overlooked in atmospheric chemistry. The reactions release volatile hydrogen chloride into the atmosphere and leave behind sea salt particles drained of chloride.
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